Open Source

How to install rbenv and Ruby build

noreply@blogger.com (Anonymous) — Fri, 16 Mar 2018 22:31:00 +1100

rbenv use to setup different ruby environment based on your application, it's a nifty tool for development environment especially if your working different Ruby applications.

Installing instruction for rbenv

$ brew install rbenv

Add rbenv's bin path into .rc(.bash_profile) file

export PATH="$HOME/.rbenv/bin:$PATH" 
if which rbenv > /dev/null; then eval "$(rbenv init -)"; fi

Make sure you have reloaded terminal with env changes

Installing specific Ruby version Ex. 2.3.4

$ rbenv install 2.3.4

ruby-build: use openssl from homebrew
Downloading ruby-2.3.4.tar.bz2...
-> https://cache.ruby-lang.org/pub/ruby/2.4/ruby-2.3.4.tar.bz2


Installing ruby-2.3.4...


Installed ruby-2.3.4 to /Users/home/.rbenv/versions/2.3.4

Make your Ruby 2.3.4 as global

$ rbenv global 2.3.4
$ ruby -v
ruby 2.3.4p301 (2017-03-30 revision 58214) [x86_64-darwin17]

Sets the global version of Ruby to be used in all shells by writing the version name to the ~/.rbenv/version file. This version can be overridden by an application-specific .ruby-version file, or by setting the RBENV_VERSION environment variable.

Install ZSH and Oh My Zsh on your Mac

noreply@blogger.com (Anonymous) — Fri, 16 Mar 2018 21:07:00 +1100

In order to Install zsh on your mac, make sure you've installed Homebrew on your machine. Homebrew is a package manger for macOS and very handy tool to install any packages on your mac.

If you haven't installed Homebrew, have a look http://brew.sh and follow the install instructions.

Installing ZSH

$ brew install zsh

This command will install zsh on your machine

Oh My Zsh

It's a framework for managing your ZSH configuration and more than 200+ plugins. would recommend to try this.Visit http://ohmyz.sh and follow the install instructions

$ sh -c "$(curl -fsSL https://raw.github.com/robbyrussell/oh-my-zsh/master/tools/install.sh)"

You can install any kind of plugins such as github

Design Patterns - Singleton

noreply@blogger.com (Anonymous) — Mon, 26 Feb 2018 20:39:00 +1100

Singleton pattern is frequently used to provide global access point for a service. It restricts instantiation of a class to only one instance that globally available.

It's useful in your application when you need global instance which can be accessible in different parts of the application. Most common use case of this pattern is Application logging and configuration functionality.

Singleton pattern in Ruby

Class Logger
  def initialize
    @log = File.open("/tmp/tmp.log", "a")
  end

  @@instance = Logger.new

  def self.instance
    @@instance
  end

  def log(message)
    @log.puts(message)
  end

  private_method :new
end


Logger.instance.log("Log me")

In this example, we created an instance of the "Class Logger" which can be accessed by class method "Logger.instance", so when you want to log any errors/warning/notice on your app, you can simply use "log" instance method which just opened a log file and appending message on that file.

At the end of the class we made method "new" as private, so that anywhere in the application we can't create new instance of Class "Logger"

Ruby PRY

noreply@blogger.com (Anonymous) — Fri, 19 Jan 2018 22:17:00 +1100

Pry is one of the great tool for debugging ruby based application. In this blog would like to show some of the cool features of the Pry.

Ruby - Array#bsearch

noreply@blogger.com (Anonymous) — Fri, 19 Jan 2018 22:01:00 +1100

Array bsearch it's very handy and one of the fastest way to find a value from the array.

Let's do benchmark analysis, based on the result, bsearch more powerful than using array find method.

require 'benchmark'

array_data = (0..100_000_000)

Benchmark.bm do |x|
  x.report(:find) { array_data.find {|number| number > 50_000_000 } }
  x.report(:bsearch) { array_data.bsearch {|number| number > 50_000_000 } }
end

user     system      total        real
find  3.160000   0.000000   3.160000 (  3.174570)
bsearch  0.000000   0.000000   0.000000 (  0.000011)

It can find a match with only O(log n) complexity.

