TechLEAP - ruby, rails, js, react, iOS ...

Server side with React

2015-08-10T00:38:00.000+05:30

To begin using react on server side we need two things express & react, Lets setup our project :

$ npm install express react

Once this is done, next lets create two files one for our react components(component.js) and second one will be the setup file for our express server(express.js).

In component file lets create a simple component :

var React = require('react');

var Component = React.createClass({
 render: function() {
  return React.createElement('h1', null, this.props.msg);
 }
});

module.exports = Component;

This component does nothing much simply returns h1 tag, has no props and its inner html is this.props.msg.

Next, in our express.js file lets require express, react and our component :

var express = require('express');
var React = require('react');
var Component = React.createFactory(require('./component'));

If you notice our component is wrapped in a React.createFactory() which will turn our component into a function where we can pass our props :)
Next, we will instantiate our express and add some routes and its corresponding function :

var app = express();

function main(request,response) {
 var msg = request.params.msg || 'Hellooo';
 var comp = Component({msg:msg});
 response.send(comp);
}

app.get('',main);
app.get('/:msg',main);

Finally we will set it up to listen on port 4000 :

app.listen(4000)

Before explaing what is happening in home function lets fire up our terminal and run our application:

$ nodemon express.js

You will get following result on your browser :

What we got here is a json representation of our component. To get our component rendered properly is by modifying our code by passing the component to React.renderToString :

function main(request,response) {
 var msg = request.params.msg || 'Hi from server';
 var comp = Component({msg:msg});
 response.send(React.renderToString(comp))
}

Lets try out now :

Lets pass a message parameter too http://localhost:4000/YooHoo :

Also, if you look at your developer tools you will find all react data attributes assigned to this element:

You can find this code at github : https://github.com/akshatpaul/react-examples/tree/master/react-server-side

WebView with React-Native

2015-07-28T23:12:00.001+05:30

In this post we will create a shell for loading any url in WebView with React-Native. Lets begin with generating the application structure :

$ react-native init WebviewShell

This will generate all necessary files for a iOS application. You can test this by building this application via Xcode.

Next, open up file index.ios.js and replace its code with following the following one :

'use strict';

var React = require('react-native');
var {
  AppRegistry,
  StyleSheet,
  Text,
  View,
  WebView
} = React;

var WebviewShell = React.createClass({
  render: function() {
    return (
      <View style={styles.container}>
        <WebView url={'https://www.facebook.com/'} />
      </View>
    );
  }
});

var styles = StyleSheet.create({
  container: {
    flex: 1
  }
});

AppRegistry.registerComponent('WebviewShell', () => WebviewShell);

Let us see what we have done here. We have created a component WebviewShell which returns a View. This view returns a WebView which loads our desired url :

var WebviewShell = React.createClass({
  render: function() {
    return (
      <View style={styles.container}>
        <WebView url={'https://www.facebook.com/'} />
      </View>
    );
  }
});

When we build our project in xcode it looks something like this :

Source code for this project is available at https://github.com/akshatpaul/react-examples/tree/master/WebviewShell

Exhaustive documentation on this topic is available at React-native docs https://facebook.github.io/react-native/docs/webview.html#content

JSX with Reactjs

2015-06-16T18:23:00.000+05:30

Working with react does not require you to use JSX however JSX does make life simpler. Its xml like syntax helps defining tree structure with attributes easily.

XML has some benefits like balances open and closed tags. This makes large tree easier to read than function calls or object literals.

Let us look at a simple example first without JSX to see how things get simplified as we gradually include JSX.

<!DOCTYPE HTML>
<html lang='en'>
 <head>
  <meta charset="UTF-8">
  <title>Hello World</title>
  <script src="../react.js"></script>
     <script src="../JSXTransformer.js"></script>
 </head>
 <body>
  
 <script >

  var Appo = React.createClass({
   render:function(){
    return React.createElement("h1",null, "Hello Dear") 
   }
  });

  React.render(React.createElement(Appo), document.body);
 </script>
 
 </body>
</html>

Here, in this example we are using using React.createElement. In line #15 we pass a string representing html tag, second is our property and third is the child which is inner html in this case.

Next when we want to render our component in React.render we pass Appo component and target where it has to be loaded as document.body. The output will be something like this ->

Next, lets look at one more method however its is deprecated and no longer used. React ecosystem is developing so fast that already things are getting deprecated, however having a look at the past shows how far we have come in making things easier in such a short period of time.

<!DOCTYPE HTML>
<html lang='en'>
 <head>
  <meta charset="UTF-8">
  <title>Hello World</title>
  <script src="build/react.js"></script>
     <script src="build/JSXTransformer.js"></script>
 </head>
 <body>

 <script>
  var Appo = React.createClass({
   render:function(){
    return React.DOM.h1(null, "Hello Past") 
   }
  });

  React.render(Appo(), document.body);
 </script>
 </body>
</html>

In this example we use React.DOM (line #14) pattern where we specify the tag to be used in this case h1, and first parameter is the property and second is a string which will be used as our inner html. While rendering with React.render we pass our component function and target where to be loaded in this case document body. If we have latest react you will get following error in your console ->

This also remind us to use JSX.
Let us now see how the same example looks when using JSX.

<!DOCTYPE HTML>
<html lang='en'>
 <head>
  <meta charset="UTF-8">
  <title>Hello World</title>
  <script src="build/react.js"></script>
     <script src="build/JSXTransformer.js"></script>
 </head>
 <body>
  <!-- with JSX -->
   <script type="text/jsx">
   var App = React.createClass({
    render:function(){
     return <h1>Hi from JSX</h1>
    }
   });

   React.render(<App />, document.body);
   </script>
 </body>
</html>

Here, we include type as JSX which is jsx transformer the inbrowser transformer. We have our component App having h1 tags. Next we render the it using React.render passing our component in JSX syntax and second argument as target document.body - Thats It ->

Although JSX is not required explicitly with react but it is preferred, it lets you create JavaScript objects using HTML syntax. Components serves two purpose templates and display logic. Therefore, markup and code are tied intimately together, display logic often is quite complex and to express it using template languages does become difficult. Best way to solve this problem is generating HTML and components from JavaScript code itself. JSX helps in solving all these problems with its HTML type syntax to create React tree nodes.

React.js its different - Introduction to React.js

2015-06-14T21:17:00.000+05:30

React.js –

It’s different !

What is react?

React js is a lightweight front end JavaScript library that is used for creating user interfaces. Sometimes referred as V in the MVC (which is a self-admission on React official documentation). React is very unique one of its vital feature is that it can be rendered on server side too, and both client-server can work together interoperable.

Some other facts about React - it was created by Facebook R&D, first released in 2013. It is used at Facebook in production, and Instagram.com is completely written in React.

Why we need something like react?

We have long way from traditions request-response model of web development. With ajaxification of apps user can’t wait for the request to go respond back and page to reload. And advent of single page apps became faster but at the same time complex. We can no longer re-render a page when a request occurs. Managing the state itself became difficult. These problems are something devs face everyday and React is the facebook/instagram team way of solving them. React philosophy greatly differs from usual frameworks. In this article we will explore how react is changing tradition way of thinking by understanding its key concepts which are disrupting conventional way of building front-end apps.

Key Concepts

Virtual DOM

Virtual DOM is a brand new concept, which abstracts away the DOM from you. Not so clear, let us go a bit deep on this feature. The problem responsible for creation of React was to render a section of the view as quickly as possible and Virtual DOM plays the significant role in helping achieveing this how? As the state changes Virtual DOM selectively renders sub-trees of nodes based upon this state change. This leads to least amount of DOM manipulation possible in order to keep your components aware of latest changes. In short react uses a fake DOM.

Lets take an example of a car which is our object, and has all features what a car must have, what Virtual dom does is it simply copies this cars current state (makes its replica). Now if we take this car object and make some changes like adding a gps system, changing its color, or a new cowboy style bumper. In react world when these changes are made two things happen - One, react runs a algorithm which recognizes that these changes have been made and what are the differences. Two, it updates the Dom with these differences. In other word it does not build the car again from ground up rather only make the required changes of color, gps and new bumper.

