skim

things you should know about javascript

2012-02-06T07:00:00-08:00

Note: this post originally appeared on 8th Light's website.

I know some people cringe at the idea of writing JavaScript. They opt to write CoffeeScript instead and make every attempt to avoid looking at those funny looking mustaches.

It is however, advantageous to learn JavaScript and learn the advanced features, even the odd things about the language. Here’s a collection of things you should know:

Short-hand syntax for creating Arrays and Objects

Prefer to use [] for arrays and {} for objects instead of new Array() and new Object().

Other than being syntactically shorter, particularly new Array() yields different results depending on the arguments you provide.

Passing a single Number argument will change the length of the array after instantiation.
```
      var array = new Array(2);
      array.length;  // 2
      
```
I’m not sure why you would do this because arrays in JavaScript are dynamic. Passing in a single argument that is not a Number or passing more than one argument will instantiate the array with the arguments provided.
```
      var array1 = new Array(true);
      array1;  // [true]

      var array2 = new Array(1, "a", {});
      array2;  // [1, "a", {}]
      
```
Objects are easier to build when using the short-hand syntax.
```
      var object1 = { key1 : 'value1', key2 : 'value2' };

      var object2 = new Object();
      var object.key1 = 'value1';
      var object.key2 = 'value2';
      
```
dot notation vs. subscript notation (bracket notation)

You can call properties/methods using dot notation or subscript notation.
```
      var object = {
        value : 42,
        fn : function() {
          return "hello world";
        }
      }

      object.value;  // 42
      object["value"];  // 42
      object.fn();  // "hello world"
      object["fn"]()  // "hello world"
      
```
You might ask why you'd ever want to use subscript notation. Subscript notation allows for dynamic creation of properties and methods. So if you ever do any sort of metaprogramming, you'll most likely be using the subscript notation.
=== and !===

CoffeeScript has this right. Prefer === and !== over == and !=. The reason for this is due to type coercion when using the equality operator.
```
      "0" == 0;  // true
      "0" == false;  // true
      undefined == null;  // true
      " \t\r\n" == 0;  // true
      
```
JavaScript considers 0 and "" to be falsy unlike Ruby. If the strict equality operator (===) was used in the above examples, they would all return false.
Function Scope, The Only Scope
```
      if (true) {
        var SomeObject = {};
      }
      
```
What is the value of SomeObject outside of the if statement? Is it undefined? Or {}?

Believe it or not, code wrapped in m̶u̶s̶t̶a̶c̶h̶e̶s̶ curly braces does not have scope. Only functions create scope. Therefore, SomeObject is {}.
```
      function a() {
        var b = 1;
      }

      a();
      b;  // ReferenceError
      
```

Hoisting

      if (!SomeObject) {
        var SomeObject = {};
      }

For this example, what is the value of SomeObject? Is it undefined? Or {}? Or some Error? This is probably one of the most interesting parts of JavaScript. Right before the code is executed, all variable declarations are hoisted to the top of the given scope. The example above turns into this before execution:

      var SomeObject;

      if (!SomeObject) {
        SomeObject = {};
      }

So, the value of SomeObject is {}. Similarly, function declarations are hoisted to the top as well. This example:

      abracadabra();
      function abracadabra() {
        var magic = "it works!";
      }

works because it looks like this before execution:

      function abracadabra() {
        var magic = "it works!";
      }
      abracadabra();

It's magic!

Casting Values

There are several ways to cast a primitive value. The simplest way is to use the String, Number, Boolean functions:

      String(42);  // "42"
      Number("42");  // 42
      Boolean("true");  // true

Cool kids like to use this approach, which works the same way:

      // cast string to number using the plus operator
      +"42";  // 42

      // cast number to string using an empty string and coercion
      "" + 42;  // "42"

Using Number methods on Number literals

Ever wondered why you can call String methods on String literals, but not Numbers?
```
      "1 2 3".split(" ");  // ["1", "2", "3"]

      2.toFixed();  // SyntaxError
      
```
According to the JavaScript Garden documentation, it's because a flaw in JavaScript's parser tries to parse the dot notation on a number as a floating point literal. The best way to handle this issue is to wrap the Number literal in parentheses.
```
      (2).toFixed();  // "2"
      
```
arguments object is not an Array

The arguments object has a length property, but it is not an Array. Therefore, you cannot directly call Array methods from the arguments object. The best way to do this is to use call or apply.
```
      Array.prototype.shift.call(arguments);
      
```

Privatizing variables

With closure, you can create privatized variables in JavaScript.

      var fn = (function() {
        var privatizedVariable = "private";
        return function() {
          return privatizedVariable;
        };
      })();

      fn();  // "private"
      privatizedVariable;  // ReferenceError

There are a ton more advanced features that everyone should know that are outside the scope of this post (or my lack of explaining it better than the books/articles out there):

Prototypal inheritance
call and apply
function expressions vs. function declarations vs. named function expressions
Name Resolution Order

You can read more about them below.

Master your JavaScript-Fu. Enjoy.

Reference

JavaScript Garden
JavaScript Patterns
JavaScript Scoping and Hoisting
Dmitry's JavaScript Quiz
Kangax's JavaScript Quiz
Named Function Expressions Demystified
Douglas Crockford's JavaScript: The Good Parts
Why of WAT

rsa public key interoperability between ruby and android

2012-01-16T05:00:00-08:00

I recently worked on a project where sensitive information needed to be sent from an Android app to a Ruby-based server. Our solution was to use asymmetric encryption (the actual implementation was more involved, but for the sake of simplicity, let’s just focus on asymmetric encryption, namely RSA). Using an RSA key pair generated by the Ruby-based server, the Android app encrypted sensitive information using the RSA public key and the server decrypted the sensitive data using the RSA private key. This sounds straightforward, but what I’m going to talk about here is an issue when using an RSA public key generated from pre-Ruby 1.9.3 in an Android app and several solutions to work around the issue.

TL;DR

Solutions to this problem:

On the server side, encode pre-Ruby 1.9.3 RSA public keys using the X.509 format – gist (thanks Martin!).
Android Standard Library comes with a crippled version of BouncyCastle. Grab the full version of BouncyCastle and grab the classes necessary to extract the exponent and modulus of the PKCS#1 encoded public key to create a PublicKey object – gist.

RSA Public Key Encoded Format Problem in pre-Ruby 1.9.3

The Ruby-based server generates the RSA key pair and stores the RSA private key in its database. If you know RSA, you know if you have the private key, you can easily generate its public key counterpart, but not vice versa. Using the public key given by the server, I attempted to load it in the Android app.

In Ruby, you can simply load up a public key by passing it to OpenSSL::PKey::RSA::new.

require 'openssl'
require 'base64'

public_key = "MIIBCgKCAQEA20O377QEiZvPsj14LKl2xO23iirJB5WDTVjeab1cIOJu1vbV+Pdwl1Bov8m896ZG4K0S/qvfJcdHLovr2WJ+o2maK1XZCNy8lA" +
  "zIPzZrj/yDZAB2GSjR3in1lQRQPtWjIOdB8Cy2FGybEstIkpf8MD3XMWp5g8BtdOv43ekjBuTiGGLlPRG0+IiazjHlWjyl6DU9x9m2Jxks0H6YZud6zf4s9Q6" +
  "9vPUYgOZXWs7IghxqrVGE5mWxoRudsDFhLYP706+IrSxGOf5fE0/8fjtzj/eJayCLmkUWq/xsts5tBAbwsX5xKdk8iD0OU2qOEbVuiYmehEiJnvO2vyd+t76C" +
  "xwIDAQAB"

rsa_public_key = OpenSSL::PKey::RSA.new(Base64.decode64(public_key))

Unfortunately, in Android, it’s a bit more complex (oh, Java!). You have to first get an instance of KeyFactory, create an X509EncodedKeySpec, pass in the public key string, then generate the public key using that key spec.

public PublicKey getPublicKey() {
    try {
        String publicKey = "MIIBCgKCAQEA20O377QEiZvPsj14LKl2xO23iirJB5WDTVjeab1cIOJu1vbV+Pdwl1Bov8m896ZG4K0S/qvfJcdHLovr2WJ+" +
            "o2maK1XZCNy8lAzIPzZrj/yDZAB2GSjR3in1lQRQPtWjIOdB8Cy2FGybEstIkpf8MD3XMWp5g8BtdOv43ekjBuTiGGLlPRG0+IiazjHlWjyl6DU" +
            "9x9m2Jxks0H6YZud6zf4s9Q69vPUYgOZXWs7IghxqrVGE5mWxoRudsDFhLYP706+IrSxGOf5fE0/8fjtzj/eJayCLmkUWq/xsts5tBAbwsX5xKd" +
            "k8iD0OU2qOEbVuiYmehEiJnvO2vyd+t76CxwIDAQAB";
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        X509EncodedKeySpec encodedPubKeySpec = new X509EncodedKeySpec(Base64.decode(publicKey, Base64.NO_WRAP));
        return keyFactory.generatePublic(encodedPubKeySpec);
    } catch (NoSuchAlgorithmException e) {
      e.printStackTrace();
    } catch (InvalidKeySpecException e) {
      e.printStackTrace();
    }
    return null;
}

Unfortunately, this raises an InvalidKeySpecException. Countless Google queries resulting in many hours of yak shaving, led me to dead ends. It was when I kicked off a Ruby 1.9.3 irb instance that showed me the light.

RSA Encoded Format in Ruby 1.9.3

In a Ruby 1.9.3 irb instance, I loaded the same public key I generated from Ruby 1.8.7 and to my surprise, noticed the public key changed in the front of my eyes.

require 'openssl'
require 'base64'

public_key = "MIIBCgKCAQEA20O377QEiZvPsj14LKl2xO23iirJB5WDTVjeab1cIOJu1vbV+Pdwl1Bov8m896ZG4K0S/qvfJcdHLovr2WJ+o2maK1XZCNy8lA" +
  "zIPzZrj/yDZAB2GSjR3in1lQRQPtWjIOdB8Cy2FGybEstIkpf8MD3XMWp5g8BtdOv43ekjBuTiGGLlPRG0+IiazjHlWjyl6DU9x9m2Jxks0H6YZud6zf4s9Q6" +
  "9vPUYgOZXWs7IghxqrVGE5mWxoRudsDFhLYP706+IrSxGOf5fE0/8fjtzj/eJayCLmkUWq/xsts5tBAbwsX5xKdk8iD0OU2qOEbVuiYmehEiJnvO2vyd+t76C" +
  "xwIDAQAB"

rsa_public_key = OpenSSL::PKey::RSA.new(Base64.decode64(public_key))

# strip newlines and begin/end markers
new_public_key = rsa_public_key.to_s.gsub("\n", "").gsub(/-----(BEGIN|END) PUBLIC KEY-----/, "")
# => "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA20O377QEiZvPsj14LKl2xO23iirJB5WDTVjeab1cIOJu1vbV+Pdwl1Bov8m896ZG4K0S/qvfJcdHLovr2WJ+o2maK1XZCNy8lAzIPzZrj/yDZAB2GSjR3in1lQRQPtWjIOdB8Cy2FGybEstIkpf8MD3XMWp5g8BtdOv43ekjBuTiGGLlPRG0+IiazjHlWjyl6DU9x9m2Jxks0H6YZud6zf4s9Q69vPUYgOZXWs7IghxqrVGE5mWxoRudsDFhLYP706+IrSxGOf5fE0/8fjtzj/eJayCLmkUWq/xsts5tBAbwsX5xKdk8iD0OU2qOEbVuiYmehEiJnvO2vyd+t76CxwIDAQAB"

new_public_key == public_key
# => false

I tried to see if Ruby 1.9.2 produced the same results; the public key was the same as 1.8.7. I then tried generating a new public key in Ruby 1.9.3, then initialize that key in another OpenSSL::PKey::RSA instance in 1.9.3, but the key was identical. This led me to believe that something changed in Ruby 1.9.3 that is not in Ruby 1.8.7/Ruby 1.9.2. I searched on Google again for clues and fortunately found something relevant. Martin Boßlet’s filed a bug report for Ruby 1.9.3; in the report, he describes how the encoded format for RSA public keys was not the default format used by OpenSSL, but rather the encoding format specified by PKCS#1. The fix shows Martin changing PEM_read_bio_RSAPublicKey to PEM_read_bio_RSA_PUBKEY. Perusing in the OpenSSL documentation shows what Martin was describing in the bug report: RSAPublicKey encodes the public key using the PKCS#1 RSAPublicKey structure rather than the SubjectPublicKeyInfo structure. The former structure is not compatible with the crypto library available in Android.

The fix has been applied to Ruby-1.9.3-p0, but the problem is still present for all Ruby versions prior. This means the Ruby-based server is still affected and the path to upgrading to 1.9.3 for us was not an option. I needed to approach the problem differently and reached out to Martin for some assistance. He was extremely helpful and came up with this solution.

Solution #1: Encode pre-Ruby 1.9.3 RSA public keys using the X.509 format (gist)

require 'openssl'
require 'base64'

rsa = OpenSSL::PKey::RSA.new(2048)
modulus = rsa.n
exponent = rsa.e

oid = OpenSSL::ASN1::ObjectId.new("rsaEncryption")
alg_id = OpenSSL::ASN1::Sequence.new([oid, OpenSSL::ASN1::Null.new(nil)])
ary = [OpenSSL::ASN1::Integer.new(modulus), OpenSSL::ASN1::Integer.new(exponent)]
pub_key = OpenSSL::ASN1::Sequence.new(ary)
enc_pk = OpenSSL::ASN1::BitString.new(pub_key.to_der)
subject_pk_info = OpenSSL::ASN1::Sequence.new([alg_id, enc_pk])

base64 = Base64.encode64(subject_pk_info.to_der)

#This is the equivalent to the X.509 encoding used in >= 1.9.3
pem = "-----BEGIN PUBLIC KEY-----\n#{base64}-----END PUBLIC KEY-----"

Martin basically wrote the X.509 encoding format from scratch. This would have worked for us, but unfortunately, we have already issued RSA public keys to customers and needed to support the PKCS#1 encoded format public keys.