Node.js Best Practices - Async

noreply@blogger.com (Anonymous) — Tue, 31 Oct 2017 21:14:00 +1100

Async function allows you to write Promise based code as if it were synchronous. It was shipped with V8 Engine since the Version 7.6.

Define a function using the async keyword, then you can use the await keyword within the function's body.

async function app () {
  ...
  await ...
}

Async function is called, it returns with a Promise. When it returns a value, the promise gets fulfilled.

Async function throws an error, if it's rejected

Simple Async function

const util = require('util')
const {file} = require('fs')
const fileAsync = util.promisify(readFile)
async function app () {
  const content = await fileAsync('log')
  return content
}
app()
  .then(console.log)
  .catch(console.error)

If your applications are using Promise, then you can use "await" your Promises, instead of chaining them.

Above example leverage Promise using Node.js build-in "util.promisify" and read the file asynchronously.

Promise Reject/Error Handling

In the newer version of Node.js, if Promise gets rejected it will bubble down to the Node.js process. Make sure you handled the "try-catch" block properly on your app.

const util = require('util')
async function app () {
  try {
    await new Promise((resolve, reject) => {
      reject(new Error('error'))
    }) 
  } catch (err) {
    // handle the error
  }
}
app()
  .then(console.log)
  .catch(console.error)

Debugging Node.js application

noreply@blogger.com (Anonymous) — Tue, 24 Oct 2017 21:36:00 +1100

Debugging Node.js app is always fun, especially if you're coming from other language background such as Ruby, Python. you may looking similar debugger(binding.pry or pdb) on node js world.

In this article, let me go through how debugging node.js app with Chrome DevTool

1. Install Node.js, i use nvm

$ nvm use v8.7.0
Now using node v8.7.0 (npm v5.4.2)

2. To start debugging mode, run the Node.js app with inspect flag

node-app $ node --inspect index.js 
Debugger listening on ws://127.0.0.1:9229/a51c84e5-78c1-481e-ac5b-ab6bc78c23fe
For help see https://nodejs.org/en/docs/inspector
Debugger attached

3. Open Chrome inspector and click on "Open dedicated DevTools for Node" to debug your app code

Now you can debug your javascript code by adding breakpoint or "debugger"

Happy debugging :)

TextMate bundle for remove space, add newline, etc

noreply@blogger.com (Anonymous) — Sun, 23 Nov 2014 22:07:00 +1100

This is one of the useful bundle for TextMate which converts Tabs to Spaces, Remove Trailing Whitespace and Add a newline at end of file https://github.com/glennr/uber-glory-tmbundle

Rails 4 - Scope

noreply@blogger.com (Anonymous) — Wed, 21 Aug 2013 19:43:00 +1000

In rails 4, scopes should take a proc object or a block. Take an example this User model

Class User < ActiveRecord::Base
  attr_accessor :name,:age,:status

  def initialize(name, age)
    @name = name
    @age = age
  end
end

I would like to make default scope based on status 'user' and admin scope based on status 'admin'. In rails 3, I can make scope like this

#Rails 3
scope :admin, where(status: 'admin')
default_scope where(status: 'user')

Rails 4, I can make scope this way

#Rails 4
default_scope { where(status: 'user') } #  block
#default_scope ->{ where(status: 'admin) } #Proc valid
scope :admin, ->{ where(status: 'admin') }

If we try to use scope without(see rails3 examples) passing proc or block in Rails 4, it triggers DEPRECATION WARNING message.

Rails 4 - Finders

noreply@blogger.com (Anonymous) — Wed, 21 Aug 2013 19:19:00 +1000

Old-Style finders are deprecated
In Rails 4, Old-Style finders are deprecated. Consider User model with name, age members

Class User < ActiveRecord::Base
  attr_accessor :name,:age

  def initialize(name, age)
    @name = name
    @age = age
  end
end

In this class, If we want find user with name of 'foo'. See the difference in rails 3 and rails 4 call

#Rails 3
User.find(:all, conditions: { name: 'foo' })

#Rails 4
User.where(name: 'foo')

In rails 4, you will get DEPRECATION WARNING: Calling #find(:all) is deprecated. You can call #all directly instead or build a scope instead of using finder options.