Before we move to next key concept let’s first install react to understand the examples more clearly.

Installation

The easiest way to start working with React is using JSFiddle examples :

React JSfiddle with JSX (we will learn about JSX shortly) -> https://jsfiddle.net/reactjs/69z2wepo/

React JSfiddle > https://jsfiddle.net/reactjs/5vjqabv3/

Other way is to download complete starter kit to even work offline

http://facebook.github.io/react/downloads/react-0.13.3.zip

You may also install react-tools this required npm :

npm install -g react-tools

Another usefull instrument to boost your productivity with React is React developer tools. Which is a very useful chrome extension that allows you to inspect React component hierarchy in chrome browser.

https://chrome.google.com/webstore/detail/react-developer-tools/fmkadmapgofadopljbjfkapdkoienihi

Before we dwelve into next section its time for “Hello World” program. Lets create a ‘helloworld.html’

<!DOCTYPE html>
<html>
  <head>
    <script src="build/react.js"></script>
    <script src="build/JSXTransformer.js"></script>
  </head>
  <body>
    <div id="intro"></div>
    <script type="text/jsx">
      React.render(
        <h1>Hello, world </h1>,
        document.getElementById(intro)
      );
    </script>
  </body>
</html>

If you have download reactjs version from github you will find react.js & JSXTransformer.js in build folder. Else, you can simple refer to following urls

react.js : http://fb.me/react-0.13.3.js

JSXtransformer : http://fb.me/JSXTransformer-0.13.3.js

That was simple nothing much to explain except the keyword ‘React’ which is the entry point in to react library. Also, this react code can live in a separate file and can be referenced in the html. Lets create a separate file ‘src/helloworld.js’

      React.render(
        <h1>Hello, world </h1>,
        document.getElementById(intro)
      );

And reference in our ‘helloworld.html.’

1	<script type="text/jsx" src="src/helloworld.js"></script>

You can use simple python server to run your Hello World example
($ python -m SimpleHTTPServer)

Now that we are all setup let us looks at some other concepts of react.

JSX

JSX stands for JavaScript XML syntax transform and what does it do it lets you write HTMLtype tags in your JavaScript. In other words React uses a specified version of JavaScript called jsx. Whose basic notion is to provide intuitive syntactic sugar, which represents react internal version of the DOM and is used by react components (which are the building blocks of a react app). You are fundamentally just writing XML object representations.

We must note that JSX should eventually be converted into regular JavaScript. This can be done in few ways first one is include JSXTransformer.js in your project. Other way is to precompile JSX code beforehand. This we can do using command like tools. If we have already installed react-tools using npm as mentioned in last section simply run following command :

jsx --watch src/ build/

Components

In a react project components are the building blocks of your application. Components are modular, independent, dynamic representations of HTML in your application. Most of the times Components are children of other react Components.

Let us understand this with an example:

/** @jsx React.DOM */
var car = React.createClass({
  render: function() {
    return (
      <p>{this.props.name}</p>
    );
  }
});

var Carlist = React.createClass({
  render: function() {
    return (
      <h1>My Cars:</h1>,
      <car name="Mercedes />
    );
  }
});

React.renderComponent(
  <Carlist />,
  document.querySelector('body')
)

As you see in this example there is a renderComponent what this does is it kicks off the application by rendering a component into the DOM node. You must be wondering what is this syntax I am looking at is it HTML nope its JSX (which we had discussed in our last section), which may look like HTML but is not representing actual DOM. This is reacts syntactic sugar which help us interact with virtual dom.

So far we see react is changing the way we work in front-end application. Its very different then other popular frameworks like Angular, backbone, ember and it wont be justice to them comparing it to react – as both have difference use cases. The only difference between react and other popular frameworks is that React expects you of getting and pushing data from the server. Which makes React very easy to implement front-end solution, since it simply expects you to hand it data rest all is handled by React.

BTW Who are using it ?

To build your confidence in this technology lets look at some popular apps who are using React in their production.

Facebook

Instagram

Air bnb

Yahoo

Flipboard

And many more…

We live in an era with so many js frameworks, no month passes by that we don’t find a new js framework to test. Sometimes its hard to find which framework suits our requirements. But react seems worth spending the time, for starters you may just include it to build some component in your existing application coz its light weight it wont impact your app and gradually you may convert your complete with React components.

Further Reading

React community is evolving very quickly every other week you find something new created. You may further read about Flux (application architecture which uses React views), React-Native (for building native user interface using React), Relay (framework from Facebook that provides data-fetching functionality for React apps).

Read this article and more in June 2015 edition of HealthyCode Magazine at http://healthycodemagazine.com/

RubyMotion Cheat Sheet

2015-06-13T16:04:00.001+05:30

Objective C -> RubyMotion
This is an active post where I update references and code snippets to quickly build app using RubyMotion. So lets start . . .

Changing background color

Objective-C

1 2	[webView setOpaque:NO]; webView.backgroundColor = [UIColor clearColor];

Corresponding RubyMotion Code

1 2	self.view.setOpaque(false) self.view.backgroundColor = UIColor.clearColor

**
Loading application in Webview + making url open in safari

Objective-C

#import "WebView.h"

@implementation WebView
@synthesize webView = _webView;

-(void) viewDidLoad
{

[super viewDidLoad];

UIWebView *webview = [[UIWebView alloc] init];

webview.autoresizingMask = UIViewAutoresizingFlexibleWidth;

[self.view addSubview:webview];

self.title = @"Web View";

NSString *filePath = [[NSBundle mainBundle] pathForResource:@"WebView" ofType:@"html"];

[_webView loadHTMLString:[NSString stringWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:nil] baseURL:nil];

_webView.delegate = self;

}

-(BOOL) webView:(UIWebView *)inWeb shouldStartLoadWithRequest:(NSURLRequest *)inRequest navigationType:(UIWebViewNavigationType)inType

{

if ( inType == UIWebViewNavigationTypeLinkClicked )

{

[[UIApplication sharedApplication] openURL:[inRequest URL]];

return NO;

}

return YES;

}

@end

Corresponding RubyMotion Code

class WebViewController < UIViewController

def viewDidLoad
super
 
self.title = "Web View"

self.view = UIWebView.alloc.init

view.delegate = self
webviewContent = File.read(App.resources_path + "/WebView.html") #This requires Bubble-Wrap to be installed

self.view.loadHTMLString(aboutContent, baseURL:nil)

end

#Open UIWebView delegate links in Safari.
def webView(inWeb, shouldStartLoadWithRequest:inRequest, navigationType:inType)

if inType == UIWebViewNavigationTypeLinkClicked

UIApplication.sharedApplication.openURL(inRequest.URL)

false #don't allow the web view to load the link.

end
true #return true for local file loading.

end
  
end

**

RubyMotion webview shell

To load a application in webview you can use following shell I have created.
https://github.com/akshatpaul/rubymotion-webview-shell

This shell is used create ios application for responsive urls

You require rubymotion tool chain installed on your system to use this shell.

Steps to create ios application in web view

Step 1 (Install Dependencies)
- Inside cloned repository execute 'bundle install'
Step 2 (Add your URL)

Goto main_controller.rb inside method viewDidLoad and replace url with desired url.

  def viewDidLoad
    self.view.loadRequest NSURLRequest.requestWithURL(NSURL.URLWithString("http://www.facebook.com"))
  end

Step 3 (Test application)

execute 'rake' to test the application.

That's it !

Enjoy.

Ruby-oci8 gem install fail !

2014-10-18T21:55:00.002+05:30

Oracle & rails on a mac have a very estrange relation it gets exponentially annoying to setup a rails application with Oracle and the irritant here is the installation of Ruby-oci8 gem.

This gem is not installed straight forward like any other gem, if you have already included the same in your Gemfile and tried bundle install you may get following error.

Installing ruby-oci8 (2.1.7)

Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

/Users/akshatpaul/.rvm/rubies/ruby-2.0.0-p247/bin/ruby extconf.rb

checking for load library path...