I googled some more and found a solution that extracts the exponent and modulus from the public key. With the exponent and modulus, I can create a PublicKey object.

Solution #2: Full Version of BouncyCastle and RSAPublicKeyStructure (gist)

This solution requires classes that are not available in the Android Standard Library. A Google result provides details about the problem with the Android Standard Library’s crippled version of BouncyCastle. To remedy this problem, grab the full version of BouncyCastle and bring in only the required classes to extract the exponent and modulus of the public key string.

After adding BouncyCastle classes, I created a static method that reads pre-Ruby 1.9.3 public keys, extracts the exponent and modulus, and returns a PublicKey object:

import java.io.IOException;
import java.security.KeyFactory;
import java.security.NoSuchAlgorithmException;
import java.security.PublicKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.RSAPublicKeySpec;

import org.bouncycastle.asn1.ASN1InputStream;
import org.bouncycastle.asn1.DERObject;
import org.bouncycastle.asn1.x509.RSAPublicKeyStructure;
import org.bouncycastle.util.encoders.Base64;

public class RSAUtil {
    static public PublicKey publicKey(String publicKeyString) {
        try {
            byte[] decodedPublicKey = Base64.decode(publicKeyString);
            ASN1InputStream in = new ASN1InputStream(decodedPublicKey);
            DERObject obj = in.readObject();
            RSAPublicKeyStructure keyStruct = RSAPublicKeyStructure.getInstance(obj);
            RSAPublicKeySpec keySpec = new RSAPublicKeySpec(keyStruct.getModulus(), keyStruct.getPublicExponent());
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            return keyFactory.generatePublic(keySpec);
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (InvalidKeySpecException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }
}

Conclusion

This is definitely a unique cryptography issue between Ruby and Android. As far as I know, the Ruby team has no plans to backport the Ruby 1.9.3 fix into prior Ruby versions, but the solutions I have presented should be sufficient for your needs to make public keys interoperable between Ruby and Android. Feel free to comment if you have any questions or different solutions to this problem.

mac os x lion development environment

2011-11-13T12:00:00-08:00

I finally bit the bullet and installed Lion on my Macbook Pro. Mac OS X Lion released almost four months ago and comes with some interesting features. You can read about them in detail here. What I’m going to write about here are some of the hurdles I had to overcome. Perhaps when it’s time for you to upgrade, you won’t have to experience them. Of course, YMMV.

TL;DR

Time Machine does not work if FileVault is enabled
Use encrypted disk images or TrueCrypt instead of FileVault
Lion Disk Utility detects if hard drive has too many S.M.A.R.T. errors and simply refuses to install Lion if so
Had to replace hard drive (should have purchased SSD, c’est la vie)
XCode 4.2 is not rvm/homebrew friendly. Have to use XCode 4.1
XCode 4.1 installer installs Install XCode.app in your Applications folder. You then have to install Install XCode.app to install XCode. Not confusing at all.
Homebrew does not have a vim formula (not talking about macvim). Have to compile on your own.

Getting Ready

I could have easily upgraded to Lion from Snow Leopard, but I wanted a clean slate. I collected a lot of cruft over the year and a half and I thought it would be educationally rewarding to set up the development environment again, but this time without a guide. I also wanted a clean dot-file slate, learn about the commands in each dot-file instead of just accepting them and taking them for granted.

If you already have Time Machine set up (or similar backup software), then you’re already ahead of the game. I did not have any backup software installed/enabled (hard drives can fail???), so I manually copied directories and files over to my home NAS. I didn’t have a lot of stuff that I cared to back up, so this was a rather easy process.

Lion on USB

Since I planned to wipe out the hard drive and start fresh, I needed to store the Lion installer on a USB thumb drive. Apple offers a USB thumb drive option, but why pay $69 when you can do it for free? There are many guides out there with detailed instructions on how to extract the core file from Lion installer and transfer it to your USB thumb drive.

Let’s Install

I rebooted the computer, inserted the thumb drive, and held down the Option key. I proceeded to the Disk Utility and wiped out my hard drive. Then when I attempted to install Mac OS X Lion, I was greeted with S.M.A.R.T. errors message. If you can’t select the hard drive to tell the Lion installer the destination of your install, then chances are, you have S.M.A.R.T. errors. I googled this issue and lots of people have reported the same issue. The hard drive worked fine in Snow Leopard, Lion does not want to do anything with it.

I ordered a new hard drive from Amazon.com, waited a day for it to arrive, then tried again. No S.M.A.R.T. errors. BOOM, it let me proceed and within 15 minutes, Lion was on my machine.

Post Install

First thing I did was check for Software Updates because I was well aware of the updates that had come in post Lion release date. After that, I proceeded to install software I care about (in alphabetical order):

Briquette (Propane alternative for Campfire)
Chrome
iTerm
Silverlight (Netflix)
SizeUp (window sizing tool)
Skype
VLC
VMWare Fusion
Vox

Development Environment

The following tools were installed to aid my development needs:

rvm (yes, I know about rbenv)
homebrew
XCode 4.1 (4.2 is evil)
git
vim (not macvim)
Tomorrow Theme for vim
vimfiles
ctags (for vim)
zsh
zsh-syntax-highlighting (fish shell-like support for zsh)
tmux

I know some hate rvm and prefer rbenv, but I’m fine with it. I installed homebrew next. Homebrew requires XCode, and I knew that beforehand; what I didn’t know about is that it doesn’t like XCode 4.2. The App Store only has version 4.2 (and higher when you read this post at a later date). The homebrew notes has the link to version 4.1. Download and install. Here’s a caveat: the dmg contains an installer. The installer installs Install XCode.app in your Applications folder. You’ll need to run that installer to finally get XCode installed. This confused me to no end for an hour.

Git, ctags, zsh, and tmux installations were straight forward. Homebrew is your friend. Unfortunately though, homebrew does not have a vim formula (and probably does not plan to). ~~I had to install this from scratch. This is probably the long-winded process of getting it installed, but I digress:~~ Update: You can brew install it.

brew install https://raw.github.com/adamv/homebrew-alt/master/duplicates/vim.rb

I have been using MacVim for the past year and a half, but since this summer have been using it exclusively. I’m taking a step further and switch to vim, so I can use it in tmux sessions, over ssh, etc. I used to use AkitaOnRails’ vimfiles, but decided to adopt this vimfiles instead. I’m using this setup right now to write this blog post and so far I’m loving it.

Caveats to getting the vimfiles to work. If you’re a fan of wincent’s Command-T, then this may be troublesome. The plugin kept segfaulting, so I removed it completely from the bundle directory. This is even after compiling Command-T using system ruby. The vimfiles uses FuzzyFinder anyway, so it’s not the end of the world.

The vim that came with Lion will not work with vim plugins that need Ruby support. You can easily check this by checking the version (vim --version). It should have a plus next to ruby. So if FuzzyFinder is not working for you, it’s because ruby was not enabled for the vim you have.

Final Words

Hope you enjoyed the TL;DR post. I know I wasn’t very descriptive on every step of the process, so if you have any questions, let me know in the comments.

gnu smalltalk koans

2011-06-21T21:59:00-07:00

It’s been a while since I blogged here, but I recently gave a talk, “Introduction to GNU Smalltalk” at Chicago Code Camp and just moments ago, “GNU Smalltalk Koans” at the Software Craftsmanship McHenry meetup. Yes, you read that right. A set of tests to teach you the Smalltalk language. See slides here.

Heavily inspired by Ruby Koans and Clojure Koans, GNU Smalltalk Koans attempts to teach you the Smalltalk language, syntax, and most of the standard libraries. If you’re a Rubyist and have not been exposed to Smalltalk, here’s your chance to find out how much Smalltalk influenced Ruby.

The README.markdown should suffice in getting you started, but let’s get down to the nitty gritty and reach our way to enlightenment.

Requirements

Mac OS X or Linux
GNU Smalltalk 3.2.2 or higher
an editor of your choice that supports Smalltalk (e.g., redcar, vim, emacs, Textmate)

Note: Unfortunately, Windows support is not available at this time. I’m unable to build it on my system, but feel free to fork the project and contribute!

Git Clone Project or Download tarball/zip

If you have git on your system, the easiest way to get the koans is to perform:

git clone git@github.com:sl4m/gnu_smalltalk_koans.git

If you don’t have git, not a problem. Go to the Downloads section to grab your tarball or zip file and extract it to a location of your choosing.

Running Koans

Once you’re ready to dive in, simply type: script/run in the project root directory. You will see a message like:

TestAssert#testTruth has damaged your karma.

It will tell you which file to open and which test to correct. In this case, you’ll need to open TestAssert.st file under src/koans and correct testTruth method (aka message). Once you have corrected the test, re-run script/run to see what other koans might have damaged your karma. Repeat and rinse.

Closing

Be sure to read the rest of the README.markdown as it has some important information. This is an open source project, so feel free to fork it, contribute, give feedback, I’m all ears! Thanks for stopping by!

jasmine on rails

2011-02-19T10:45:00-08:00

My first 8LU (8th Light University) series was on Jasmine. I learned Jasmine on a recent Rails 3 project and found it be a nice addition to the testing arsenal. There are still some quirks with the framework, but the Pivotal guys are behind it and it can be used now in any project. I look forward to using it more in future projects.

The slides are online here. The slides repo is here.

tic tac toe in smalltalk

2010-12-03T17:30:00-08:00

During my apprenticeship, I wrote a Tic Tac Toe program in Smalltalk. Initially, I planned on using Pharo, one of the major Smalltalk implementations, but found out about GNU Smalltalk and its POSIX compatibility, and went with that instead. Unfortunately (or fortunately?), GNU Smalltalk does not give you the full experience of Smalltalk. Smalltalk is about the living environment experience, not so much about the language and its semantics. As you start reading the source code, you’ll start to notice some similarities between Smalltalk and Ruby. This is because Smalltalk was a major influence to Ruby. This is one of the main reasons why I chose to write Tic Tac Toe in Smalltalk.

Anyway, before I go off on talking about Smalltalk history, the source code is on my GitHub repo. Here is a sample of what the code looks like:

Board subclass: ThreeByThree [
  ThreeByThree class >> new [
    ^super new initialize
  ]

  ThreeByThree class >> create: existingBoard [
    ^self new
          list: existingBoard;
          yourself
  ]

  initialize [
    super initialize.
    winningPatterns := #((1 2 3) (4 5 6) (7 8 9) (1 4 7) (2 5 8) (3 6 9) (1 5 9) (3 5 7)).
    list := Array new: 9 withAll: ' '.
  ]

  findPattern: pattern [
    ((list at: (pattern at: 1)) = 'X' & (list at: (pattern at: 2)) = 'X' & (list at: (pattern at: 3)) = 'X')
      ifTrue: [winner := 'X'].
    ((list at: (pattern at: 1)) = 'O' & (list at: (pattern at: 2)) = 'O' & (list at: (pattern at: 3)) = 'O')
      ifTrue: [winner := 'O'].
  ]
]

redcar - my new favorite text editor

2010-10-01T16:30:00-07:00

Redcar is a new, platform-independent, Ruby-based text editor that looks and feels like Textmate, but it’s open-source and free. It’s currently in alpha and there are some things that it cannot do at this time, but it’s pretty stable and I use it to quickly bring up projects, something IDEs typically cannot do quickly enough. Mind you, if you have already purchased Textmate, trying out Redcar might be stepping backwards. For users who does not own Textmate or e-texteditor (for Windows), Redcar might be a nice option.

Installation

The installation is pretty straight forward. You just install the redcar gem and run redcar install command. Afterwards, you run redcar. I’m sure there’s a better way to do this, but currently, I have the redcar process running on one Terminal tab and call redcar to open up different projects.

It supports Textmate Themes and Bundles

One great benefit to using Redcar is its ability to take advantage of the Textmate themes and bundles. So it basically can open any file and display proper syntax highlighting and commands. I’m also a big fan of the Sunburst theme and glad to see I do not need to create it for this editor.

It supports Plugins

Another great benefit is its extensibility. It allows the community to create plugins that other users can use. Here’s a nice list of plugins that people have written so far.

GiHub repo and Bug tracking

If you want to contribute, go to the GitHub repo and help out. You can also report bugs here.

Go play with it

Try it out! Especially for Windows users who only have options like e-texteditor or IntelliJ/RubyMine, Redcar is clean, minimal, and does not get in your way.

bowling kata in java

2010-09-23T23:00:00-07:00

Note: It’s better to watch the video on Vimeo’s website since Vimeo does not allow HD embedding for free users.

Here is my attempt to perform Uncle Bob’s Bowling Kata in Java.

I used IntelliJ as my IDE and music by The Sight Below. His live set can be downloaded for free here. If you don’t like the music, feel free to put it on mute.

I encourage you to watch the video while looking at Uncle Bob’s notes in the powerpoint presentation.

sieve of eratosthenes with rspec

2010-09-09T11:00:00-07:00

Update: My Sieve implementation is nowhere near as fast as the one posted here.

Four months ago, I wrote Sieve of Eratosthenes algorithm in Ruby. Today, I wanted to try it again with RSpec tests and a kata-like style. You’ll notice the test is inspired by Uncle Bob’s kata test for Prime Factors.

sieve_spec.rb

$: << File.expand_path(File.dirname(__FILE__))
require 'spec'
require 'sieve'

describe Sieve do
  [
    [1,   []],
    [2,   [2]],
    [3,   [2,3]],
    [4,   [2,3]],
    [5,   [2,3,5]],
    [6,   [2,3,5]],
    [7,   [2,3,5,7]],
    [8,   [2,3,5,7]],
    [9,   [2,3,5,7]],
    [10,  [2,3,5,7]],
    [11,  [2,3,5,7,11]],
    [13,  [2,3,5,7,11,13]],
    [17,  [2,3,5,7,11,13,17]],
    [19,  [2,3,5,7,11,13,17,19]],
    [23,  [2,3,5,7,11,13,17,19,23]],
    [29,  [2,3,5,7,11,13,17,19,23,29]],
    [100, [2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,97]]
  ].each do |number, primes|
    it "returns prime numbers up to #{number}" do
      Sieve.of(number).should == primes
    end
  end
end

sieve.rb

module Sieve
  def self.of(n)
    return [] if n <= 1
    not_primes = []
    (2..n).each do |num|
      if num <= Math.sqrt(n)
        (2..n).each do |p|
          not_primes << p if num != p && p % num == 0
        end
      end
    end
    return (2..n).to_a - not_primes
  end
end

rails 3 rc on windows using rubyinstaller 1.9.2

2010-08-21T10:00:00-07:00

Update: Rails 3 is now available. The instructions below should also work for the final release.