Dynamic finders that return collections are deprecated

#Rails 3
User.find_all_by_name('foo')

#Rails 4
User.where(name: 'foo')

In Rails 4 alerts DEPRECATION WARNING if we use dynamic method(User.find_all_by_name). Preferable alternative option is User.where(...).all

Install Tombay on Mac

noreply@blogger.com (Anonymous) — Tue, 26 Mar 2013 23:43:00 +1100

Tombay is a good note-taking application for Linux.After I have changed to Mac, I was looking for a similar note-taking application. At the end, I installed Tombay on my Mac Mountain Lion/Lion.

Here are the quick steps I have followed to install Tombay.

1. Make sure you have n't installed Mono library. If your system has any previous installation, uninstall it.

2. Download and install Mono. Why we need Mono library? - Since tombay is written in C#, system needs Mono runtime to build and run on mac.

3. Get the latest source code from repository.

git clone git://git.gnome.org/tomboy

4. Build and Open the application. Go to the source code directory(tombay)

$ xbuild Tomboy-mac.sln
$ ./bundle-mac-app.sh
$ open Tomboy.app

After the above step, Tombay application is successfully installed and available on spotslight search. I hope these steps helpful to install Tombay on Mac Mountain Lion/Lion.

Install instruction for Tomcat 7 on Mac

noreply@blogger.com (Anonymous) — Mon, 18 Mar 2013 23:41:00 +1100

To install Tomcat 7 you should have Java 1.6+, so make sure version of java on your Mac by using "java --version" command.
Here are the quick steps to install Tomcat 7 on Mac. I believe it may take few minutes to install

1. Download a Core Binary file from here. The link of the binary file looks like this http://apache.techartifact.com/mirror/tomcat/tomcat-7/v7.0.37/bin/apache-tomcat-7.0.37.tar.gz
2.Extract the downloaded binary file tar -xzvf ~/Downloads/apache-tomcat-7.0.37.tar.gz
3.Create or make sure you have local folder.If you don't have it then create it sudo mkdir /usr/local Then move the extracted binary files to /usr/local sudo mv ~/Downloads/apache-tomcat-7.0.37 /usr/local
4.Soft link the installed folder to Mac's library folder. To maintain easily the installed application sudo ln -s /usr/local/apache-tomcat-7.0.37 /Library/Tomcat7
5. Change the ownership and executable permission to application folder sudo chown -R YOUR_MAC_USER_NAME /Library/Tomcat7 sudo chmod +x /Library/Tomcat7/bin/*.sh
6. Installation is done, now you can start/stop the Tomcat7 Service /Library/Tomcat7/bin/startup.sh /Library/Tomcat7/bin/shutdown.sh
7. Open your browser and type the URL to see welcome message of tomcat7 application server - http://localhost:8080

Spring Roo commands - Database setup

noreply@blogger.com (Anonymous) — Thu, 14 Mar 2013 17:14:00 +1100

Spring Roo is a next-generation rapid application development tool for Java developers. Developing domain models for application with support of Hibernate or any other provider is very easy. I was planning to explain different commands and purpose further post. This post is for simply database setup.

I believe you have setup of Spring Roo tool or STS editor which supports Spring Roo. If not please download and install it from here - http://www.springsource.org/spring-roo.

Then create a new Spring/Spring Roo project. Refer this tutorial for more information - http://static.springsource.org/spring-roo/reference/html/beginning.html

Now coming back to database setup, I generally use hibernate, so here is the command to create Hibernate provider for database PostgreSQL with username, password, database name and host name which i provide on the command. command which looks like this

roo> jpa setup --provider HIBERNATE --database POSTGRES --hostName localhost --userName user --password password --databaseName foo

If you want to change the provider, database. you can do it easily. For instance if your opted database is MySQL then change the part command like --database MYSQL

After the execution of this command, Config files and postgres artifacts for database support will be created automatically. Further post, I'll give more details about how to create a model, fields for the model and relations.