DYLD_LIBRARY_PATH is not set.

checking for cc... ok

checking for gcc... yes

checking for LP64... yes

checking for sys/types.h... yes

checking for ruby header... ok

*** extconf.rb failed ***

Could not create Makefile due to some reason, probably lack of necessary

libraries and/or headers. Check the mkmf.log file for more details. You may

need configuration options.

Provided configuration options:

--with-opt-dir

--without-opt-dir

--with-opt-include

--without-opt-include=${opt-dir}/include

--with-opt-lib

--without-opt-lib=${opt-dir}/lib

--with-make-prog

--without-make-prog

--srcdir=.

--curdir

--ruby=/Users/akshatpaul/.rvm/rubies/ruby-2.0.0-p247/bin/ruby

--with-instant-client

--without-instant-client

/Users/akshatpaul/.rvm/gems/ruby-2.0.0-p247/gems/ruby-oci8-2.1.7/ext/oci8/oraconf.rb:891:in `get_home': RuntimeError (RuntimeError)

from /Users/akshatpaul/.rvm/gems/ruby-2.0.0-p247/gems/ruby-oci8-2.1.7/ext/oci8/oraconf.rb:707:in `initialize'

from /Users/akshatpaul/.rvm/gems/ruby-2.0.0-p247/gems/ruby-oci8-2.1.7/ext/oci8/oraconf.rb:320:in `new'

from /Users/akshatpaul/.rvm/gems/ruby-2.0.0-p247/gems/ruby-oci8-2.1.7/ext/oci8/oraconf.rb:320:in `get'

from extconf.rb:18:in `<main>'

---------------------------------------------------

Error Message:

Set the environment variable ORACLE_HOME if Oracle Full Client.

Append the path of Oracle client libraries to DYLD_LIBRARY_PATH if Oracle Instant Client.

Backtrace:

/Users/akshatpaul/.rvm/gems/ruby-2.0.0-p247/gems/ruby-oci8-2.1.7/ext/oci8/oraconf.rb:891:in `get_home'

/Users/akshatpaul/.rvm/gems/ruby-2.0.0-p247/gems/ruby-oci8-2.1.7/ext/oci8/oraconf.rb:707:in `initialize'

/Users/akshatpaul/.rvm/gems/ruby-2.0.0-p247/gems/ruby-oci8-2.1.7/ext/oci8/oraconf.rb:320:in `new'

/Users/akshatpaul/.rvm/gems/ruby-2.0.0-p247/gems/ruby-oci8-2.1.7/ext/oci8/oraconf.rb:320:in `get'

extconf.rb:18:in `<main>'

---------------------------------------------------

See:

* http://rubydoc.info/gems/ruby-oci8/file/docs/install-full-client.md for Oracle full client

* http://rubydoc.info/gems/ruby-oci8/file/docs/install-instant-client.md for Oracle instant client

* http://ruby-oci8.rubyforge.org/en/file.report-installation-issue.html to report an issue.

extconf failed, exit code 1

Gem files will remain installed in /Users/akshatpaul/.rvm/gems/ruby-2.0.0-p247/gems/ruby-oci8-2.1.7 for inspection.

Results logged to /Users/akshatpaul/.rvm/gems/ruby-2.0.0-p247/extensions/x86_64-darwin-12/2.0.0-static/ruby-oci8-2.1.7/gem_make.out

An error occurred while installing ruby-oci8 (2.1.7), and Bundler cannot continue.

Make sure that `gem install ruby-oci8 -v '2.1.7'` succeeds before bundling.

Next when you try installing the gem itself by executing gem install ruby-oci8 -v '2.1.7' or any version you will get stuck here :

gem install ruby-oci8 -v '2.1.7'

akshatpaulsmbp2:pett akshatpaul$ gem install ruby-oci8 -v '2.1.7'

Building native extensions. This could take a while...

/Users/akshatpaul/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/site_ruby/2.0.0/rubygems/ext/builder.rb:73: warning: Insecure world writable dir /usr/local in PATH, mode 040777

ERROR: Error installing ruby-oci8:

ERROR: Failed to build gem native extension.

/Users/akshatpaul/.rvm/rubies/ruby-2.0.0-p247/bin/ruby extconf.rb

checking for load library path...

DYLD_LIBRARY_PATH is not set.

checking for cc... ok

checking for gcc... yes

checking for LP64... yes

checking for sys/types.h... yes

checking for ruby header... ok

*** extconf.rb failed ***

Could not create Makefile due to some reason, probably lack of necessary

libraries and/or headers. Check the mkmf.log file for more details. You may

need configuration options.

Provided configuration options:

--with-opt-dir

--without-opt-dir

--with-opt-include

--without-opt-include=${opt-dir}/include

--with-opt-lib

--without-opt-lib=${opt-dir}/lib

--with-make-prog

--without-make-prog

--srcdir=.

--curdir

--ruby=/Users/akshatpaul/.rvm/rubies/ruby-2.0.0-p247/bin/ruby

--with-instant-client

--without-instant-client

/Users/akshatpaul/.rvm/gems/ruby-2.0.0-p247/gems/ruby-oci8-2.1.7/ext/oci8/oraconf.rb:891:in `get_home': RuntimeError (RuntimeError)

from /Users/akshatpaul/.rvm/gems/ruby-2.0.0-p247/gems/ruby-oci8-2.1.7/ext/oci8/oraconf.rb:707:in `initialize'

from /Users/akshatpaul/.rvm/gems/ruby-2.0.0-p247/gems/ruby-oci8-2.1.7/ext/oci8/oraconf.rb:320:in `new'

from /Users/akshatpaul/.rvm/gems/ruby-2.0.0-p247/gems/ruby-oci8-2.1.7/ext/oci8/oraconf.rb:320:in `get'

from extconf.rb:18:in `<main>'

---------------------------------------------------

Error Message:

Set the environment variable ORACLE_HOME if Oracle Full Client.

Append the path of Oracle client libraries to DYLD_LIBRARY_PATH if Oracle Instant Client.

Backtrace:

/Users/akshatpaul/.rvm/gems/ruby-2.0.0-p247/gems/ruby-oci8-2.1.7/ext/oci8/oraconf.rb:891:in `get_home'

/Users/akshatpaul/.rvm/gems/ruby-2.0.0-p247/gems/ruby-oci8-2.1.7/ext/oci8/oraconf.rb:707:in `initialize'

/Users/akshatpaul/.rvm/gems/ruby-2.0.0-p247/gems/ruby-oci8-2.1.7/ext/oci8/oraconf.rb:320:in `new'

/Users/akshatpaul/.rvm/gems/ruby-2.0.0-p247/gems/ruby-oci8-2.1.7/ext/oci8/oraconf.rb:320:in `get'

extconf.rb:18:in `<main>'

---------------------------------------------------

See:

* http://rubydoc.info/gems/ruby-oci8/file/docs/install-full-client.md for Oracle full client

* http://rubydoc.info/gems/ruby-oci8/file/docs/install-instant-client.md for Oracle instant client

* http://ruby-oci8.rubyforge.org/en/file.report-installation-issue.html to report an issue.

extconf failed, exit code 1

Gem files will remain installed in /Users/akshatpaul/.rvm/gems/ruby-2.0.0-p247/gems/ruby-oci8-2.1.7 for inspection.

Results logged to /Users/akshatpaul/.rvm/gems/ruby-2.0.0-p247/extensions/x86_64-darwin-12/2.0.0-static/ruby-oci8-2.1.7/gem_make.out

No problem, now lets install ruby-oci8 the right way ;)

Simply follow following steps in order and you will be done :

Step 1

Go to oracle web site for some downloads http://www.oracle.com/technetwork/topics/intel-macsoft-096467.html.

Step 2

Download the 64bit versions of instantclient-sqlplus, instantclient-sdk, instantclient-basic - the 32bit versions do not work with OSX 10.92.

Note : Please download 64bit version only as 32bit just wont work on your OS 10.8+ version. Also you would require oracle login credentials to download this free stuff.