Update 2: MySQL2 gem (starting with version 0.2.5) officially works for Windows. See gist.

This week the Ruby team released the most anticipated Ruby version, 1.9.2, and yesterday, the RubyInstaller team released 1.9.2 for Windows. Kudos to both teams for the hard work and dedication.

Requirements

Installation

Installing Ruby using RubyInstaller should be straight forward. The installer automatically defaults the path to C:\Ruby192. If you have used DevKit in the past, you’ll notice this DevKit requires a different way to install. I highly recommend following the instructions here. You’ll need to remove the old DevKit install for other Ruby installations and install the new DevKit using the dk.rb script.

Install Rails 3 using the –pre parameter. Update: –pre is no longer necessary now that Rails 3 is official

c:\devkit>gem install rails --pre
Temporarily enhancing PATH to include DevKit...
Successfully installed activesupport-3.0.0.rc
Successfully installed builder-2.1.2
Successfully installed i18n-0.4.1
Successfully installed activemodel-3.0.0.rc
Successfully installed rack-1.2.1
Successfully installed rack-test-0.5.4
Successfully installed rack-mount-0.6.11
Successfully installed tzinfo-0.3.23
Successfully installed abstract-1.0.0
Successfully installed erubis-2.6.6
Successfully installed actionpack-3.0.0.rc
Successfully installed arel-0.4.0
Successfully installed activerecord-3.0.0.rc
Successfully installed activeresource-3.0.0.rc
Successfully installed mime-types-1.16
Successfully installed polyglot-0.3.1
Successfully installed treetop-1.4.8
Successfully installed mail-2.2.5
Successfully installed actionmailer-3.0.0.rc
Successfully installed thor-0.14.0
Successfully installed railties-3.0.0.rc
Successfully installed bundler-1.0.0.rc.5
Successfully installed rails-3.0.0.rc
23 gems installed

If you read my previous Rails 3 post, we had to install a lot of the dependencies separately. The latest Rails gem seems to take care of it. Also, RubyInstaller comes with Rake, so you do not need to install it.

Next up is installing SQLite or MySQL (your preference).

Note: The official Rails blog mentions support for the MySQL2 gem which takes care of the MySQL encoding issues on Ruby 1.9.2. At the time of this writing, I could not install MySQL2 gem on my Windows box, but the gem author seems to be fully aware of the situation. In the meantime you should be able to use SQLite or MySQL with the mysql gem.

Let’s install SQLite:

c:\devkit>gem install sqlite3-ruby
Temporarily enhancing PATH to include DevKit...

=============================================================================

  You've installed the binary version of sqlite3-ruby.
  It was built using SQLite3 version 3.6.23.1.
  It's recommended to use the exact same version to avoid potential issues.

  At the time of building this gem, the necessary DLL files where available
  in the following download:

  http://www.sqlite.org/sqlitedll-3_6_23_1.zip

  You can put the sqlite3.dll available in this package in your Ruby bin
  directory, for example C:\Ruby\bin

=============================================================================

Successfully installed sqlite3-ruby-1.3.1-x86-mingw32
1 gem installed

The instructions above says to use SQLite version 3.6.23.1 and provides a link to the dll. I would also get the exe which is available here. Place sqlite3.dll and sqlite3.exe in C:\Ruby192\bin or a general bin directory in the PATH (thanks for the correction, Luis!).

Now let’s create a new Rails app. Note, the new command to create the app:

E:\p\rails>rails new rails3rc --database=sqlite3
      create
      create  README
      create  Rakefile
      create  config.ru
      create  .gitignore
      create  Gemfile
      create  app
      create  app/controllers/application_controller.rb
      create  app/helpers/application_helper.rb
      create  app/views/layouts/application.html.erb
      create  app/mailers
      create  app/models
      create  config
      create  config/routes.rb
      create  config/application.rb
      create  config/environment.rb
      create  config/environments
      create  config/environments/development.rb
      create  config/environments/production.rb
      create  config/environments/test.rb
      create  config/initializers
      create  config/initializers/backtrace_silencers.rb
      create  config/initializers/inflections.rb
      create  config/initializers/mime_types.rb
      create  config/initializers/secret_token.rb
      create  config/initializers/session_store.rb
      create  config/locales
      create  config/locales/en.yml
      create  config/boot.rb
      create  config/database.yml
      create  db
      create  db/seeds.rb
      create  doc
      create  doc/README_FOR_APP
      create  lib
      create  lib/tasks
      create  lib/tasks/.gitkeep
      create  log
      create  log/server.log
      create  log/production.log
      create  log/development.log
      create  log/test.log
      create  public
      create  public/404.html
      create  public/422.html
      create  public/500.html
      create  public/favicon.ico
      create  public/index.html
      create  public/robots.txt
      create  public/images
      create  public/images/rails.png
      create  public/stylesheets
      create  public/stylesheets/.gitkeep
      create  public/javascripts
      create  public/javascripts/application.js
      create  public/javascripts/controls.js
      create  public/javascripts/dragdrop.js
      create  public/javascripts/effects.js
      create  public/javascripts/prototype.js
      create  public/javascripts/rails.js
      create  script
      create  script/rails
      create  test
      create  test/performance/browsing_test.rb
      create  test/test_helper.rb
      create  test/fixtures
      create  test/functional
      create  test/integration
      create  test/unit
      create  tmp
      create  tmp/sessions
      create  tmp/sockets
      create  tmp/cache
      create  tmp/pids
      create  vendor/plugins
      create  vendor/plugins/.gitkeep

Start up the local server by running this command:

E:\p\rails\rails3rc>rails server
=> Booting WEBrick
=> Rails 3.0.0.rc application starting in development on http://0.0.0.0:3000
=> Call with -d to detach
=> Ctrl-C to shutdown server
[2010-08-21 11:48:18] INFO  WEBrick 1.3.1
[2010-08-21 11:48:18] INFO  ruby 1.9.2 (2010-08-18) [i386-mingw32]
[2010-08-21 11:48:18] INFO  WEBrick::HTTPServer#start: pid=4296 port=3000

Now you should see that familiar Welcome aboard page on http://localhost:3000/.

Now follow the Rails 3 Guide to build yourself a Rails 3 app!

clojure koans is awesome

2010-07-28T19:30:00-07:00

Update: The Clojure Koans GitHub repo moved. Instructions below have been updated.

I attended my first Chicago Clojure meetup and 8th Light’s Colin Jones introduced us to Clojure Koans, a Ruby Koans inspired set of tests to teach you Clojure, a functional programming language. After finishing the koans that night, I have a better understanding of how Clojure syntax works. You might have heard Clojure uses a lot of parentheses - it’s probably not an overstatement.

Here’s how to get started and reach your way to enlightenment.

Installation

Clojure Koans is on GitHub. First let’s do a git clone:

[~/local/git] git clone https://github.com/functional-koans/clojure-koans.git
Cloning into clojure-koans...
remote: Counting objects: 487, done.
remote: Compressing objects: 100% (210/210), done.
remote: Total 487 (delta 264), reused 487 (delta 264)
Receiving objects: 100% (487/487), 60.71 KiB, done.
Resolving deltas: 100% (264/264), done.
[~/local/git] cd clojure-koans 
[master][~/local/git/clojure-koans]

Here’s a quick look at the directory. Note: Clojure Koans is no longer a branch of Functional Koans.

[master][~/local/git/clojure-koans] ls -lah
total 64
drwxr-xr-x  10 skim  staff   340B Jan  2 12:49 ./
drwxr-xr-x  55 skim  staff   1.8K Jan  2 12:49 ../
drwxr-xr-x  13 skim  staff   442B Jan  2 12:49 .git/
-rw-r--r--   1 skim  staff    32B Jan  2 12:49 .gitignore
-rw-r--r--   1 skim  staff   3.7K Jan  2 12:49 README.md
-rw-r--r--   1 skim  staff    13K Jan  2 12:49 epl-v10.html
-rw-r--r--   1 skim  staff   504B Jan  2 12:49 ideaboard.txt
-rw-r--r--   1 skim  staff   165B Jan  2 12:49 project.clj
drwxr-xr-x  10 skim  staff   340B Jan  2 12:49 script/
drwxr-xr-x   5 skim  staff   170B Jan  2 12:49 src/

Cool, now let’s install Leiningen (pronounced ‘LINE-ing-en’) to grab the latest Clojure jar. We’ll need this jar along with JRE 1.5 or higher. Most Macs should have JRE installed by default.

To install Leiningen, simply download this script, place it in your $PATH (e.g., ~/bin) and chmod it.

I placed my copy in ~/bin and ran chmod on it.

[~/bin] ls -lah
total 48
-rw-r--r--@ 1 skim  staff   6.0K Jun 19  2010 .DS_Store
-rwxr-xr-x  1 skim  staff   221B Jun 19  2010 ack*
-rw-r--r--@ 1 skim  staff   5.6K Jan  2 13:05 lein
-rwxr-xr-x  1 skim  staff   2.2K Jun 19  2010 mvim*
[~/bin] chmod 755 lein
[~/bin] ls -lah
total 48
-rw-r--r--@ 1 skim  staff   6.0K Jun 19  2010 .DS_Store
-rwxr-xr-x  1 skim  staff   221B Jun 19  2010 ack*
-rwxr-xr-x@ 1 skim  staff   5.6K Jan  2 13:05 lein*
-rwxr-xr-x  1 skim  staff   2.2K Jun 19  2010 mvim*

Now let’s run the lein executable.

[~/bin] ./lein
Downloading Leiningen now...
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 6794k  100 6794k    0     0  1780k      0  0:00:03  0:00:03 --:--:-- 2905k
Leiningen is a build tool for Clojure.

Several tasks are available:
classpath   Show the classpath of the current project.
clean       Remove compiled artifacts and jars from project.
compile     Compile Clojure source into .class files.
deps        Download all dependencies and place them in the :library-path.
help        Display a list of tasks or help for a given task.
install     Install the current project or download the project specified.
interactive Enter interactive shell for calling tasks without relaunching JVM.
jar         Package up all the project's files into a jar file.
javac       Compile Java source files.
new         Create a new project skeleton.
plugin      Manage user-level plugins.
pom         Write a pom.xml file to disk for Maven interop.
repl        Start a repl session either with the current project or standalone.
run         Run a -main function with optional command-line arguments.
test        Run the project's tests.
test!       Run a project's tests after cleaning and fetching dependencies.
uberjar     Package up all the project's files and dependencies into a jar file.
upgrade     Upgrade Leiningen to the latest stable release.
version     Print version for Leiningen and the current JVM.

Run lein help $TASK for details.
Also available: readme, tutorial, copying, sample, and news.

Excellent, we have Leiningen installed. Now let’s go back to the clojure-koans directory and run lein deps. This will read the project.clj file to find out which dependencies it needs to install.

[master][~/local/git/clojure-koans] lein deps
Downloading: org/clojure/clojure/1.3.0-alpha3/clojure-1.3.0-alpha3.pom from central
Downloading: org/clojure/clojure/1.3.0-alpha3/clojure-1.3.0-alpha3.pom from clojure
Transferring 1K from clojure
Downloading: jline/jline/0.9.94/jline-0.9.94.pom from central
Downloading: junit/junit/3.8.1/junit-3.8.1.pom from clojure
Downloading: junit/junit/3.8.1/junit-3.8.1.pom from clojure-snapshots
Downloading: junit/junit/3.8.1/junit-3.8.1.pom from clojars
Downloading: junit/junit/3.8.1/junit-3.8.1.pom from central
Downloading: org/clojure/clojure/1.3.0-alpha3/clojure-1.3.0-alpha3.jar from central
Downloading: org/clojure/clojure/1.3.0-alpha3/clojure-1.3.0-alpha3.jar from clojure
Transferring 3528K from clojure
Downloading: jline/jline/0.9.94/jline-0.9.94.jar from central
Downloading: junit/junit/3.8.1/junit-3.8.1.jar from clojure
Downloading: junit/junit/3.8.1/junit-3.8.1.jar from clojure-snapshots
Downloading: junit/junit/3.8.1/junit-3.8.1.jar from clojars
Downloading: junit/junit/3.8.1/junit-3.8.1.jar from central
Copying 3 files to /Users/skim/local/git/clojure-koans/lib

Running Clojure Koans

Ok, now I’m not sure how this works exactly on Windows, but Mac and Linux, you should be able to run koans this way:

[master][~/local/git/clojure-koans] script/run

FAIL in clojure.lang.PersistentList$EmptyList@1 (equalities.clj:1)
We shall contemplate truth by testing reality, via equality.
expected: (= __ true)
  actual: (not (= nil true))

Great! If you read through the error message, you’ll see there’s something wrong in the equalities.clj file. All files live in the src/koans directory. Open it up, fix the tests and re-run the previous command. For the sake of showing you an example, I fixed the first test:

[master][~/local/git/clojure-koans] cat src/koans/equalities.clj 
(meditations
  "We shall contemplate truth by testing reality, via equality."
  (= true true)

  "To understand reality, we must compare our expectations against reality."
  (= __ (+ 1 1))

  "You can test equality of many things"
  (= (+ 3 4) __ (+ 2 __)))

[master][~/local/git/clojure-koans] script/run                 

FAIL in clojure.lang.PersistentList$EmptyList@1 (equalities.clj:1)
To understand reality, we must compare our expectations against reality.
expected: (= __ (+ 1 1))
  actual: (not (= nil 2))

Now fix the next test and you’ll be on your way to enlightenment.

functions.clj

If you ever get to functions.clj, tell me how you implemented the last one! Here’s mine:

  "Higher-order functions take function arguments"
  (= 25 ((fn [n f] (f n)) 5
          (fn [n] (* n n)))))

Have fun!

first look at mongodb

2010-07-15T19:00:00-07:00

Here’s what I learned from today’s experimentation with MongoDB. Kudos to 10gen for the wonderful documentation. Everything I needed to know about: from installation, to how it works, to what commands to use, were all right there in the docs. There was even a SQL to Mongo Mapping Chart that helps SQL users translate MongoDB’s commands and query statements. Here’s a SQL to Mongo mapping of the storage structure:

SQL	MongoDB
database	database
table	collection
row	document
column	field
primary key	_id

Using the mongo gem in an irb session, I learned about the classes in MongoDB.