TextMate bundles/plugins - Ruby on Rails application development

noreply@blogger.com (Anonymous) — Thu, 14 Mar 2013 16:48:00 +1100

As we know the best choice of editor to develop Ruby on Rails application on Mac is TextMate. As a developer we always think application quality and easiest way of development. As we know developing rails application is fun. I think some of the TextMate plugins help developing Ruby on Rails application even more fun.

Ruby on Rails - It's one of the nice bundle for rails application development. Learn it with PeepCode - http://peepcode.com/products/textmate-for-rails-2

PeepOpen - It's a file navigation application. It helps to search a file in your project with just typing few characters of the file name.

JavaScript Tools - It contains Essential Tools for developing Javascript in TextMate

jQuery - It's a jQuery bundle for TextMate

Release - Vaadin 7.0.0!

noreply@blogger.com (Anonymous) — Wed, 6 Feb 2013 16:44:00 +1100

Vaadin team has been announced release 7.0.0. As you know vaadin is a Java Framework which has been developing modern web application and easy UI stuff on top of GWT that looks great and perform well on web application.

This release has 65 added features. You can download it from here

Check out this link for more information about the release
https://vaadin.com/blog/-/blogs/the-next-reindeer-is-here-vaadin-7-0-0-is-out

Brython - A Javascript translator

noreply@blogger.com (Anonymous) — Mon, 17 Dec 2012 23:44:00 +1100

Brython is a python to Javascript translator. Check these links for documentation and download.

Documention
Download

Handling Camera in iOS Applications

noreply@blogger.com (Anonymous) — Mon, 17 Dec 2012 23:36:00 +1100

http://blog.denivip.ru/index.php/2012/07/handling-camera-in-ios-applications/?lang=en

Hope it may helpful to implementation of handling camera in iOS Application

Rails 3.x - Undoing commands

noreply@blogger.com (Anonymous) — Wed, 21 Nov 2012 22:37:00 +1100

Controller and Action

In rails 3.x, To create a controller with actions we use this command

$ rails generate controller UserController add edit

If you want to remove the above controller and the actions

$ rails destroy controller User add edit

Model

To create a model in rails 3

$ rails generate model User name:string mobile:string

This can be undone using

$ rails destroy model User

Database migration and rollback

To migrate the state of the database using

$ rake db:migrate

We can undo a single migration by this command

$ rake db:rollback

To go all the way back to the beginning by this command

$ rake db:migrate VERSION=0

These commands may be helpful for reverting controller, model and database migration specific changes.

Clutch.IO - Library for native iOS applications

noreply@blogger.com (Anonymous) — Tue, 20 Nov 2012 20:21:00 +1100

Twitter open-sourced an easy-to-integrate library for native iOS applications which is designed to help you develop faster, deploy instantly and run A/B tests.

Git Source Repository:
https://github.com/clutchio/clutch

AWS - Windows Server 2012

noreply@blogger.com (Anonymous) — Tue, 20 Nov 2012 20:09:00 +1100

AWS Team announced available of Windows Server 2012. It comes with Free Tier, New Languages, AWS Elastic Beanstalk Support for Windows Server 2012, .NET 4.5 and Visual Studio 2012 Support, etc.

For more information and Getting Started video checkout here.

Source:
http://aws.typepad.com/aws/2012/11/windows-server-2012-now-available-on-aws.html

Rails 3.2.9

noreply@blogger.com (Anonymous) — Tue, 20 Nov 2012 20:02:00 +1100

Rails team announced it's new release 3.2.9. It includes changes/bug fixes in Action Pack, Active Model and etc.