Step 3

Create directories at /opt/oracle incase its not yet created with following command:

$ mkdir /opt/oracle

Step 4

Unzip instantclient-basic, move to /opt/oracle the unzipped folder will be something like instantclient_11_2.

Note : we will be moving other two unzipped folders in this folder, wont keep them separately.

Step 5

Next unzip instantclient-sqlplus move its filed & folders to /opt/oracle/instantclient_11_2/

Step 6

Next unzip instantclient-sdk move its contents /opt/oracle/instantclient_11_2/

Step 7

Next, via terminal we will add some env variable. First, DYLD_LIBRARY_PATH=/opt/oracle/instantclient_11_2 export DYLD_LIBRARY_PATH

Secondly, ORACLE_HOME=/opt/oracle/instantclient_11_2 export ORACLE_HOME

Check if env variables are created properly by executing $ env

Step 8

Now we will create a sym link. Go to instantclient_11_2/ by executing cd /opt/oracle/instantclient_11_2.

run $ ln -s libclntsh.dylib.11.1 libclntsh.dylib

Step 9

Now run gem install ruby-oci8

Hello Swift

2014-08-02T16:11:00.000+05:30

I had written this post for HealthyCode Magazine, India - Aug 2014 edition.

Swift is the new programming language by Apple launch this year for developing apps for both iOS & OS X, combining featured from C & Objective-C. But Swift is a bit different from a high-level it looks like a forest which is similar to Objective-C having traditional features like named parameter, dynamic object model and easiness to work with Objective-C cocoa frameworks. Beyond that as we begin working with Swift we learn through similar swift is as expressive & enjoyable to work with like any other modern scripting language. With features like playground developers can experiment with their code without the pain of compiling & running the apps.

Since Swift is a young language it has borrowed goodies of both scripting languages and compiled languages

As we see in the article we will realize that although Swift has not introduced any new concept, however it is a collection of nice concept from different programing language like Ruby, Phython, Java etc.

Here we will list down the top feature which Swift has borrowed from different programing languages:

Inferred data types
In programming languages like Ruby, Haskell and JavaScript, no one wants to spend all of those keystrokes specifying data types for every variable. With Swift, iOS developers can now save a few keystrokes, too.

Example:

//so here foo is inferred as integer
let foo = 12

//Here po is inferred as integer
let po = "some string"

//Here is bar referred as double
let bar = 2 + 3.4

Though Swift support inferred data type but it is type safe language. So it does type checks when compile your code and raise any mismatched types as errors. So we can catch and fix errors at compile time instead of runtime. Though constants and variables are still explicitly typed.

Though Swift support inferred data type but it is type safe language.

Tuple
Inspire by Lisp and Python, Swift also support tuples. Language like Lisp assumed that everything was a list aka tuple. Even Python has explicit syntax for matching up for the N value return from a method with N variable that will be bound to them.

In many scenarios you want a method to return two values, incase of Objective-C there are two way to do it one is to make an object with two properties for return values, or return a dictionary containing two values. With Swift there is another way called Tuples.

1	let paidAndBalance = (18.5, 1.5)

Here we have two values paid & balance coupled into one paidAndBalance. To access individual value we can do the same by index.

paidAndBalance.0
paidAndBalance.1

// 18.5
// 1.5

We can further make code readable and convenient to use with named tuples where we can name individual parameter in a tuple.

1	let paidAndBalance = (amountPaid: 18.5, balance: 1.5)

And access the individual values via names instead of index.

paidAndBalance.amountPaid
paidAndBalance.balance

//18.5
//1.5

This make life easy & code pretty.

Clean Syntax for Dictionary aka Hashes
Objective C has complicated syntax for Dictionary, inspired from dynamic language like Ruby Swify has better and easy syntax.

1
2
3

foo["po"] = "it is nice"
foo["po"] = "this is cool"
foo["po"] = nil

Optional semicolons
Few more goodies from Phython, JavaScript and Ruby, save few more keystrokes by avoiding semicolons. Semicolons are optional at the end of each line. If you want to pack multiple expressions in the same line, you'll need a semicolon, but if you put them on individual lines, you don't need to wear out your right pinkie tapping the semicolon key.

Automatic reference (akin to garbage collection)
Inspired from Java and C# which have their own garbage collection which is responsible to release memory which is no longer used, similarly Swift has its own way to do it using automatic reference counting similar to its predecessor Objective C.

Closures aka blocks or lamda
Inspire from Lisp, Ruby and JavaScript you can pack up little anonymous bits of code and pass them around like functions. Closures can capture and store references to any constants and variables from the context in which they are defined. This is known as closing over those constants and variables, hence the name “closures”. Swift handles all of the memory management of capturing for you.

Where to go from here ?
Before you begin programming with Swift on Swift you need to download the beta version of Xcode 6 from the iOS member center.

Next, you can download Swift programming language iBook from iTunes store. It is the comprehensive reference guide for learning Swift.

Another wonderful resource to further advance your skill in Swift Using Swift with Cocoa and Objective-C. This book covers design patterns and best practices to work along with Cocoa, it also helps you leverage the use of Objective-C & Swift in same project. Available at iTunes store Besides these official guides, there are numerous tutorials available on youtube & udemy. The community is on the rise and you will find discussion, blogs & help from fellow developers on every topic.

We would conclude by saying Swift is a well thought programming language by Apple, every feature added may be inspired from other popular languages but is indeed a welcoming step to expand iOS dev community. Apple has done a commendable job with Swift and ultimate goal looks to be Less BS & faster development !

Ad-Hoc distribution - Apple's Best Kept Secret (with Rhomobile)

2012-04-27T03:39:00.000+05:30

Ad-Hoc distribution is certainly something which helps you scale the testing of your iOS application with apple letting you broadcast your app for 100 unique devices. But just as everything’s very controlled in an iOS environment, ad-hoc application distribution is bureaucratically confusing- unless we go through apples 500+ pages developers manual.

In this post as my other posts there special mention for Rhomobile apps. In case you’re not creating a rhomobile/Rhodes app plz skipt those steps beginning with Rhodes.

Lets Begin

Step 1 : Before you begin, you must be registered ios developer at developer.apple.com. Also, your developer certificate, distribution certificate should be added in the keychain.

Step 2 : In your apple ios development profile at developer.apple.com make a new provisional profile in distribution and choose ad-hoc in that. Also, select all the devices on which the application will be installed (max upto 100 devices).

Step 3 : Download the same and load it in xcode.

Step 4 : For Rhodes app – You can see all the details of the profile which we will later use in your Rhodes application’s build.yml by clicking organizer in the right side of xcode.

Step 5: For Rhodes app – following details will need to be filled in build.yml. Lets take an example :

iphone:

provisionprofile: xx32xx42-Axx1-xxCx-xxxx-xQWxERxTYxxU

sdk: iphoneos5.0

codesignidentity: "iPhone Distribution: your company name"

entitlements: ""

configuration: Release

BundleIdentifier: com.companyname.appname

BundleURLScheme: app_name_type

Now let’s map what is above in these yml settings to what you see in your xcode organizer:

Provisionprofile : this is the Provisional identifier

Sdk : this is just the sdk version

Code signidentiy : add your common name from distribution certificate from keychain.

Entitlements : just leave it blank

Configuration : has to be release for ad-hoc.

Buncleidentifier : you can see this as app identifier but there is a long code before this in organizer u can ignore the long code and simply take com(which is default)[dot]distribution_name[dot]application_name

BundleURL scheme : just name your app

Step 6 : For Rhodes app - Now what lets load your Rhodes application in xcode by following two steps : http://docs.rhomobile.com/rhodes/build

$ rake switch_app

$ rake build:iphone:setup_xcode_project

This will create a xcode project in the Rhodes source code folder. Which you can see from your build.yml. Navigate to the /platform/iphone folder and open rrhorunner.xcodeproj. This will open your Rhodes application in Xcode.
for more information on ios build with rhomobile, plz check ios build section at Rhomobile Docs.