MongoDB Class Name	Description
Mongo::Connection	Connection object holds a specific connection to the MongoDB server
Mongo::DB	Database object holds a specific database
Mongo::Collection	Collection object holds a specific collection
Mongo::Cursor	Cursor object holds a set of documents from a specified query
BSON::OrderedHash	OrderedHash object holds a document

[~] irb
ruby-1.8.7-p299 > require 'rubygems'
ruby-1.8.7-p299 > require 'mongo'
ruby-1.8.7-p299 > include Mongo
ruby-1.8.7-p299 > connection = Connection.new
ruby-1.8.7-p299 > db = connection.db('test_db')
ruby-1.8.7-p299 > collection = db.collection('test_coll')
ruby-1.8.7-p299 > collection.insert({'name' => 'sam', 'animal' => 'dog'})
ruby-1.8.7-p299 > collection.insert({'name' => 'dixie', 'animal' => 'cat', 'breed' => 'maneki neko'})
ruby-1.8.7-p299 > collection.insert({'name' => 'dixie', 'animal' => 'fish'})
ruby-1.8.7-p299 > cursor = collection.find
ruby-1.8.7-p299 > cursor.to_a[0]["name"]
 => "sam"

Note: I took out the return values for most of the commands in the IRB session.

Once you have a collection object, there are many ways to query the collection. The basic query command is the find command as shown above. Without any arguments, it returns the entire collection as a Mongo::Collection object. With arguments, you can specify which documents you want returned in a cursor (Mongo::Cursor).

Find a document object with a ‘name’ field, and ‘dixie’ value.

ruby-1.8.7-p299 > collection.find({'name' => 'dixie'})
 => <Mongo::Cursor:0x8094bb0c namespace='test_db.test_coll' @selector={"name"=>"dixie"}>

You can search using any field.

ruby-1.8.7-p299 > collection.find({'animal' => 'dog'})
 => <Mongo::Cursor:0x80949488 namespace='test_db.test_coll' @selector={"animal"=>"dog"}>

You can search against multiple fields to get a more refined search.

ruby-1.8.7-p299 > collection.find({'name' => 'dixie', 'animal' => 'fish'})
 => <Mongo::Cursor:0x809414f4 namespace='test_db.test_coll' @selector={"name"=>"dixie", "animal"=>"fish"}>

If not searching with exact values, you can use regular expressions or conditional operators.

ruby-1.8.7-p299 > collection.find({'name' => /^d/})
 => <Mongo::Cursor:0x8090b048 namespace='test_db.test_coll' @selector={"name"=>/^d/}>

I plan to write all of the possible moves in a 4x4 Tic Tac Toe game and export the collection as a *.bson file.

{'board' => [], 'best_moves' => []}

Backup to *.bson file

[~/local/mongodb/backup] mongodump --db test_db --collection test_coll
connected to: 127.0.0.1
DATABASE: test_db	 to 	dump/test_db
	test_db.test_coll to dump/test_db/test_coll.bson
		 3 objects

list of rspec built-in expectations

2010-06-29T18:30:00-07:00

Here’s the list of RSpec Built-in expectations straight off of David Chelimsky’s RSpec book.

actual.should equal(expected)
actual.should eql(expected)
actual.should == expected 

actual.should_not equal(expected)
actual.should_not eql(expected)
actual.should_not == expected

actual.should be_[predicate]
actual.should be_a_predicate
actual.should be_an_[predicate]

actual.should be_[predicate](*args)
actual.should be_a_[predicate](*args)
actual.should be_an_[predicate](*args)

actual.should_not be_[predicate]
actual.should_not be_a_[predicate]
actual.should_not be_an_[predicate]

actual.should_not be_[predicate](*args)
actual.should_not be_a_[predicate](*args)
actual.should_not be_an_[predicate](*args)

actual.should match(expected)
actual.should =~ expected

actual.should_not match(expected)
actual.should_not =~ expected

actual.should be < expected
actual.should be <= expected
actual.should be >= expected
actual.should be > expected

actual.should include(expected)
actual.should have(n).items
actual.should have_exactly(n).items
actual.should have_at_least(n).items
actual.should have_at_most(n).items

actual.should_not include(expected)
actual.should_not have(n).items
actual.should_not have_exactly(n).items

proc.should raise_error
proc.should raise_error(type)
proc.should raise_error(message)
proc.should raise_error(type, message)

proc.should_not raise_error
proc.should_not raise_error(type)
proc.should_not raise_error(message)
proc.should_not raise_error(type, message)

proc.should throw_symbol
proc.should throw_symbol(type)

proc.should_not throw_symbol
proc.should_not throw_symbol(type)

actual.should be_close(expected, delta)

actual.should_not respond_to(*messages)

actual.should satisfy { |actual| block }

actual.should_not satisfy { |actual| block }

git branching and merging

2010-06-28T08:30:00-07:00

As I aim to become better at using git, I thought I’d share how to branch, then later merge the branch on a git repo. I wanted to do this for my Tic Tac Toe project because I was going to add the Limelight UI. It’s actually fairly easy to branch and merge. I used Scott Chacon’s wonderful Git Reference website and followed his examples.

Listing current branches

Note: I’m using zsh and these dot files.

To list local branches:

[master][~/local/git/tic_tac_toe_ruby] git branch
* master

To list remote branches:

[master][~/local/git/tic_tac_toe_ruby] git branch -r
  origin/HEAD -> origin/master
  origin/master

Create a new branch, check out new branch

Here I’m going to create a branch called limelight.

[master][~/local/git/tic_tac_toe_ruby] git branch limelight
[master][~/local/git/tic_tac_toe_ruby] git branch
  limelight
* master

You might be wondering what the asterisk next to the branch name means, in this case, the asterisk next to “master”. It basically tells you which branch you checked out. You might then be wondering what “checked out” means. When you have a branch checked out, it is the active branch you are working in. git checkout command allows you to switch between the local branches available. git is smart enough to understand which folder/files are in which branch, so you do not need to create separate directories for each branch. All local branches live in the same directory! Brilliant!

So to check out the new branch (limelight), simply run this command:

[master][~/local/git/tic_tac_toe_ruby] git checkout limelight
Switched to branch 'limelight'

You could easily kill two birds with one stone and create a branch and check it out with a single command:

[master][~/local/git/tic_tac_toe_ruby] git checkout -b limelight
Switched to a new branch 'limelight'

Or kill four birds with two stones: create a remote branch, create a local branch, track the local branch with a remote branch and check out the new local branch.

This creates a copy of origin into a new remote branch:

[master][~/local/git/tic_tac_toe_ruby] git push origin origin:refs/heads/limelight
Total 0 (delta 0), reused 0 (delta 0)
To git@github.com:sl4m/tic_tic_toe_ruby.git
 * [new branch]      origin/HEAD -> limelight

[master][~/local/git/tic_tac_toe_ruby] git branch -a
master
remotes/origin/HEAD -> origin/master
remotes/origin/limelight
remotes/origin/master

This creates a local branch, tracks it with the newly created remote branch, and checks it out:

[master][~/local/git/tic_tac_toe_ruby] git checkout --track -b limelight origin/limelight
Branch limelight set up to track remote branch limelight from origin.
Switched to a new branch 'limelight'

Go have at it and start making changes to the new branch. Once you’re finished and you want to merge your changes in this branch to, let’s say, master, you’ll need to use git merge.

Merging a branch to another

git merge is super smart about detecting folder/file creates/deletes as well as modifications to existing folders/files. One of the only times where it may not quite understand what you want is when you make modifications of the same folder/file on both branches. You’ll run into merge conflicts which you can read more about here.

To merge a branch (limelight) to another (master), check out master and run git merge:

[limelight][~/local/git/tic_tac_toe_ruby] git checkout master
Switched to branch 'master'
[master][~/local/git/tic_tac_toe_ruby] git merge limelight
Updating 2083092..b7af83b
Fast-forward
 default_scene/players/combo_box.rb     |    6 --
 default_scene/players/default_scene.rb |  107 +++++++++++++++++++++++++++++++-
 default_scene/players/menu_item.rb     |    1 +
 default_scene/players/square.rb        |   35 +++++++++--
 default_scene/props.rb                 |   34 ++++++-----
 default_scene/styles.rb                |   23 +++++--
 lib/cpu_player.rb                      |    4 +-
 lib/game.rb                            |    1 +
 lib/human_player.rb                    |    5 +-
 lib/min_max_player.rb                  |   18 +++---
 lib/std_ui.rb                          |    5 ++
 lib/tic_tac_toe.rb                     |    2 +-
 production.rb                          |   18 +++---
 spec/default_scene_spec.rb             |   95 +++++++++++++++++++++++++---
 spec/menu_item_spec.rb                 |   24 +++++++
 spec/production_spec.rb                |    7 +--
 spec/square_spec.rb                    |   38 +++++++++++
 17 files changed, 352 insertions(+), 71 deletions(-)
 delete mode 100644 default_scene/players/combo_box.rb
 create mode 100644 spec/menu_item_spec.rb
 create mode 100644 spec/square_spec.rb

Now you should see the changes you made in the new branch in the branch you merged your changes. In this case, I see the changes I made in limelight in master.

Hold your horses, we’re done yet. If you run git status, you’ll see the merge took place locally, but not on your remote branches (see your remote repo).

[master][~/local/git/tic_tac_toe_ruby] git status
# On branch master
# Your branch is ahead of 'origin/master' by 4 commits.
#
nothing to commit (working directory clean)

If you notice above, it says “your branch is ahead of ‘origin/master’ by 4 commits”. If you’ve worked with git to where you committed multiple times, but not pushed your commits to your remote repo, you will see “your branch is ahead” message when running git status. So we’ll need to push the commits to the remote repo.

[master][~/local/git/tic_tac_toe_ruby] git push origin master
Total 0 (delta 0), reused 0 (delta 0)
To git@github.com:sl4m/tic_tac_toe_ruby.git
   2083092..b7af83b  master -> master

Now you’ll see the merged changes in your remote repo.

Delete a local branch and then remote branch

Finally, and optionally, you can delete your local branch if you don’t need it anymore. You can also make the change reflect on your remote repo.

To delete your local branch:

[master][~/local/git/tic_tac_toe_ruby] git branch -d limelight
Deleted branch limelight (was b7af83b).

To delete your remote branch:

[master][~/local/git/tic_tac_toe_ruby] git push origin :limelight
To git@github.com:sl4m/tic_tac_toe_ruby.git
 - [deleted]         limelight
[master][~/local/git/tic_tac_toe_ruby] git branch
* master
[master][~/local/git/tic_tac_toe_ruby] git branch -r
  origin/HEAD -> origin/master
  origin/master

Make sure to be in a different branch than the one you’re about to delete. Otherwise, git will bark at you.

[limelight][~/local/git/tic_tac_toe_ruby] git branch -d limelight
error: Cannot delete the branch 'limelight' which you are currently on.

Hope this helped. I encourage you to start branching!

jsdb - standalone javascript shell

2010-06-22T21:00:00-07:00

Earlier this year I was looking for a standalone JavaScript interpreter similar to Ruby’s IRB to mess around in JavaScript. JSDB, while it stands for JavaScript for databases, can easily be used to test JavaScript code snippets. This is a shell I always have opened when working with JavaScript. For the longest time I thought it was only available for Windows, but I found out yesterday it is platform independent and can be installed and run on Mac and Linux.

It uses the TraceMonkey JIT compiler with the SpiderMonkey JavaScript engine from Firefox 3.5. Since it’s derived from a specific JavaScript engine, code that might otherwise work on a different engine (e.g., JScript, v8), might not exactly work on this engine. There are peculiarities between JavaScript engines that give developers headaches, so let this be a warning. Otherwise, have fun with it!

tic tac toe in ruby - refactoring part 3

2010-06-18T21:00:00-07:00

The MinMaxPlayer is complete. I had trouble with the minmax algorithm and did not include tree depth as part of the logic. Now it seems to be working and I’m completely stoked. Here is the MinMaxPlayer class and its RSpec tests.

require 'player'
require 'board'
require 'ui'

class MinMaxPlayer < Player

  def initialize(piece)
    super(piece)
  end

  def get_opponent(piece)
    return piece === 'O' ? 'X' : 'O'
  end

  def evaluate_score(board, piece)
    opponent = get_opponent(piece)
    case board.winner
    when piece
      return 1
    when opponent
      return -1
    else
      return 0
    end
  end

  def get_best_move(board, piece, depth)
    if board.game_over?
      return evaluate_score(board, piece)
    else
      best_score = -999
      opponent = get_opponent(piece)
      empty_squares = board.get_empty_squares
      empty_squares.each do |s|
        temp_board = Board.new(board.to_a)
        temp_board.move(s, piece)
        score = -get_best_move(temp_board, opponent, depth + 1)
        if score > best_score
          best_score = score
          @best_move = s if depth == 1
        end
      end
      return best_score
    end
  end

  def make_move
    @ui.display_message("Player '#{@piece}' makes a move\n")
    if @board.get_empty_squares.size == @board.size
      return rand(@board.size)
    end
    get_best_move(@board, @piece, 1)
    return @best_move
  end
end

MinMaxPlayer RSpec tests.