Have a look more information here

Front/Web Engineer's tools

noreply@blogger.com (Anonymous) — Mon, 19 Nov 2012 18:32:00 +1100

Front/Web Engineers generally prefer quickly develop their application with the help of development, debug and testing tools. Check these tools. It may helpful to your web development

RequestBin - http://requestb.in/

It lets you create a URL that will collect requests made to it, then let you inspect them in a human-friendly way. Use RequestBin to see what your HTTP client is sending or to look at webhook requests.

Hurl - http://hurl.it/

It makes HTTP requests.
Enter a URL, set some headers, view the response, then share it with others.
Perfect for demoing and debugging APIs.

Feed validator - http://validator.w3.org/feed/

It's for check the syntax of Atom or RSS feeds

Link checker - http://validator.w3.org/checklink

It's extracts links recursively from a Web site and checks that no link is defined twice, that all the links are dereferenceable and warns about HTTP redirects.

Install Postgres gem issue on rails app

noreply@blogger.com (Anonymous) — Thu, 6 Sep 2012 15:08:00 +1000

When you try to install postgres gem for your application, but unfortunately you end up with this problem

$ gem install pg -v '0.14.0'
Building native extensions. This could take a while...
ERROR: Error installing pg:
    ERROR: Failed to build gem native extension.

        /home/user/.rvm/rubies/ruby-1.9.3/bin/ruby extconf.rb
checking for pg_config... yes
Using config values from /usr/bin/pg_config
You need to install postgresql-server-dev-X.Y for building a server-side extension or libpq-dev for building a client-side application.
You need to install postgresql-server-dev-X.Y for building a server-side extension or libpq-dev for building a client-side application.
checking for libpq-fe.h... *** 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=/home/user/.rvm/rubies/ruby-1.9.3/bin/ruby
    --with-pg
    --without-pg
    --with-pg-dir
    --without-pg-dir
    --with-pg-include
    --without-pg-include=${pg-dir}/include
    --with-pg-lib
    --without-pg-lib=${pg-dir}/lib
    --with-pg-config
    --without-pg-config
    --with-pg_config
    --without-pg_config

Solution:

$ sudo apt-get install libpq-dev

You need to install postgresql-server for building a server-side extension or libpq-dev for building a client-side application.

Could not find a JavaScript runtime. See https://github.com/sstephenson/execjs for a list of available runtimes. (ExecJS::RuntimeUnavailable)

noreply@blogger.com (Anonymous) — Mon, 3 Sep 2012 20:54:00 +1000

$ rails server

/home/user/.rvm/gems/ruby-1.9.3-p194/gems/execjs-1.4.0/lib/execjs/runtimes.rb:51:in `autodetect': Could not find a JavaScript runtime. See https://github.com/sstephenson/execjs for a list of available runtimes. (ExecJS::RuntimeUnavailable)

from /home/user/.rvm/gems/ruby-1.9.3-p194/gems/execjs-1.4.0/lib/execjs.rb:5:in `<module:ExecJS>'

The reason for this issue is missing Node JS Package Manager. Check this link for how to install package manger based on your operating system.

https://github.com/joyent/node/wiki/Installing-Node.js-via-package-manager

I hope it may help you to solve the problem.

The program 'rails' is currently not installed. You can install it by typing: sudo apt-get install rails

noreply@blogger.com (Anonymous) — Mon, 3 Sep 2012 17:41:00 +1000

user@localhost:~$ rails new blog
The program 'rails' is currently not installed. You can install it by typing: sudo apt-get install rails

If you get this message when you were creating new rails project. To fix this issue

1. Go to profile settings (.bashrc or .bash_profile)

2. Add this line at end of the file

[[ -s "$HOME/.rvm/scripts/rvm" ]] && source "$HOME/.rvm/scripts/rvm" # Loading RVM into a shell

3. If you are in existing shell prompt, execute this command

source ~/.bashrc
or
source ~/.bash_profile

If you open a new terminal, you can notice that rails command is automatically available.I hope this post helpful to fix rails command issue.

Note:
I believe you have installed ruby by Ruby Version Manger(RVM). Refer the installation steps
https://rvm.io/rvm/install/