Step 7 : Create a new configuration in your Project Settings

I am not describing here how to create info.plist file which is no longer required in case of xcode4, but definetly is necessary for testflight (I’ll try to include that later in this post). Create an Ad Hoc Distribution configuration. Click on your project in the Groups & Files pane and then select your project in the column that shows your project and targets.

If you are not already on the Info screen, click the Info tab. Next click the ‘+’ button and select Duplicate “Release” Configuration.

Give the new configuration a name, preferably ad-hoc so that you remember it :P

Setup 8 : Setting up Target

Select your Target (below your Project), click on code signing identity property and select “don’t code sign”. Also select default iPhone Distribution for Ad-Hoc distribution and iPhone developer for debug, development and release.

Step 9 : Setting up archive scheme

From the drop down menu in your tool bar next to the Run and Stop button, select Edit Scheme. Select Archive in the left pane and then set the Build Configuration to your Ad Hoc Distribution and click OK.

Step 10 : Yes its almost done !

From the top menu select Product and then click archive, your application build will be created.

Step 11 : Create installable ipa and share J.

After build is created successfully, organizer will open automatically to create the IPA file, with the archive highlighted, click the Share button and then confirm the provisioning profile you want to use. If you only have the one distribution provisioning profile it should default to the correct one. Click Next and then give the IPA file a name and save it.

Step 12 : To distribute your .ipa simply attach the file and mail it. Double click the ipa file loads it into itune, sync your itune and your application is installed on your device.

And its done !!!

BarCode Scanning using Rhodes and RhoElement

2012-01-10T22:13:00.000+05:30

Motorola barcode scanning devices are now supported with Rhodes3.3 and RhoElement2.0. Install RhoElements gem or RhoStudio and start developing for Motorola Windows Mobile, Windows CE and Android(ET1).

To enable this feature add following to build.yml:

capabilities:

-motorola

extensions: ["barcode-moto"]

Barcode API :

How to get list of scanners present on the device?

Barcode.enumerate

this returns array of hashes (‘name’,‘id’).

How to enables the scanner?

barcode_callback get the same parameters as Barcode.take_barcode

Barcode.enable(url_for(:action => :barcode_callback), {:name=>name_from_enumerate})

Callback parameters?

“status” – “ok” or “cancel”

“barcode” – recognized barcode string

How to disable a currently enabled scanner?

Barcode.disable

This reverts the scanner to its default state and flushes any current decoder settings

Performing a soft trigger start?

Barcode.start

If the scan does not result in a decode it is necessary to perform a soft stop before another soft start.

Performs a soft trigger stop ?

Barcode.stop

Enabling the scanner and start scanner?

Before callback is called scanner is disabled:

Barcode.take_barcode(url_for(:action => :barcode_callback), {:name=>name_from_enumerate})

System API example: https://github.com/rhomobile/rhodes-system-api-samples/blob/master/app/BarcodeRecognizerMoto/controller.rb

source : Rhomobile.com

Host your website on Google App Engine for free

2011-11-11T01:27:00.009+05:30

There are many advantages to host your website using Google app engine, specially if the site traffic is low and if you don't want to spend a single penny to host to your website. Plus you get 1GB of storage for images, files etc etc, and 1GB of bandwidth per day. Above all your app is served through Google's own data center so the reliability is unmatched.

So, lets get started and make your first google appspot application

Step 1: Go to appengine.google.com and create a new application. If you have never used App Engine before, you might be asked to verify your mobile phone number before you can create a new app, unless you dont have a google account too (which i presume wont be a problem !)

Step 2: Give your application a name – it should be unique and may only include lowercase alphabets and digits. For this example, our app identifier is “thisismyfirstapp” or "itsthetimetodisco".

Step 3: The next two sub-steps may scare some of you but trust me, they simply require you download and run two installers in the given sequence.

3a. Download and install Python from python.org.
3b. Download and install App Engine SDK from this code.google.com.

Step 4: Download and unzip this file myfirstapp.zip – somewhere on your desktop. It contains a basic website with some HTML pages, images and CSS that we’ll try to host with Google App Engine. You can replace the HTML, CSS and Images with your application stuff. But do not modify the .yaml files, i have modified them a bit from the original google zip files, so that at beginner lever there are no problem to push the application on cloud. If you are a python expert go ahead, play and modify them.

To name your application open the file "app.yaml" in your favorite editor and change the first line "application:" this will be the name of your application hosted on appspot like "wholikestoparty.appspot.com"

Last STEP : Finally it’s time to deploy /upload our website to Google App Engine. Open the Google App Engine Launcher program from the Start Menu, choose File –> Add Existing Application and browse to the folder where you unzipped the website.

Hit the deploy button, input your Google Account credentials and within seconds, your website should become available online at abc.appspot.com where abc is your unique app identifier. Later, if you add or modify any web page, press Deploy again and your new /edited files will get uploaded to App Engine.
*****************************************************************************************
Something more : 1. The only disadvantage on a free account at app engine is that you can host max of 10 apps, but then there are no limits to number of google accounts ;)
2. You can also buy your domain name and host using google app engine for free by forwarding and masking your domain i know this can be done easily with godaddy http://bit.ly/vj6JPK

How to build iPhone application using Rhomobile on Windows

2011-10-27T22:02:00.002+05:30

Rhohub & Rhodes from rhomobile is the only solution available for iPhone & iPad application development on Windows PC's.

This quick video explains how to build an iPhone application using rhohub :

List of some useful gems :)

2011-10-24T20:09:00.006+05:30

This is an active post and it will be updated now and then when ever i come forward any interesting gem which is really awesome and helpful. Git-hub looks to me a like a gold mine for developers, and here are some of the treasures :

* Devise:

- Devise is a flexible authentication solution for Rails based on Warden.

- Is Rack based.

- Is a complete MVC solution based on Rails engines.

- Allows you to have multiple roles (or models/scopes) signed in at the same time.

- Is based on a modularity concept: use just what you really need.
- url : https://github.com/plataformatec/devise

- Rails cast tutorial : http://railscasts.com/episodes/209-introducing-devise

* SASS

- Sass makes CSS fun again. Sass is an extension of CSS3, adding nested

rules, variables, mixins, selector inheritance, and more. It's translated to

well-formatted, standard CSS using the command line tool or a web

framework plugin.

* Bootstrap
- Bootstrap is Twitter's toolkit for kickstarting CSS for websites, apps, and
more. It includes base CSS styles for typography, forms, buttons, tables,
grids, navigation, alerts, and more.

* Tabs on Rails
- TabsOnRails is a simple Rails plugin for creating tabs and navigation menus.
It provides helpers for generating navigation menus with a flexible interface.

* Watir
- Watir, pronounced water, is an open-source (BSD) family of Ruby libraries for
automating web browsers. It supports your app no matter what technology it
is developed in. They support Internet Explorer on Windows, Firefox and
Chrome on Windows, Mac and Linux and Safari on Mac.

* Radient
- Radiant is a no-fluff, open source content management system designed for
small teams. It is similar to Textpattern or MovableType, but is a general
purpose content management system (not just a blogging engine)

* Geocoder
- Geocoder is a complete geocoding solution for Ruby. God dammit its so easy to implement and your app is packed all the google maps goodness in minutes.
- url : https://github.com/alexreisner/geocoder
- Tutorial : http://railscasts.com/episodes/273-geocoder

Success factors to know if Agile is really working for your project.

2011-08-29T23:54:00.006+05:30

Some takeaways from last week's BA conference at ThoughtWorks-Pune, although not related to thorough req. analysis, but in condensed version of few amazing talks blended with my personal inputs.

A good process approach gives good results on short, medium and long terms. Measuring the trends for monitored parameters helps to check if there exists a decline in them. It is important to see that after 6 months, 1 year, or after a specific period your project does not fall into technical debt issues (“spaghetti code”). Serious technical debt problems is a sign of non-Agile process. That result from a primary Agile principle. ”Continuous attention to technical excellence and good design enhances agility.”