require File.expand_path(File.dirname(__FILE__)) + "/spec_helper"
require 'min_max_player.rb'
require 'board'
require 'ui'
require 'stringio'

describe MinMaxPlayer do
  before(:each) do
    @x = 'X'
    @o = 'O'
    @b = ' '
    @ui = UI.new(StringIO.new, StringIO.new)
    @min_max = MinMaxPlayer.new(@x)
    @min_max.ui = @ui
    @board = Board.new
    @min_max.board = @board
  end

  it "should inherit from Player" do
    MinMaxPlayer.ancestors.include?(Player).should == true
  end

  it "should return correct opponent" do
    @min_max.get_opponent(@o).should == @x
    @min_max.get_opponent(@x).should == @o
  end

  it "should return 1 if Max is winner" do
    @board.move(0, @x)
    @board.move(1, @x)
    @board.move(2, @x)
    @min_max.evaluate_score(@board, @x).should == 1
  end

  it "should return -1 if Min is winner" do
    @board.move(0, @o)
    @board.move(1, @o)
    @board.move(2, @o)
    @min_max.evaluate_score(@board, @x).should == -1
  end

  it "should return -1 if Max is winner (from Min POV)" do
    @board.move(0, @x)
    @board.move(1, @x)
    @board.move(2, @x)
    @min_max.evaluate_score(@board, @o).should == -1
  end

  it "should return 1 if Min is winner (from Min POV)" do
    @board.move(0, @o)
    @board.move(1, @o)
    @board.move(2, @o)
    @min_max.evaluate_score(@board, @o).should == 1
  end

  it "should return 0 if no one is winner" do
    board = Board.new([@x, @x, @o, @o, @x, @x, @x, @o, @o])
    @min_max.evaluate_score(board, @x).should == 0
  end

  it "should make winning move" do
    @board.move(0, @x)
    @board.move(1, @o)
    @board.move(2, @x)
    @board.move(3, @o)
    @board.move(4, @x)
    @board.move(5, @o)
    @board.move(6, @o)

    @min_max.make_move.should == 8
  end

  it "should make winning move 2" do
    @board.move(0, @x)
    @board.move(1, @o)
    @board.move(2, @x)
    @board.move(3, @o)

    @min_max.make_move.should == 4
  end

  it "should make winning move 3" do
    @board.move(0, @o)
    @board.move(1, @x)
    @board.move(3, @o)
    @board.move(4, @o)
    @board.move(6, @x)
    @board.move(7, @x)

    @min_max.make_move.should == 8
  end

  it "should make blocking move, scenario 1" do
    @board.move(0, @x)
    @board.move(3, @o)
    @board.move(4, @o)
    @min_max.make_move.should == 5
  end

  it "should make winning move, scenario 3" do
    @board.move(0, @x)
    @board.move(1, @o)
    @board.move(2, @x)
    @board.move(3, @o)
    @board.move(5, @o)
    @board.move(7, @x)

    @min_max.make_move.should == 4
  end

  it "should not make secret losing move" do
    @board.move(0, @x)
    @board.move(4, @o)
    @board.move(8, @o)

    @min_max.make_move.should == 2
  end
end

tic tac toe in ruby - refactoring part 2

2010-06-13T21:00:00-07:00

Over the weekend, I spent more time refactoring my Tic Tac Toe program. It now looks completely different from the original source code. I attempted to use TDD 100% of the time, and I found myself using it almost all the time. It took some time getting used to writing tests first, but once I got the hang of it, it felt comfortable. There’s still a lot of work to do, but here is the main file along with some tests. You can see the rest of the source code on my GitHub repo.

# move positions
#
#  0 | 1 | 2
# ---+---+---
#  3 | 4 | 5
# ---+---+---
#  6 | 7 | 8

require 'game'
require 'human_player'
require 'cpu_player'

class TicTacToe
  attr_reader :std_in, :std_out, :player1, :player2, :game
  def initialize(*args)
    @std_in = STDIN
    @std_out = STDOUT
    @std_in = args[0] if args.size > 0
    @std_out = args[1] if args.size > 0
  end

  def ask_for_player(piece)
    player_type = ""
    loop do
      @std_out.print "\nChoose player type for '#{piece}' ('h' for human or 'c' for cpu) "
      player_type = @std_in.gets.chomp
      break if player_type == "h" || player_type == "c"
    end
    if player_type == 'h'
      HumanPlayer.new(piece, @std_in, @std_out)
    else
      CpuPlayer.new(piece)
    end
  end

  def choose_players
    @player1 = ask_for_player('O')
    @player2 = ask_for_player('X')
  end
  
  def play
    loop do
      choose_players
      @game = Game.new(player1, player2, @std_out)
      @game.play
      play_again = ''
      loop do
        @std_out.print "\nDo you want to play again? ('y' or 'n') "
        play_again = @std_in.gets.chomp
        break if play_again == 'y' || play_again == 'n'
      end
      break if play_again == 'n'
    end
    @std_out.print "\nThanks for playing!"
  end
end

if $0 == __FILE__
  TicTacToe.new.play
end

The RSpec tests

# tictactoe_spec.rb
require File.expand_path(File.dirname(__FILE__)) + "/spec_helper"
require 'tictactoe'
require 'stringio'
require 'human_player'
require 'cpu_player'

describe TicTacToe do
  before(:each) do
    @std_in = StringIO.new
    @std_out = StringIO.new
    @ttt = TicTacToe.new(@std_in, @std_out)
  end
  
  it "should be able to create a new instance" do
    lambda { TicTacToe.new }.should_not raise_error
  end

  it "should allow change to stdin" do
    ttt = TicTacToe.new
    ttt.std_in.should == STDIN
    @ttt.std_in.should == @std_in
  end

  it "should allow change to stdout" do
    ttt = TicTacToe.new
    ttt.std_out.should == STDOUT
    @ttt.std_out.should == @std_out
  end

  it "should return player" do
    @ttt.std_in.string = "h"
    @ttt.ask_for_player('O').instance_of?(HumanPlayer)
    @ttt.std_in.string = "c"
    @ttt.ask_for_player('X').instance_of?(CpuPlayer)
  end
end

tic tac toe in ruby - refactoring part 1

2010-06-09T14:00:00-07:00

One of the many refactoring techniques I can apply to my smelly Tic Tac Toe code is Extract Class. One of the 8th Lighters pointed me to Martin Fowler’s book “Refactoring” which lists a good number of refactoring techniques. In short, Extract Class refactoring is used to extract methods from an overweight class that has lost its purpose to a new class. I used this refactoring to extract methods that had reference to the board. While it’s not a significant change, it helped me understand how to use RSpec and drive the code via TDD. Here’s the code. It is also on GitHub.

# move positions
#
#  0 | 1 | 2
# ---+---+---
#  3 | 4 | 5
# ---+---+---
#  6 | 7 | 8

class TicTacToe
  module Patterns
    Winning = 
      [[(/ OO....../),0],[(/O..O.. ../),6],
       [(/......OO /),8],[(/.. ..O..O/),2],
       [(/ ..O..O../),0],[(/...... OO/),6],
       [(/..O..O.. /),8],[(/OO ....../),2],
       [(/ ...O...O/),0],[(/..O.O. ../),6],
       [(/O...O... /),8],[(/.. .O.O../),2],
       [(/O O....../),1],[(/O.. ..O../),3],
       [(/......O O/),7],[(/..O.. ..O/),5],
       [(/. ..O..O./),1],[(/... OO.../),3],
       [(/.O..O.. ./),7],[(/...OO .../),5]]
    Blocking = 
      [[(/  X . X  /),1],[(/ XX....../),0],[(/X..X.. ../),6],
       [(/......XX /),8],[(/.. ..X..X/),2],[(/ ..X..X../),0],
       [(/...... XX/),6],[(/..X..X.. /),8],[(/XX ....../),2],
       [(/ ...X...X/),0],[(/..X.X. ../),6],[(/X...X... /),8],
       [(/.. .X.X../),2],[(/X X....../),1],[(/X.. ..X../),3],
       [(/......X X/),7],[(/..X.. ..X/),5],[(/. ..X..X./),1],
       [(/... XX.../),3],[(/.X..X.. ./),7],[(/...XX .../),5],
       [(/ X X.. ../),0],[(/ ..X.. X /),6],[(/.. ..X X /),8],
       [(/ X ..X.. /),2],[(/  XX.. ../),0],[(/X.. .. X /),6],
       [(/.. .XX   /),8],[(/X  ..X.. /),2],[(/ X  ..X../),0],
       [(/ ..X..  X/),6],[(/..X..  X /),8],[(/X  ..X.. /),2]]
  end
 
  class Board
    module Pattern
      Won = 
        [[(/OOO....../),:O], [(/...OOO.../),:O],
         [(/......OOO/),:O], [(/O..O..O../),:O],
         [(/.O..O..O./),:O], [(/..O..O..O/),:O],
         [(/O...O...O/),:O], [(/..O.O.O../),:O],
         [(/XXX....../),:X], [(/...XXX.../),:X],
         [(/......XXX/),:X], [(/X..X..X../),:X],
         [(/.X..X..X./),:X], [(/..X..X..X/),:X],
         [(/X...X...X/),:X], [(/..X.X.X../),:X]]
    end
    
    attr_reader :board
    attr_reader :winner

    def initialize
      @board = [].fill(0, 9) { " " }
    end

    def occupied?(space)
      if valid_move?(space)
        return (@board.at(space) == " ") ? false : true
      end
      false
    end

    def valid_move?(space)
      (0..8) === space
    end

    def move(space, piece)
      if valid_move?(space)
        @board.delete_at(space)
        @board.insert(space, piece)
      end
    end

    def display
      print "\n\n"
      print " #{@board[0]} |"
      print " #{@board[1]} |"
      print " #{@board[2]}"		
      print "\n---+---+---\n"
      print " #{@board[3]} |"
      print " #{@board[4]} |"
      print " #{@board[5]}"
      print "\n---+---+---\n"
      print " #{@board[6]} |"
      print " #{@board[7]} |"
      print " #{@board[8]}"
      print "\n\n"
    end

    def someone_win?
      array = Pattern::Won.find { |p| p.first =~ @board.join }
      if array
        @winner = (array.last === :X) ? 'X' : 'O'
        return true
      end
      false
    end
  end

  def initialize
    @board = Board.new
    @players = { :X => 'X', :O => 'O' }
    @turn = :X
  end
  
  def play
    winner_flag = false
    9.times do
      if @turn === :X
        @board.display
        player_move
      else
        cpu_move
      end				
      if @board.someone_win?
        @board.display
        print "\n#{@board.winner} is the winner!\n"
        winner_flag = true
        break
      end
      @turn = (@turn === :X) ? :O : :X
    end
    if (!winner_flag)
      @board.display
      print "\nGame is a draw.\n"
    end	
  end
  
  private
  def player_move
    print "Enter your move [0-8]: "
    move_pos = gets.chomp.to_i
    if !@board.valid_move?(move_pos)
      print "\nInvalid move: #{move_pos}. Please re-enter.\n"
      player_move
      return
    end
    if @board.occupied?(move_pos)
      print "\nSpace is already occupied. Please re-enter.\n"
      player_move
      return
    end
    @board.move(move_pos, 'X')
  end
  
  def cpu_move
    move_pos = get_winning_pattern_move
    if move_pos.nil?
      move_pos = get_blocking_pattern_move
      if move_pos.nil?
        move_pos = get_first_available_move
      end
    end
    @board.move(move_pos, 'O')
  end
  
  def get_winning_pattern_move
    move_pos = nil
    array = Patterns::Winning.find { |p| p.first =~ @board.board.join }
    unless array.nil?
      move_pos = array.last
    end
    move_pos
  end
  
  def get_blocking_pattern_move
    move_pos = nil
    array = Patterns::Blocking.find { |p| p.first =~ @board.board.join }
    unless array.nil?
      move_pos = array.last
    end
    move_pos
  end
  
  def get_first_available_move
    if !@board.occupied?(4) 
      move_pos = 4
    else
      move_pos = @board.board.index(' ')
    end
    move_pos
  end
end

if $0 == __FILE__
  print "\n\nYou are X.  Please go first."
  TicTacToe.new.play
end

Here are the tests.

# tictactoe_spec.rb
require 'tictactoe'

describe TicTacToe::Board, "#valid_move?" do
  it "returns true if move is 0-8" do
    board = TicTacToe::Board.new
    (0..8).each do
      |s| board.valid_move?(s).should == true
    end
  end

  it "returns false if move is not 0-8" do
    board = TicTacToe::Board.new
    board.valid_move?(9).should == false
  end
end

describe TicTacToe::Board, "#move" do
  it "occupies space if move is made within valid range" do
    board = TicTacToe::Board.new
    board.move(0, 'X')
    board.occupied?(0).should == true
  end

  it "does not occupy space if move is made not within range" do
    board = TicTacToe::Board.new
    board.move(9, 'X')
    board.occupied?(9).should == false
  end
end

describe TicTacToe::Board, "#someone_win?" do
  it "returns true if it finds match from pattern set" do
    board = TicTacToe::Board.new
    board.move(0, 'X')
    board.move(1, 'X')
    board.move(2, 'X')
    board.someone_win?.should == true
  end
end

software apprenticeship

2010-05-21T10:00:00-07:00

Last week, I accepted a software apprenticeship offer at 8th Light and will be starting next month. It’s really exciting to be the worst again and I look forward to the challenges ahead. I plan to write about my experience as a software apprentice in a different blog. If you’d like, bookmark the url below.

Software Apprenticeship blog

sieve of eratosthenes

2010-05-09T13:00:00-07:00

Update: Four months later, I found a bug in my code. if m < Math.sqrt(@number) should be if m <= Math.sqrt(@number)

Last week, I learned about Sieve of Eratosthenes. According to Wikipedia, it’s an ancient algorithm created by an ancient Greek mathematician, Eratosthenes, for finding all prime numbers (below 10 million).

I was asked to write the ancient algorithm in Ruby. Here is the code.

class Sieve
  attr_reader :prime_numbers
  
  def initialize(number)
    @number = number.to_i
    @prime_numbers = (2..@number).to_a
    remove_non_prime_numbers
  end

  def remove_non_prime_numbers
    @prime_numbers.each do |m|
      if m <= Math.sqrt(@number)
        @prime_numbers.each do |n|
          if m != n && n % m == 0
            @prime_numbers.delete(n)
          end
        end
      end
    end
  end
end

if $0 == __FILE__
  p = Sieve.new(ARGV[0]).prime_numbers
  puts 'There are ' + p.length.to_s + ' prime numbers: ' + p.join(', ')
end

ruby koans is awesome

2010-03-29T22:00:00-07:00

Note: The creators of Ruby Koans, Edgecase, has created a wonderful Ruby Koans website. Check it out.

Ruby Koans is a set of tests to teach you the Ruby language. I’m impressed how much I’m learning from these tests and right off the bat, it’s using Test::Unit which gives you an introduction to TDD style coding.

How to get started

The README.rdoc at Ruby Koans GitHub repo should suffice, but if that wasn’t clear, you should have the following already installed:

Ruby 1.8.6 or higher (I used 1.8.7)
msysgit, Git OSX, or zip program

Basically, do a git clone on the Ruby Koans repo (or download zip file):

git clone git://github.com/edgecase/ruby_koans.git
Initialized empty Git repository in E:/p/git/fake/ruby_koans/.git/
remote: Counting objects: 294, done.
remote: Compressing objects: 100% (286/286), done.
remote: Total 294 (delta 184), reused 0 (delta 0)
Receiving objects: 100% (294/294), 51.84 KiB, done.
Resolving deltas: 100% (184/184), done.

Done. Get out your favorite editor (or IDE) and have a command prompt|shell or two ready. You want to first run path_to_enlightenment.rb:

ruby path_to_enlightenment.rb

Thinking AboutAsserts
  test_assert_truth has damaged your karma.

You have not yet reached enlightenment ...
<false> is not true.

Please meditate on the following code:
./about_asserts.rb:10:in `test_assert_truth'
path_to_enlightenment.rb:28


mountains are merely mountains

Open about_asserts.rb and look up the test method called test_assert_truth and fix whatever is wrong with it. The tests will give you hints, so don’t worry, you’ll figure it out. Once you do, save the file, re-run path_to_enlightenment.rb.

ruby path_to_enlightenment.rb

Thinking AboutAsserts
  test_assert_truth has expanded your awareness.
  test_assert_with_message has damaged your karma.

You have not yet reached enlightenment ...
This should be true -- Please fix this.
<false> is not true.

Please meditate on the following code:
./about_asserts.rb:16:in `test_assert_with_message'
path_to_enlightenment.rb:28


learn the rules so you know how to break them properly

You will now see that test_assert_truth has expanded your awareness. Now go on to the next test and fix the problem in there. Rinse and repeat.

If you ever get up to about_scoring_project.rb, please let me know how you implemented the score method. Here’s mine:

def score(dice)
  total = 0
  rolls = dice.dup
  return total if rolls.size == 0
  (1..6).each do |i| 
    if rolls.count(i) >= 3
      3.times do
        rolls.delete_at(rolls.index(i))
      end
      total += (i == 1) ? 1000 : 100*i
    end
  end
  rolls.each do |i|
    if i == 1
      total += 100
    elsif i == 5
      total += 50
    end
  end
  total
end

I added additional tests just for the heck of it:

  def test_other_oddities
    assert_equal 1100, score([1,1,1,1])
    assert_equal 1200, score([1,1,1,1,1])
    assert_equal 600, score([5,5,5,5,5])
  end

Here’s my Proxy class from about_proxy_object_project.rb:

class Proxy
  attr_reader :messages

  def initialize(target_object)
    @object = target_object
    @messages = []
  end

  def method_missing(method_name, *args, &block)
    @messages.push(method_name)
    @object.__send__(method_name, *args)
  end

  def called?(message)
    return true unless @messages.index(message).nil?
    false
  end

  def number_of_times_called(message)
    return @messages.count(message)
  end
end

Have fun!

ruby vs. javascript - quick comparison

2010-03-20T20:30:00-07:00

These are my initial observations between the two languages so far.

nil and null

Ruby

nil.is_a?(Object) # true

JavaScript

typeof null === "object" // true

Unlike Ruby, null is not derived from a class (or object), but is a special value, so it does not have any members. typeof returns “object” for backward compatibility reasons.

falsy values

In Ruby, zero and empty strings are considered truthy values.

Ruby

status = (nil) ? true : false   # status = false
status = (false) ? true : false # status = false

JavaScript

var status;
status = (null) ? true : false;      // status = false
status = (false) ? true : false;     // status = false
status = (0) ? true : false;         // status = false
status = ("") ? true : false;        // status = false
status = ('') ? true : false;        // status = false
status = (undefined) ? true : false; // status = false

strings

Both Ruby and JavaScript use single and double quotes for creating strings. You can also use single quotes in double quotes and vice versa without the need to escape them. However, Ruby has some powerful flexible quoting features.

Ruby

a = %(hello world)  # "hello world"
b = %!hello world!  # "hello world"
c = %{hello world}  # "hello world"
d = %Q{hello world} # "hello world"
e = %{
hello
world
}                   # "\nhello\nworld\n"

Ruby supports heredocs.

Ruby

f = <<EOS
hello
world
EOS

Ruby uses the shovel operator to modify original strings.

Ruby

string = "hello"
new_string = string
new_string << " world"  # "hello world" (appends ' world' to new_string)
string == "hello world" # true (modified original string)

Ruby does not interpret escape characters when using single quotes (except itself). JavaScript always interprets.

Ruby

"\n".size   # 1
'\n'.size   # 2
'\''        # "'"

JavaScript

"\n".length // 1
'\n'.length // 1
'\''        // "'"

Ruby has some other features.

Ruby

number = 21
string = "Your lucky number today is #{number}" # "Your lucky number today is 21"
                                                # (string interpolation only works for double quoted strings)

string[5,5]  # 'lucky' (substring)
string[5..9] # 'lucky'

arrays

Ruby has some really cool shorthand methods.

Ruby

array = []
array << 'a'                  # shovel operator acts like JavaScript's push method
array[1] = 'b'
array.push('c')
array.size                    # 3 (Ruby also has length like JavaScript)
array.first                   # "a" (first element)
array.last                    # "c" (last element)
array[-1]                     # "c" (walks backwards)
array[-3]                     # "a"
array[0,1]                    # ["a"] (acts like JavaScript's slice method)
array[1,2]                    # ["b", "c"]
array[0..2]                   # ["a", "b", "c"] (between index 0 and 2, inclusive)
first, second, third = array  # first => "a", second => "b", third => "c"
another_array = %w(a b c)     # ["a", "b", "c"] (equivalent to String#split)
array == another_array        # true
array - %w(a b)               # ["c"] (returns the difference between both arrays)

Resources

tic tac toe in ruby and javascript

2010-03-15T23:55:00-07:00

Note: The latest Ruby source can be found here and JavaScript source here

The Challenge

I was “challenged” by someone last week to build a tic tac toe game that should consist of the following:

human vs. computer
some form of user interface (text-based is ok)
computer can never lose, only draw
can be written in any programming language

I don’t recall the last time I created a game, let alone a game with some form of AI. So what would any person like me do? Search on Google of course. I used keywords like tic tac toe algorithm, tic tac toe AI, and discovered different ways people solved the problem.

My friend who works for Siemens, told me to use a library he uses at work called rl-library. It is a Reinforcement Learning library that is capable of ‘learning’ based on user-defined environments. I found the framework to be very fascinating but I thought it would make the challenge too easy, so I had to opt out (I did add the Reinforcement Learning book to my wish list though). I told him I wanted to avoid all external libraries and he thought about another way. For the next several hours, we sat down together via Skype, sharing his screen to show me how to develop a table of all possible moves in memory. I mean it’s only 9! (or 362,880) possibilities which will consume some megabytes of memory. So by the end of the night, we had some code in Java and I needed to complete the state/action piece for this table to be useful - in other words, after the table has been created, I needed to determine which move was the best move (from the computer standpoint).

I was at a loss. I think it was easy for my friend since he thinks in RL, but I couldn’t figure it out right away. So off to Google I went again, looking for another solution. I found several search results and ended up finding what became my solution. I never looked at Tic Tac Toe beyond the rules and playing the game, so it was interesting to learn about the algorithm that the computer would use. This solution basically had a similar table, but not all 362,880 possibilities. It used pattern sets in regular expressions to look for a winning move or a blocking move. Storing these patterns in arrays of arrays, yielded the Ruby code below.

Tic Tac Toe in Ruby

Update: This code is old and has been replaced. See the latest here.

# move positions
#
#  0 | 1 | 2
# ---+---+---
#  3 | 4 | 5
# ---+---+---
#  6 | 7 | 8

class TicTacToe
  module Patterns
    Winning = 
      [[(/ OO....../),0],[(/O..O.. ../),6],
       [(/......OO /),8],[(/.. ..O..O/),2],
       [(/ ..O..O../),0],[(/...... OO/),6],
       [(/..O..O.. /),8],[(/OO ....../),2],
       [(/ ...O...O/),0],[(/..O.O. ../),6],
       [(/O...O... /),8],[(/.. .O.O../),2],
       [(/O O....../),1],[(/O.. ..O../),3],
       [(/......O O/),7],[(/..O.. ..O/),5],
       [(/. ..O..O./),1],[(/... OO.../),3],
       [(/.O..O.. ./),7],[(/...OO .../),5]]
    Blocking = 
      [[(/  X . X  /),1],[(/ XX....../),0],[(/X..X.. ../),6],
       [(/......XX /),8],[(/.. ..X..X/),2],[(/ ..X..X../),0],
       [(/...... XX/),6],[(/..X..X.. /),8],[(/XX ....../),2],
       [(/ ...X...X/),0],[(/..X.X. ../),6],[(/X...X... /),8],
       [(/.. .X.X../),2],[(/X X....../),1],[(/X.. ..X../),3],
       [(/......X X/),7],[(/..X.. ..X/),5],[(/. ..X..X./),1],
       [(/... XX.../),3],[(/.X..X.. ./),7],[(/...XX .../),5],
       [(/ X X.. ../),0],[(/ ..X.. X /),6],[(/.. ..X X /),8],
       [(/ X ..X.. /),2],[(/  XX.. ../),0],[(/X.. .. X /),6],
       [(/.. .XX   /),8],[(/X  ..X.. /),2],[(/ X  ..X../),0],
       [(/ ..X..  X/),6],[(/..X..  X /),8],[(/X  ..X.. /),2]]
    Won = 
      [[(/OOO....../),:O], [(/...OOO.../),:O],
       [(/......OOO/),:O], [(/O..O..O../),:O],
       [(/.O..O..O./),:O], [(/..O..O..O/),:O],
       [(/O...O...O/),:O], [(/..O.O.O../),:O],
       [(/XXX....../),:X], [(/...XXX.../),:X],
       [(/......XXX/),:X], [(/X..X..X../),:X],
       [(/.X..X..X./),:X], [(/..X..X..X/),:X],
       [(/X...X...X/),:X], [(/..X.X.X../),:X]] 
  end
  
  def initialize
    @board = [].fill(0, 9) { " " }
    @players = { :X => 'X', :O => 'O' }
    @turn = :X
  end
  
  def play
    winner_flag = false
    9.times do
      if @turn === :X
        display
        player_move
      else
        cpu_move
      end				
      winner = someone_win?
      unless winner.nil?
        display
        print "\n#{winner} is the winner!\n"
        winner_flag = true
        break
      end
      @turn = (@turn === :X) ? :O : :X
    end
    if (!winner_flag)
      display
      print "\nGame is a draw.\n"
    end	
  end
  
  private
  def player_move
    print "Enter your move [0-8]: "
    move_pos = gets.chomp.to_i
    unless (0..8) === move_pos
      print "\nInvalid move: #{move_pos}. Please re-enter.\n"
      player_move
      return
    end
    if @board.at(move_pos) != ' '
      print "\nSpace is already occupied. Please re-enter.\n"
      player_move
      return
    end
    move move_pos, 'X'
  end
  
  def cpu_move
    move_pos = get_winning_pattern_move
    if move_pos.nil?
      move_pos = get_blocking_pattern_move
      if move_pos.nil?
        move_pos = get_first_available_move
      end
    end
    move move_pos, 'O'
  end
  
  def move(pos, piece)
    @board.delete_at(pos)
    @board.insert(pos, piece)
  end
  
  def display
    print "\n\n"
    print " #{@board[0]} |"
    print " #{@board[1]} |"
    print " #{@board[2]}"		
    print "\n---+---+---\n"
    print " #{@board[3]} |"
    print " #{@board[4]} |"
    print " #{@board[5]}"
    print "\n---+---+---\n"
    print " #{@board[6]} |"
    print " #{@board[7]} |"
    print " #{@board[8]}"
    print "\n\n"
  end
  
  def someone_win?
    symbol = nil
    array = Patterns::Won.find { |p| p.first =~ @board.join }
    unless array.nil?
      symbol = (array.last === :X) ? 'X' : 'O'
    end
    symbol
  end		
  
  def get_winning_pattern_move
    move_pos = nil
    array = Patterns::Winning.find { |p| p.first =~ @board.join }
    unless array.nil?
      move_pos = array.last
    end
    move_pos
  end
  
  def get_blocking_pattern_move
    move_pos = nil
    array = Patterns::Blocking.find { |p| p.first =~ @board.join }
    unless array.nil?
      move_pos = array.last
    end
    move_pos
  end
  
  def get_first_available_move
    if @board.at(4) == ' '
      move_pos = 4
    else
      move_pos = @board.index(' ')
    end
    move_pos
  end
end

if $0 == __FILE__
  print "\n\nYou are X.  Please go first."
  TicTacToe.new.play
end

I initially began writing the game in JavaScript, but couldn’t figure out a way to display the board in the console without having to deal with the browser. Luckily, I was pointed in the right direction and used Node.js (sadly does not work on Windows). It handled the stdout/stdin just fine. I had to fiddle around with stdin by using Node’s process object and add a listener for stdin. It wasn’t immediately intuitive how the listener worked, but I was able to finally get it to prompt for user input multiple times to play the game.