Some common practices and principles one must keep a check on:

Your documents should be effective: rather short, but must contain the essential information.
As derivate issue: your products should have good architectures and good design, resulted from continuous adaptation.
The developers should be able to sustain Agile specific activities, such as refactoring and TDD. Also an Agile developer should have design and architecture knowledge on vertical dimension and also system analysis abilities – on horizontal dimension.
You should have already a good history on responding to changing requirements and often deliveries of value encapsulating software.

I agree that many of the soft metrics like associate satisfaction, customer collaboration and improved team interaction are the core, in case of sizable teams the following metrics are ones that can be very helpful :

Speed to Market/Cycle Time (reduce)

Client reported defect trends (reduce)

Unplanned attrition (reduce to show associate satisfaction)

Customer partnership agreements (eliminate projects without a customer)

This metrics need to evolve and usually outlive their usefulness after 6-9 months as teams seek to meet the metric rather than adopt an agile mind set and continuously improve.

However, to check whether your system is Agile and is working properly try answering these simple questions honestly :

Are we continuously improving our process?

Are we delivering working, tested, valuable software every month or less?

Are we delivering what the business needs most?

If you can answer yes to those three questions then definitely, "Agile is working for you."

People who read "Success factors to know if Agile is really working for your project." also read :

"Agile efforts : A step towards cheap changes !"

Ruby Style Guide : How to write understandable & beautiful code !

2011-07-26T13:17:00.000+05:30




You may not like all rules presented here, but they work very well for

me and have helped producing high quality code.  Everyone is free to

code however they want, write and follow their own style guides, but

when you contribute to my code, please follow these rules:





== Formatting:



* Use ASCII (or UTF-8, if you have to).



* Use 2 space indent, no tabs.



* Use Unix-style line endings.



* Use spaces around operators, after commas, colons and semicolons,

  around { and before }.



* No spaces after (, [ and before ], ).



* Use two spaces before statement modifiers (postfix

  if/unless/while/until/rescue).



* Indent when as deep as case.



* Use an empty line before the return value of a method (unless it

  only has one line), and an empty line between defs.



* Use RDoc and its conventions for API documentation.  Don't put an

  empty line between the comment block and the def.



* Use empty lines to break up a long method into logical paragraphs.



* Keep lines fewer than 80 characters.



* Avoid trailing whitespace.





== Syntax:



* Use def with parentheses when there are arguments.



* Never use for, unless you exactly know why.



* Never use then.



* Use when x; ... for one-line cases.



* Use &&/|| for boolean expressions, and/or for control flow.  (Rule

  of thumb: If you have to use outer parentheses, you are using the

  wrong operators.)



* Avoid multiline ?:, use if.



* Suppress superfluous parentheses when calling methods, but keep them

  when calling "functions", i.e. when you use the return value in the

  same line.



    x = Math.sin(y)

    array.delete e



* Prefer {...} over do...end.  Multiline {...} is fine: having

  different statement endings (} for blocks, end for if/while/...)

  makes it easier to see what ends where.  But use do...end for

  "control flow" and "method definitions" (e.g. in Rakefiles and

  certain DSLs.)  Avoid do...end when chaining.



* Avoid return where not required.



* Avoid line continuation (\) where not required.



* Using the return value of = is okay:



    if v = array.grep(/foo/) ...



* Use ||= freely.



* Use non-OO regexps (they won't make the code better).  Freely use

  =~, $0-9, $~, $` and $' when needed.





== Naming:



* Use snake_case for methods.



* Use CamelCase for classes and modules.  (Keep acronyms like HTTP,

  RFC, XML uppercase.)



* Use SCREAMING_SNAKE_CASE for other constants.



* The length of an identifier determines its scope.  Use one-letter

  variables for short block/method parameters, according to this

  scheme:



    a,b,c: any object

    d: directory names

    e: elements of an Enumerable

    ex: rescued exceptions

    f: files and file names

    i,j: indexes

    k: the key part of a hash entry

    m: methods

    o: any object

    r: return values of short methods

    s: strings

    v: any value

    v: the value part of a hash entry

    x,y,z: numbers



  And in general, the first letter of the class name if all objects

  are of that type.



* Use _ or names prefixed with _ for unused variables.



* When using inject with short blocks, name the arguments |a, e|

  (mnemonic: accumulator, element)



* When defining binary operators, name the argument "other".



* Prefer map over collect, find over detect, find_all over select,

  size over length.





== Comments:



* Comments longer than a word are capitalized and use punctuation.

  Use two spaces after periods.



* Avoid superfluous comments.





== The rest:



* Write ruby -w safe code.



* Avoid hashes-as-optional-parameters.  Does the method do too much?



* Avoid long methods.



* Avoid long parameter lists.



* Use def self.method to define singleton methods.



* Add "global" methods to Kernel (if you have to) and make them private.



* Avoid alias when alias_method will do.



* Use OptionParser for parsing complex command line options and

  ruby -s for trivial command line options.



* Write for 1.8, but avoid doing things you know that will break in 1.9.



* Avoid needless metaprogramming.





== General:



* Code in a functional way, avoid mutation when it makes sense.



* Do not mutate arguments unless that is the purpose of the method.



* Do not mess around in core classes when writing libraries.



* Do not program defensively.

  (See http://www.erlang.se/doc/programming_rules.shtml#HDR11.)



* Keep the code simple.



* Don't overdesign.



* Don't underdesign.



* Avoid bugs.



* Read other style guides and apply the parts that don't dissent with

  this list.



* Be consistent.



* Use common sense.

Original Source: Chneukirchen RubyStyle guide

Rhomobile - Android error ['.' is not recognized error -running rake run:android]

2011-06-07T17:10:00.001+05:30

I see lots of posts & mails on Rhomobile Groups related to following error for Android applications :

'.' is not recognized as an internal or external command,
operable program or batch file.
Error building APK file

After upgrading your rhodes to latest version i.e. 3.0.1, the problem was solved for many (Alway remember, in every few weeks we gatta update rhodes/rhosync, as a new better/stable version gets released with all the reported bugs fixed - so keep urself updated and take a fresh download in few weeks :P)

But still in sme cases due to versions of Windows, ruby and rake gem blah blah the problem persists, in that case you have to manually modify few file (its really easy :D)

Find the file named androidcommon.rb in your <RhodesHome>platform
\android\build directory and locate the following line:
Jake.run File.join(".", "apkbuilder" + $bat_ext), params

Comment that line out and replace with
Jake.run("apkbuilder" + $bat_ext, params)

When done it should look like:
#Jake.run File.join(".", "apkbuilder" + $bat_ext), params
Jake.run("apkbuilder" + $bat_ext, params)

thanks to Brian Resler for sharing this solution :)
and daniel for sharing your problem :)

Agile efforts : A step towards cheap changes !

2011-05-31T18:27:00.001+05:30

Q.How can we make enough changes CHEAPLY ?
A. Agile engineering efforts

Agile engineering efforts is simply the easiest answer to this question. Agile practices are suppose to provide flat cost of change curve, but there are many perils involved with it, as it is not enough only to follow the practices, what is more important How do we know how EFFECTIVE we are in achieving this curve?

For starting, with these easy five questions we can :)

1-One
How long until you see feedback from a test after writing or changing a line of code?
"Speed of feedback is directly proportional to the speed at which you work"

2-Two
Commits - How many one liner changes can be commited and pushed to test in an hour or hours or in a day?

3-Three
How many people on the team can explain the details of any particular piece of code?

The more understandability of code across team the more easy it would be to make changes in future.

4-Four
What percentage of team members paired with eachother in last two days?

Pairing fellow team memebers speeds up communication and builds trust.

5-Five
How many manual steps does it takes to get a build into Production?

More the transactions, longer the cycles & bigger the batches increases overall time and cost.
With less transactions comes less cost and lower costs associated with adding new features.

Lets sum-up this CHEAP formula quickly :P
#1 - Make it cheaper to CHANGE CODE.
#2 - Make it cheaper to CHECK IN CODE.
#3 - Make it cheaper to UNDERSTAND THE CODE.
#4 - Make it cheaper for TEAMMATES TO COMMUNICATE.
#5 - Make it cheaper to PUSH TO PRODUCTION.