Tic Tac Toe in JavaScript

/**
  move positions

   0 | 1 | 2
  ---+---+---
   3 | 4 | 5
  ---+---+---
   6 | 7 | 8

*/

exports.game = function() {
  var sys = require('sys');
  var WinningPatterns =
    [[(/ OO....../),0],[(/O..O.. ../),6],
     [(/......OO /),8],[(/.. ..O..O/),2],
     [(/ ..O..O../),0],[(/...... OO/),6],
     [(/..O..O.. /),8],[(/OO ....../),2],
     [(/ ...O...O/),0],[(/..O.O. ../),6],
     [(/O...O... /),8],[(/.. .O.O../),2],
     [(/O O....../),1],[(/O.. ..O../),3],
     [(/......O O/),7],[(/..O.. ..O/),5],
     [(/. ..O..O./),1],[(/... OO.../),3],
     [(/.O..O.. ./),7],[(/...OO .../),5]];
  
  var BlockingPatterns = 
    [[(/  X . X  /),1],[(/ XX....../),0],[(/X..X.. ../),6],
     [(/......XX /),8],[(/.. ..X..X/),2],[(/ ..X..X../),0],
     [(/...... XX/),6],[(/..X..X.. /),8],[(/XX ....../),2],
     [(/ ...X...X/),0],[(/..X.X. ../),6],[(/X...X... /),8],
     [(/.. .X.X../),2],[(/X X....../),1],[(/X.. ..X../),3],
     [(/......X X/),7],[(/..X.. ..X/),5],[(/. ..X..X./),1],
     [(/... XX.../),3],[(/.X..X.. ./),7],[(/...XX .../),5],
     [(/ X X.. ../),0],[(/ ..X.. X /),6],[(/.. ..X X /),8],
     [(/ X ..X.. /),2],[(/  XX.. ../),0],[(/X.. .. X /),6],
     [(/.. .XX   /),8],[(/X  ..X.. /),2],[(/ X  ..X../),0],
     [(/ ..X..  X/),6],[(/..X..  X /),8],[(/X  ..X.. /),2]];
       
  var WonPatterns =
    [[(/OOO....../),'O'], [(/...OOO.../),'O'],
     [(/......OOO/),'O'], [(/O..O..O../),'O'],
     [(/.O..O..O./),'O'], [(/..O..O..O/),'O'],
     [(/O...O...O/),'O'], [(/..O.O.O../),'O'],
     [(/XXX....../),'X'], [(/...XXX.../),'X'],
     [(/......XXX/),'X'], [(/X..X..X../),'X'],
     [(/.X..X..X./),'X'], [(/..X..X..X/),'X'],
     [(/X...X...X/),'X'], [(/..X.X.X../),'X']];
  var board = [];
  for (var i=0; i<9; i+=1) {
    board.push(' ');
  }
  var X = 'X',
      O = 'O';
  var players = [X, O],
      turn = X;
      
  var moveCPU = function() {
    var movePos;
    movePos = getWinningPatternMove();
    if (movePos === -1) {
      movePos = getBlockingPatternMove();
      if (movePos === -1) {
        movePos = getFirstAvailableMove();
      }
    }
    move(movePos, O);
  };
  var move = function(pos, piece) {
    if (piece !== turn) { return false; }
    pos = Number(pos);
    if (pos >= 0 && pos <= 8 &&
      !isNaN(pos) && board[pos] === ' ') {
      board.splice(pos, 1, piece);
      turn = (piece === X) ? O : X;
      return true;
    }
    return false;
  };
  var getDisplay = function() {
    var display = 
      '\n\n' +
      ' ' + board[0] + ' |' +
      ' ' + board[1] + ' |' +
      ' ' + board[2] +
      '\n---+---+---\n' +
      ' ' + board[3] + ' |' +
      ' ' + board[4] + ' |' +
      ' ' + board[5] +
      '\n---+---+---\n' +
      ' ' + board[6] + ' |' +
      ' ' + board[7] + ' |' +
      ' ' + board[8] +
      '\n\n';
    return display;
  };
  var display = function() {
    sys.print(getDisplay());
  };
  var isBoardFilled = function() {
    var movePos = getFirstAvailableMove();
    if (movePos === -1) {
      display();
      sys.print('Game is a draw.\n');
      process.stdio.close();
      return true;
    }
    return false;
  };
  var isGameWinner = function() {
    var flatBoard = board.join(''),
        i, max = WonPatterns.length, array;
    var gameWinner;
    for (i=0; i<max; i+=1) {
      array = flatBoard.match(WonPatterns[i][0]);
      if (array) { gameWinner = WonPatterns[i][1]; }
    }
    if (gameWinner) {
      display();
      sys.print(gameWinner + ' is the winner!\n');
      process.stdio.close();
      return true;
    }
    return false;
  };
  var getWinningPatternMove = function() {
    var flatBoard = board.join(''),
        i, max = WinningPatterns.length, array;
    for (i=0; i<max; i+=1) {
      array = flatBoard.match(WinningPatterns[i][0]);
      if (array) { return WinningPatterns[i][1]; }
    }
    return -1;
  };
  var getBlockingPatternMove = function() {
    var flatBoard = board.join(''),
        i, max = BlockingPatterns.length, array;
    for (i=0; i<max; i+=1) {
      array = flatBoard.match(BlockingPatterns[i][0]);
      if (array) { return BlockingPatterns[i][1]; }
    }
    return -1;
  };
  var getFirstAvailableMove = function() {
    if (board[4] === ' ') {
      return 4;
    }
    return board.indexOf(' ');
  };
  return {
    play: function() {
      display();
      sys.print("Enter your move [0-8]: ");
      process.stdio.addListener('data', function(response) {
        if (move(response, X)) {
          if (!isGameWinner() && !isBoardFilled()) {
              moveCPU();
              if (!isGameWinner()) {
                display();
                sys.print("Enter your move [0-8]: ");
              }
          }
        } else {
          sys.print("\nI'm sorry Dave, I'm afraid I can't do that.\n");
          sys.print("Enter your move [0-8]: ");
        }
      });
      process.stdio.open();
    },
    getBoardDisplay : function() {
      return getDisplay();
    },
    getTurn: function() {
      return turn;
    },
    getBoard: function() {
      return board.slice(0);
    },
    getCpuGamePiece: function() {
      return O;
    },
    getHumanGamePiece: function() {
      return X;
    },
    movePlayer: function(pos) {
      return move(pos, X);
    }
  };
};

Both implementations are a bit smelly. With the time I had, I tried what I could to make it less smelly. I’m also new to Ruby so I kind of have an excuse ;-). The JavaScript code is pretty much a straight port from the Ruby code, so it’ll include some of the smells. One thing I was asked to do was to create tests along with the JavaScript code*. When thinking about the tests, it made me think how testable the JavaScript TicTacToe object really was. I ended up adding more public methods to the object to allow the tests to access certain properties of the object. Had I approached the problem test first, I think it would’ve been easier to design the code.

* Of course, I was doing this all wrong from the beginning. After implementing the code, I then thought about tests which is against TDD. One of these days, I’ll need to practice TDD and make it a habit.

Tic Tac Toe Tests in JavaScript

(function() {
  var ticTacToe = require('./tic_tac_toe_node');
  var sys = require('sys');
  var assert = require('assert');

  var runTest = function(description, test) {
    sys.puts('  Testing... ' + description);
    test();
  };

  var runTestSuite = function() {
    sys.puts('\n[Test Suite starting...]\n');

    runTest('board has nine squares', function() {
      assert.strictEqual(ticTacToe.game().getBoard().length,
        9, 'board does not have nine squares');
    });
    runTest('cpu player is O', function() {
      assert.strictEqual(ticTacToe.game().getCpuGamePiece(),
        'O', 'cpu player is not O');
    });
    runTest('human player is X', function() {
      assert.strictEqual(ticTacToe.game().getHumanGamePiece(),
        'X', 'human player is not X');
    });
    runTest('human player starts first', function() {
      assert.strictEqual(ticTacToe.game().getTurn(), 'X',
        'human player is not going first');
    });
    runTest('move human player piece within range [0-8]', function() {
      assert.strictEqual(ticTacToe.game().movePlayer(4), true,
        'could not move piece to position [4]');
    });
    runTest('move human player piece outside of range (lower bound)',
      function() {
        assert.strictEqual(ticTacToe.game().movePlayer(-1), false,
          'was allowed to move piece to position [-1]');
      });
    runTest('move human player piece outside of range (upper bound)',
      function() {
        assert.strictEqual(ticTacToe.game().movePlayer(9), false,
          'was allowed to move piece to position [9]');
      });
    runTest('move human player piece on same square', function() {
      var game = ticTacToe.game();
      game.movePlayer(0);
      assert.strictEqual(game.movePlayer(0), false,
        'was allowed to move piece to same square twice');
    });
    sys.puts('\n[Test Suite finished!]\n');
  };

  var runGame = function() {
    ticTacToe.game().play();
  };

  // run tests
  runTestSuite();

  // run the game
  runGame();

})();

If you’re thinking why the JavaScript version of Tic Tac Toe isn’t running on Node.js, it’s because it needs to be ‘required’ from another file due to the CommonJS module system. Just save the JavaScript TicTacToe code as tic_tac_toe_node.js and JavaScript test code as tic_tac_toe_node_test.js in the same folder, and run the test code:

node tic_tac_toe_node_test.js

It should run the small test suite and execute the game. It’s very simple, so it will end after a game. You’ll have to run the test again to run multiple games.

Final Thoughts

It’s amazing how much I’ve learned from this challenge. A few things to take away from this experience:

Practice, practice, practice!
Build more breakable toys

More often than not, I read material, but never apply it right away or practice them. I need to be more hands-on and take on more challenges to apply what I’ve learned. Another experiment I tried was using the pomodoro technique using Chromodoro. By creating time-boxed sessions, I was able to focus on a single task at a time. It really helped and I will start using it for other needs.

how to make github and proxy play nicely with ssh

2010-02-22T22:00:00-08:00

Update (06/30/2010): This method may no longer work with the newer msysgit versions. Since I’m no longer with the company that had a proxy implemented, I’m not able to test out the setup.

Update: Scott Chacon recently posted about Smart HTTP transport which is basically the ability to perform git commands over HTTP with authentication, but unfortunately, it only works for git clients version 1.6.6 and above. msysgit (Git for Windows) is currently on version 1.6.5.1. I will write a post about it once there’s a new version of msysgit. Git for OS X has the supported clients.

Jeff Tchang does a pretty nice job explaining how to use git commands via SSH through the corporate proxy on Unix and Windows. I’m just going to fill in a few missing gaps. This is a straight guide for making git work on Windows in your corporate environment.

What You’ll Need

msysgit (I used 1.6.5.1)
connect.c binary

Installation

Install msysgit with OpenSSH option (should be the last one in red). Follow these instructions (if you have not already) to generate SSH keys. If you prefer the command prompt like me (help guide uses cygwin aka Git Bash), then follow these simple instructions:

Open command prompt (cmd.exe)
Navigate to %HOME%

C:\Windows\System32>cd %HOME%

C:\Users\skim>

Enter the following:

C:\Users\skim>ssh-keygen -t rsa -C "email@address.com"

where “email@address.com” is your own email address linked to your GitHub account.

It will now prompt you for a filename, simply press Enter
Now it will ask you for a passphrase. Now for the sake of simplicity, I’m not going to enter a passphrase, but you should read this help guide on why you should use a passphrase.
Re-enter your passphrase (in my case, I left it empty and pressed Enter)

C:\Users\skim>ssh-keygen -t rsa -C "email@address.com"
Generating public/private rsa key pair.
Enter file in which to save the key (/c/Users/skim/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /c/Users/skim/.ssh/id_rsa.
Your public key has been saved in /c/Users/skim/.ssh/id_rsa.pub.
The key fingerprint is:
e8:ae:60:8f:38:c2:98:1d:6d:84:60:8c:9e:dd:47:81 email@address.com

At this point, it created two important files under %HOME%\.ssh : id_rsa and id_rsa.pub

C:\Users\skim>dir .ssh
 Volume in drive C has no label.
 Volume Serial Number is 4C30-D3E0

 Directory of C:\Users\skim\.ssh

02/07/2010  07:43 PM    <DIR>          .
02/07/2010  07:43 PM    <DIR>          ..
02/06/2010  11:10 PM             1,675 id_rsa
02/06/2010  11:10 PM               399 id_rsa.pub
02/07/2010  07:43 PM               407 known_hosts
               3 File(s)          2,481 bytes
               2 Dir(s)  11,605,680,128 bytes free

The content of id_rsa.pub will be used to add a public key to your SSH public keys list on your GitHub account. This will allow you to talk to your GitHub repositories from the very computer you are using now. Make sure you have done this.

The other file, id_rsa will be used to allow access to your GitHub repositories via SSH/proxy.

Under %HOME%\.ssh, create a new file called config and add the following:

ProxyCommand C:/git/bin/connect.exe -H username@proxy.example.com:443 %h %p

Host github.com
User git
Port 22
Hostname github.com
IdentityFile "C:\Users\skim\\.ssh\id_rsa"
TCPKeepAlive yes
IdentitiesOnly yes

Host ssh.github.com
User git
Port 443
Hostname ssh.github.com
IdentityFile "C:\Users\skim\\.ssh\id_rsa"
TCPKeepAlive yes
IdentitiesOnly yes

Make sure to change the following in the above commands to match your environment:

Change C:/git/bin/connect.exe to where you placed connect.exe. Make sure it’s in PATH environment variable. It’s important the slashes in the path are in fact forward slashes. This was discussed in Jeff Tchang’s article
Change username@proxy.example.com:443 to your proxy address. If you don’t require username/password just enter the address (e.g., proxy.example.com:443). Make sure the port is the port number of your corporate environment’s proxy. It doesn’t have to be 443.
Change both C:\Users\skim\.ssh\id_rsa paths to your specific %HOME%\.ssh\id_rsa path. It’s important the path contains id_rsa and not id_rsa.pub

Testing It Out

Assuming _Your_Git_Path_\bin\ folder is in your PATH environment variable, try running the following command:

C:\Users\skim>ssh -F %HOME%\skim\.ssh\config github.com

ERROR: Hi sl4m! You've successfully authenticated, but GitHub does not provide shell access

Connection to github.com closed.

The error is expected since GitHub does not allow shell access. What is most important is that you see the “successfully authenticated” message.

Now that you’re all set, you can run git commands. It’s slightly different from the git commands you might be used to (if you’re familiar with git already). When you clone a repository, you typically invoke this command:

git clone git://github.com/rails/rails.git

But with SSH, this is how you invoke the same command:

git clone ssh://git@github.com:443/rails/rails.git

Follow the pattern and you should be able to run all git commands via SSH/proxy.

my rails mentor project - the beginning

2010-02-18T18:30:00-08:00

I mentioned in my previous post that I requested a mentorship with Kris at Rails Mentors. I was fortunate he accepted my request and I spoke to him over the weekend via Skype to discuss about what I want to get out of this mentorship. I told him I wanted to start a small Rails project, specifically, build a website that can create rss feeds for rss-less websites. Kris liked the idea and created a private github repo. He sent me his environment.rb file and my job is to look into the gems he likes to use in his Rails projects.

# Be sure to restart your server when you modify this file

# Specifies gem version of Rails to use when vendor/rails is not present
RAILS_GEM_VERSION = '2.3.5' unless defined? RAILS_GEM_VERSION

# Bootstrap the Rails environment, frameworks, and default configuration
require File.join(File.dirname(__FILE__), 'boot')

Rails::Initializer.run do |config|
  # Settings in config/environments/* take precedence over those specified here.
  # Application configuration should go into files in config/initializers
  # -- all .rb files in that directory are automatically loaded.

  # Add additional load paths for your own custom dirs
  config.load_paths += %W(Rails.root.join('app', 'middleware'))

  # Specify gems that this application depends on and have them installed with rake gems:install
  config.gem 'acl9', :source => 'http://gemcutter.org'
  config.gem 'redis', :source => 'http://gemcutter.org'
  config.gem 'redis-store', :source => 'http://gemcutter.org'
  config.gem 'xapit', :source => 'http://gemcutter.org'
  config.gem 'gravtastic', :source => 'http://gemcutter.org'
  config.gem 'paperclip', :source => 'http://gemcutter.org'
  config.gem 'stringex', :source => 'http://gemcutter.org'
  config.gem 'email_veracity', :source => 'http://gemcutter.org'
  config.gem 'state_machine', :source => 'http://gemcutter.org'
  config.gem 'acts_as_tree', :source => 'http://gemcutter.org'
  config.gem 'formtastic', :source => 'http://gemcutter.org'
  config.gem 'authlogic', :source => 'http://gemcutter.org'
  config.gem 'searchlogic', :source => 'http://gemcutter.org'
  config.gem 'settingslogic', :source => 'http://gemcutter.org'
  config.gem 'hoptoad_notifier', :source => 'http://gemcutter.org'
  config.gem 'sitemap_generator', :source => 'http://gemcutter.org'
  config.gem 'validates_timeliness', :source => 'http://gemcutter.org'
  config.gem 'inherited_resources', :source => 'http://gemcutter.org'
  config.gem 'acts-as-taggable-on', :source => 'http://gemcutter.org'
  config.gem 'will_paginate', :source => 'http://gemcutter.org'
  config.gem 'bullet', :source => 'http://gemcutter.org'
  config.gem 'factory_girl', :source => 'http://gemcutter.org'
  config.gem 'rspec', :lib => false, :source => 'http://gemcutter.org'
  config.gem 'rspec-rails', :lib => false, :source => 'http://gemcutter.org'
  config.gem 'webrat', :source => 'http://gemcutter.org'
  config.gem 'cucumber', :source => 'http://gemcutter.org'

  # Only load the plugins named here, in the order given (default is alphabetical).
  # :all can be used as a placeholder for all plugins not explicitly named
  # config.plugins = [ :exception_notification, :ssl_requirement, :all ]

  # Skip frameworks you're not going to use. To use Rails without a database,
  # you must remove the Active Record framework.
  config.frameworks -= [ :active_resource ]

  # Activate observers that should always be running
  # config.active_record.observers = :cacher, :garbage_collector, :forum_observer

  # Set Time.zone default to the specified zone and make Active Record auto-convert to this zone.
  # Run "rake -D time" for a list of tasks for finding time zone names.
  config.time_zone = 'UTC'

  # The default locale is :en and all translations from config/locales/*.rb,yml are auto loaded.
  # config.i18n.load_path += Dir[Rails.root.join('my', 'locales', '*.{rb,yml}')]
  config.i18n.default_locale = :en
end

my learning resources

2010-02-17T18:30:00-08:00

There is no / one | right / way about learning. I’ve looked around the net and found these along the way:

Ruby

Books

Free e-books available online:

Unfortunately, all of these are somewhat outdated. So I chose the recently published book called “The Well Grounded Rubyist” by David A. Black. I’m not too far into it yet, but it was highly recommended and so far it’s been very helpful. It covers Ruby 1.9.1.

Let’s not forget Prag Prog’s PickAxe, “Programming Ruby 1.9” which also covers Ruby 1.9.1. This is the complete reference, so it’s nice to have by your side if you need to look up a class or two.

Gregory T. Brown is slowly releasing his book, “Ruby Best Practices” in digital form chapter by chapter for free. He already released four chapters and you can grab them here. If you like what you see so far, I highly suggest picking up the dead tree version available at O’Reilly, Amazon, or your local bookstore.

Online Courses

There is a free online Ruby course from RubyLearning which I highly recommend. Although, I have not yet completed the course, the latest course covers Ruby 1.9.1, and there are a lot of mentors willing to help in the course forum.

This is not really an online course, but a self-teaching set of tests called Ruby Koans. Follow the instructions and it will guide you to the path of enlightenment.

Online Resources

Official Ruby website
Official Ruby mailing lists
Try Ruby! (15 minute interactive tutorial)
Luis Lavena
RubyInstaller for Windows
ashbb
RubyTu.be

Rails

Books

Rails changes rapidly, so spending money on a dead-tree version of a book is probably not the best way to go. In any case, Prag Prog’s “Agile Web Development with Rails, Third Edition” is the latest book on Rails. Unfortunately it does not contain Rails 3.0, but this ongoing wiki page contains information about the beta and about Rails Fourth Edition.

O’Reilly recently announced the Live Edition of Learning Rails which will include Rails 3.x content.

There’s also a Rails 3 Upgrade Handbook by Jeremy McAnally coming out soon. Sign up here to be notified when it’s available. Update: it’s out now

Online Courses

I started using Learning Rails, a free online Ruby on Rails course. Although, it’s based on an older version of Rails, the overall information about Rails is there, especially about Model-View-Controller, scaffold, migrations, rake commands, etc.

Online Resources

Mentorship

Probably the best move I’ve made is finding a Ruby on Rails mentor at Rails Mentors. Los Angeles-based Rails developer, @kris, accepted my mentorship. We spoke this past weekend via Skype and will start on a project that will create custom feeds for RSS-less websites. It’s a private github repo as of now and we may open it up in the future, but for now, I will blog about the project here. I’m pretty excited to start this project and will hopefully learn a lot from it.

Metaprogramming

Books

Prag Prog’s Metaprogramming Ruby book by Paolo Perotta just released this month. I have this book on my wishlist and plan to pick it up when I learn about the advanced DSL concepts.

Online Courses

RubyLearning is offering an online course on Ruby Metaprogramming on March 6th. For a small fee of $5-9, you will learn about Ruby’s advanced features and start “thinking in Ruby”. Best part of all, Paolo Perotta will be answering some of the questions in the course forum. How cool is that? You can learn more about the course here.

Online Resources

Ruby Metaprogramming

Software Craftsmanship

Books

I still have much to learn in this area. To start off, however, I recommend starting from the beginning and pick up, “Apprenticeship Patterns: Guidance for the Aspiring Software Craftsman” by Dave Hoover and Adewale Oshineye. Then there is “The Pragmatic Programmer” by Andrew Hunt and Dave Thomas (Prag Dave) and the well known “Software Craftsmanship” by Pete McBreen.

Online Resources

Active Apprenticeship Programs

Obtiva (Chicago, IL)
8th Light (Libertyville, IL)
Eden Development (Winchester, UK)

conference week

2010-02-16T21:15:00-08:00

This week will be a busy week of information overload - a week of Ruby and Rails conferences. This Thursday, the free Rails Online Conference will exclusively be about the upcoming version of Rails. Currently, it is in its beta state and will be officially available soon. I look forward to the talks and to learn more about the new features in Rails 3.

LA Ruby Conference 2010 will be on Saturday and the complementary workshops will be held on Friday. I signed up for both Ruby Koans and Intro to Ruby on Rails workshops which I’m both pretty excited about. Jim Weirich and Joe O’Brien will give the Ruby Koans workshop, and Alf Mikula (LA Ruby meetup organizer) will give the Intro to Ruby on Rails workshop.

Here are the talks I’m particularly interested in:

I look forward to meeting more Rubyists.

how to run jekyll's pygmentize on windows

2010-02-14T14:00:00-08:00

Updated 06/14/2010 – This is a quick patch created by Jon at RubyInstaller Google Group.

What You Need

Any RubyInstaller MinGW version or 1.8.7/1.9.1 mswin32 (Not tested using One-Click Installer)
jekyll gem
Python 2.3 or higher (I used 2.6.5)
setuptools 0.6c11 for easy_install
pygments (install with easy_install)

Installation

Installing Ruby, jekyll, and Python should be self explanatory. I installed RubyInstaller 1.8.7 to C:\Ruby187\ and Python 2.6.5 to C:\Python26\.

Modify the code in albino.rb and highlight.rb from C:\Ruby187\lib\ruby\gems\1.8\gems\jekyll-0.5.7\lib\jekyll\ using the following gists:

Be sure not to just replace the entire code, just the portions of the code. If you’re using Ruby 1.9.1 or your Ruby path is different, drill down to the corresponding path.

I created a folder called ‘Scripts’ under C:\Python26. I added C:\Python26 and C:\Python26\Scripts to the PATH environment variable.

In order to install pygments, you need to install easy_install which is included in setuptools. Download the source (setuptools-0.6c11.tar.gz) and egg (setuptools-0.6c11-py2.6.egg). Extract ez_setup.py from setuptools-0.6.c11.tar.gz to the same folder as setuptools-0.6c11-py2.6.egg. Open up a command prompt, navigate to the folder with the egg file and run:

python ez_setup.py setuptools-0.6c11-py2.6.egg

This will add easy_install.exe and other files to your C:\Python26\Scripts folder.

Now to install pygments, simply run this command:

easy_install Pygments

According to Jon, easy_install does not create a wrapper for the Pygmentize script, so creating a batch file pygmentize.bat under C:\Python26\Scripts should do the trick. Add this command to the batch file:

@python.exe %~dp0pygmentize %*

Now when running jekyll locally, you should be able to see the pygmentize highlights

update rss feed

2010-02-14T12:15:00-08:00

I’ve updated the rss feed to use FeedBurner.

Please point to the new feed : http://feeds.feedburner.com/sl4m

software testing club magazine

2010-02-08T18:30:00-08:00

I was one of the lucky ones to contribute to The Software Testing Club’s first magazine that released today for free. In it, you will find a small Twitter conversation I had with @QualityFrog as well as a Google Wave conversation I had with @Rob_Lambert and @YorkyAbroad. I look forward to future contributions to this wonderful magazine. Be sure to check out the bottom-left hand corner every other page to find humorous quotes.

rails 3 beta on windows using rubyinstaller 1.8.7 rc2

2010-02-07T19:15:00-08:00

Note: I have posted an update using Rails 3 RC and Ruby 1.9.2 here.

Yesterday, I upgraded my Vista x64 machine to Windows 7 x64, so I needed to set up my Ruby/Rails environment again. As done previously, I followed information on AkitaOnRails’ blog post, The Best Environment for Rails on Windows to install the latest msysgit, Exuberant CTags, gvim, and vimfiles, replacing the deprecated One-Click Ruby Installer with the new RubyInstaller 1.8.7 RC2 that officially came out today.

Requirements

RubyInstaller 1.8.7 RC2
DevKit 3.4.5r3-20091110
7-zip or zip program to uninstall 7z extensions
SQLite3

Installation

I chose C:\Ruby187\ as my default path and applied DevKit on top of it. Be sure to follow the instructions in INSTALL.txt in the DevKit archive. I placed sqlite3.dll in C:\Ruby187\bin.

I followed the instructions on Matt Hulse’s post, Massaging Rails 3 Beta on Windows to install the important gems for rails and created a quick rails 3 app.

C:\Users\skim>gem install tzinfo builder memcache-client rack rack-test rack-mount erubis mail text-format thor bundler i18n rake --no-ri --no-rdoc
Successfully installed tzinfo-0.3.16
Successfully installed builder-2.1.2
Successfully installed memcache-client-1.7.8
Successfully installed rack-1.1.0
Successfully installed rack-test-0.5.3
Successfully installed rack-mount-0.4.5
Successfully installed abstract-1.0.0
Successfully installed erubis-2.6.5
Successfully installed activesupport-2.3.5
Successfully installed mime-types-1.16
Successfully installed mail-2.1.2
Successfully installed text-hyphen-1.0.0
Successfully installed text-format-1.0.0
Successfully installed thor-0.13.0
Due to a rubygems bug, you must uninstall all older versions of bundler for 0.9 to work
Successfully installed bundler-0.9.3
Successfully installed i18n-0.3.3
Successfully installed rake-0.8.7
17 gems installed  

C:\Users\skim>gem install rails --pre --no-ri --no-rdoc
Successfully installed activesupport-3.0.0.beta
Successfully installed activemodel-3.0.0.beta
Successfully installed actionpack-3.0.0.beta
Successfully installed arel-0.2.pre
Successfully installed activerecord-3.0.0.beta
Successfully installed activeresource-3.0.0.beta
Successfully installed actionmailer-3.0.0.beta
Successfully installed railties-3.0.0.beta
Successfully installed rails-3.0.0.beta
9 gems installed

I recommend visiting RubyInstaller Google Group if you have any problems with the RubyInstaller.

jekyll and github

2010-02-04T23:30:00-08:00

I finally got jekyll and github working together thanks to Chris Parson’s github pages. I might throw this on codaset after I’m more familiar with jekyll, but in the meantime, this will do. Now I need to figure out how to link this to my domain…