Maintaing this cure is simple yet very complex as it requires lot of errorts across team, but practicing with comman-sense makes it a pleasant experience for developers and a CHEAPER one for client.

People who read "Agile efforts : A step towards cheap changes !" also read :

"Success factors to know if Agile is really working for your project."

How to make your first application using Rhodes / Rhomobile ! "Hello World"

2011-04-21T16:34:00.005+05:30

After all the installations are done using Instant rhodes, one click installations to Rhodes, Rhosync, ruby, make and what not ;)
Dont have it yet download it from here : Installations

Generate rhodes application

$ rhodes app storemanager http://localhost:9292/application

This will generate an application directory called “storemanager” with several files. Note also that the third argument above is the URL to the RhoSync server data source ("required only in the case u will be using rhosync server, one can omit the URL for pure RHODES app")

After creating our application, lets generate model for our app, go to the app folder :

$ cd storemanager

Test it by building the app for your device simulator, i work on blackberry so let me rake it for BB for iphone just replace BB by iphone

$ rake run:bb
or $ rake run:iphone

U'll nother its a blank application right now, we need a model for it, so lets generate one :

$ rhodes model product brand,name,price,quantity,sku

Model name is Product and rest are various attributes it has, if you are families with ruby on rails this is similar to scaffolding, but even if you are not it does not matter.
Lets get back to what this post is all about saying "Hello World"

Edit the app/index.erb to create some content or app/index.bb.erb in case of BlackBerry, link your index page to another erb page :

<div class="toolbar">
  <h1 id="pageTitle">
    Small demo app
  </h1>
</div>

<ul id="home" selected="true" title="Hello">
  <li><a href="another.erb">Hello, world which links to another page</a></li>
</ul>

Lets test it :

$ rake run:bb
or $ rake run:iphone
u can also run the same app for your Android.

Is it done, Yes it is : Its that simple :)

Editing Blackberry application menu

2011-04-06T11:53:00.001+05:30

With CSS you can easily modify you screen layout and make powerful intutive application.

But to modify the phone menu - specifically for Black Berry & Android devices, Rhodes provide following easy API's :

@default_menu = { 
  "Item Label 1" => "/item1path", 
  "Item Label 2" => "/item2path",
   .

. 
}

@menu = { 
  "Item Label 1" => "/item1path", 
  "Item Label 2" => "/item2path", 
  .

.  
}

Default Menu

This is the BB/Android by default menu, any changes made in this api will refect across all pages of your application.

Following changes are made in application.rb placed in your rhodes applications /app folder.

Example :

class AppApplication < Rho::RhoApplication
  def initialize
    super
    @default_menu = {
      "Go Home" => :home, 
      "View Accounts" => "/app/Account", #Depending on your app specific action can be specified      "Do Refresh" => :refresh, 
      "Perform Sync" => :sync, 
      "App Options" => :options, 
      "View Log" => :log,
      :separator => nil,
      "Exit" => :close
    }
  end
end   

Clicking your BB menu button will open up following list :

Go Home
View Accounts
Do Refresh
Performance Sync
App Option
View Log         
Exit








Menu -
In case your application has specific menu for each and every page, you have use Menu api.

Following changes are made in your application controller, each menu can be tailored according to specific action. 
def index
  @accounts = Account.find(:all)
  @menu = { 
    "Go Home" => :home, 
    "Refresh" => :refresh, 
    "Options" => :options, 
    :separator => nil, 
    "Log" => :log, 
    "New Account" => "/app/Account/new" 
  }
  render
end

Following menu will be rendered on index page of your application :
Go Home
Refresh
Options    
Log
New Account









Note : Above menu is only for Index page, rest all the pages will render the Default_Menu.

Layouts, CSS, Javascript framework, Native toolbar control, native tabbar control and various other API's can be modified in Rhodes. For complete documentation check : http://docs.rhomobile.com/rhodes/ui

Reset sync server from Rhodes application

2011-04-01T00:08:00.000+05:30

Sometimes after your application is up and running, there might be need to change your sync server or the path of your rhosync server.

Changing the syncserver option requires updating the SyncEngine at runtime, Following ruby call is available for this :::

****

SyncEngine.set_syncserver(url)

****

To fetch present syncserver use ::: Rho::RhoConfig.syncserver

There are many configurations for your Rhodes application, at rhomobile docs

http://docs.rhomobile.com/rhodes/configuration :)

Creating your Rhodes app using BlackBerry signed keys

2011-03-15T13:32:00.000+05:30

One great news before you go ahead, RIM has waved off $20 for signed keys, its free now you just need to verify yourself using your credit card for $1 which will be refunded in your statement :)

To create you application that can be run/tested on your BlackBerry device you have to follow
5 steps and you're done.

Fill the BB signedkeys form.
Wait for .csi files - which u'll receive in your mailbox in maximum 48 hrs (usually you get these files same day on next morning).
Run these files generate your password .
Sig files created.
Make required changes for Rhomobile.

IMP : Please memorize any PIN or Password/Key you enter, coz u may need it later on, its better if you stick to only one, as that will be easier to remember.

Step 1 : Fill the order form at https://www.blackberry.com/SignedKeys/ its a simple form, one thing to remember is that u memorize your PIN, coz the .csi files you receive next day will require the same pin entered while you were dreaming and filling the form.

Step 2 : Next day or max in 48hrs you'll receive three files in separate mails from BlackBerry websigner, simply download each and run them, enter the same PIN as mentioned in form above, and you can set a new password for your applications. The name of these files are ***RRT***.csi, ***RCR***.csi , ***RBB***.csi , in-case you miss to execute any file, u'll receive error while building your app.

Following are the instructions you'll receive in mail :
BlackBerry JDE or BlackBerry JDE Component Package Users:
1) Double-click on the attachment.
2) If a dialog box appears that states that a private key cannot be found, complete steps 3 through 6 before you continue. Otherwise, proceed to step 7.
3) Click "Yes" to create a new key pair file.
4) Type a password for your private key of at least 8 characters, and type it again to confirm. This is your private key password, which protects your private key. Please remember this password as you will be prompted for it each time signing is attempted or a signature key is installed.
5) Click "Ok"
6) Move your mouse to generate date for a new private key.
7) In the "Registration PIN" field, type the PIN number that you supplied on the signature key order form.
8) In the Private Key password field, type the password created in step 4.
9) Click "Register".
10) Click "Exit".
11) Repeat this process for the other .csi files.

Step 4 : After successful execution of .csi files, three new files will be created in your BlackBerry JDE folder ( to be specific they'll be in this folder : C:\Program Files\Research In Motion\BlackBerry JDE 4.6.0\bin ). These are >> sigtool.db, sigtool.csk and sigtool.set.

Step 5 : This step is only for Rhomobile developers, as you remember the password entered while running .csi files, mention the same in rhobuild.yml placed in Rhodes folder in Ruby gems.
A point to remember, if you are using Instant rhodes then your rhode gem will be present in your instant rhodes folder, as rhodes uses Ruby from InstantRhodes directory.

After you're done with above steps, its time to buid cod files for your application these will be installed on your blackberry device.
Traverse to the rhodes application directory from command prompt and instead rake:run bb execute "rake device:bb:production". On success your signed-build files will be calmly sleeping in rodhes application bin\target folder, copy all the files to your BB device and run .jad file from ota-web, and your app will be installed.

BlackBerry OS supported by Rhodes : 4.6, 4.7, 5.0, 6.0.

4.2 and 4.5 are supported but database access is very slow on these devices.

Rhodes in a Nutshell : ROR, meetup-Pune [Fri, 28th Jan11]

2011-03-14T18:01:00.000+05:30

Rhodes in a nutshell : Jan, ROR MEETUP

View more presentations from akshatpaul

Heroku Create: No ssh public key found in ~/.ssh/id_[rd]sa.pub

2010-12-02T12:55:00.001+05:30

For those who are trying out Heroku for the first time, and have not set up their Mac/PC for keypair authentication, here is what you need to do in order to generate ssh public keys.

If you keep seeing this:

$ heroku create
Enter your Heroku credentials.
Email:
Password:
No ssh public key found in /Users/mike/.ssh/id_[rd]sa.pub.  You may want to specify the full path to the keyfile.

1. Generate RSA key:

$ ssh-keygen
Generating public/private rsa key pair.
Enter file in which to save the key (/Users/mike/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Your identification has been saved in /Users/mike/.ssh/id_rsa.
Your public key has been saved in /Users/mike/.ssh/id_rsa.pub.
The key fingerprint is:
The key's randomart image is:

2. Generate DSA key:

$ ssh-keygen -t dsa
Generating public/private dsa key pair.
Enter file in which to save the key (/Users/mike/.ssh/id_dsa):
Enter passphrase (empty for no passphrase):
Your identification has been saved in /Users/mike/.ssh/id_dsa.
Your public key has been saved in /Users/mike/.ssh/id_dsa.pub.
The key fingerprint is:
The key's randomart image is:

3. Create your Heroku app:

$ heroku create
Enter your Heroku credentials.
Email:
Password:
Uploading ssh public key /Users/mike/.ssh/id_rsa.pub
Created http://myapp.heroku.com/ | git@heroku.com:myapp.git
Git remote heroku added

MySQL Error: rake db:migrate (Page 1) - Setup and Configuration - Rails Forum - Ruby on Rails Help and Discussion Forum

2010-11-29T00:36:00.000+05:30

MySQL Error: rake db:migrate (Page 1) - Setup and Configuration - Rails Forum - Ruby on Rails Help and Discussion Forum

Not able to create DataBase : "MySQL and Rails3" ?

2010-11-28T01:57:00.000+05:30

Not able to create DB : MySQL and Rails3 ?

For all those who have migrated from Rails 2.3 to Rails 3 must be facing this one initial problem if you are using Mysql instead of sqlite3 which comes along with rails 3 gem.

***********************************************************************

rake db:migrate
(in C:/Documents and Settings/mpenta/My Documents/Aptana Studio/demo)
!!! The bundled mysql.rb driver has been removed from Rails 2.2. Please install the mysql gem and try again: gem install mysql.
rake aborted!
126: The specified module could not be found. – C:/ruby/lib/ruby/gems/1.8/gems/mysql-2.7.3-x86-mswin32/ext/mysql.so

(See full trace by running task with—trace)

*************************************************************************

Rails 3 is a bit different, no doubt its more powerful and structured but things are a bit different here.

So lets first check u’ve made all installations :

Ruby 1.8.7 or above

Rails gem (rails 3)

Bundler gem (now that something new)

Yes bundler is something new and interesting – as they say “Bundler is the best way to manage your application dependencies ”.

What exactly bundler do ?

Bundler manages an application's dependencies through its entire life across many machines systematically and repeatedly.

For more information on use of bundler visit : http://gembundler.com/rationale.html

Steps for new Rails 3 app :

Step 1 : rails new app (for creating new app)

Step 2 : make required changes in config/database.yml file.

Example for mysql :

# SQLite version 3.x

# gem install sqlite3-ruby (not necessary on OS X Leopard)

development:

adapter: mysql

encoding: utf8

database: temp_development

username: root

password:

socket: /tmp/mysql.sock

# Warning: The database defined as 'test' will be erased and

# re-generated from your development database when you run 'rake'.

# Do not set this db to the same as development or production.

test:

adapter: mysql

encoding: utf8

database: temp_test

username: root

password:

socket: /tmp/mysql.sock

production:

adapter: mysql

encoding: utf8

database: temp_production

username: root

password:

socket: /tmp/mysql.sock

Step 4 : Include “mysql” in gemfile

Step 5 : bundle install [appname]

A .bundle directory will be installed in you’re the root of you application.

All set to do rake db:create, and continue making your awesome rails 3 application.

Symbols are enigma !!!

2010-11-24T17:32:00.000+05:30

Symbols in ruby are an enigma. We all use them, but many don’t really understand them.

So really, what is a symbol?

In simple words, a symbol is something that you use to represent names and strings. What this boils down to is a way to efficiently have descriptive names while saving the space one would use to generate a string for each naming instance.

The Case of Dr. Jones

Dr. Jones is a Psycologist. He regularly uses word association tests to diagnose patients and uses ruby to keep track of everything. His first patient, Why, steps up to the plate:

Dr J: Red
Why : Ruby
Dr J: Transportation
Why : Rails
Dr J: Chunky
Why : Bacon

Dr Jones creates a hash to store his data:

why = {"red" => "ruby", "transportation" => "rails", "chunky" => "bacon"}

Dr. Jones’s second patient, Bob, turns in his survey results:

bob = {"red" => "paint", "transportation" => "car", "chunky" => "fat"}

The Problem

After running several hundred word association tests, Dr. Jones begins to realize that he’s running out of memory! On a hunch, Jones runs tests in irb:


> patient1 = { "ruby" => "red" }
> patient2 = { "ruby" => "programming" }
> patient1.each_key {|key| puts key.object_id.to_s}
211006
> patient2.each_key {|key| puts key.object_id.to_s}
203536

Well look at that, each time he creates a hash to store his information, ruby creates a new string object in a different memory location for each key. Fortunately, there’s an alternative.

Symbols to the Rescue

Unlike strings, symbols of the same name are initialized and exist in memory only once during a session of ruby. Symbols are most obviously useful when you’re going to be reusing strings representing something else. Reproducing Dr. Jones’s tests, we are able to see this directly:


> patient1 = { :ruby => "red" }
> patient2 = { :ruby => "programming" }
> patient1.each_key {|key| puts key.object_id.to_s}
3918094
> patient2.each_key {|key| puts key.object_id.to_s}
3918094

Using symbols, we’ve used a single memory address to represent the word ruby in our word association tests. Over time, this can save alot of space.

So I’m no shrink, when else will I want to use symbols?

Symbols are useful whenever you’re going to be reusing a word over and over to represent something else, whether its a key in a hash or the method you’re using in an http query. An example from the latest and greatest web framework Ruby on Rails is its use of symbols in routes and links. Rails defines actions within controllers to do things within the framework before rendering a web page, so a link in Rails may look like:


    link_to("View Article", :controller => "articles", :action => "show", :id => 1)

When an application may have hundreds of links, or atleast hundreds of references to different actions and controllers, it is significantly more efficient to use symbols than strings.

Finally, its important to note that the usefulness of symbols is not restricted to keys in hashes. For example, if one was writing a http client or server they might use get and post several times within their application, and it might be appropriate to use:


    do_this if query == :get

    ...
    send_message_to_server(:post,filename)

Any time a string could be used over and over, a symbol may be a good candidate for replacement.

Updates

In #ruby-lang on Freenode (irc.freenode.net) Aria and nome presented helpful additions to this article.

11:58 < Aria> Also, the entirely realistic reasoning for using symbols: If you 
              are going to refer to a method name, use a symbol. Because /by 
              defining the method/, the symbol exists anyway.

12:03 < nome> kevinclark: the intention of symbols are for identification of 
              (user-level, primarily) constructs: a slot in a hash, a method, 
              an option, etc.

Also note Aria’s response to Geoff’s question in the comments:

Geoff -
I'd be interested in knowing exactly how
much memory 1,000 strings ("red") uses over :red.

And remember, outside of Rails, "red" != :red

Aria - 
How much memory? 20 bytes per object, plus storage for the data, 3 bytes,
plus the length storage (4 byes)—so 27,000 bytes or so.

Versus one copy of the entry in the symbol table, which is likely to be just 
a few bytes (I could check, but I know for certain it’s in the tens, not tens 
of thousands of bytes range.)

I (generally) use the following rule on string vs symbols:

(1) If the contents (i.e. the sequence of characters) of the object is important, use a String.

(2) If the identity of the object is important, use a Symbol.