Spring is a Rails application preloader. When debugging e.g. the rails gem, you'll be wondering why your raise, puts or debugger debugging statements have no effect. That's because Spring preloads and caches your application once and all consecutive calls to it will not see any changes in your debugged gem.

Howto

Disable spring with export DISABLE_SPRING=1 in your terminal. That will keep Spring at bay in that terminal session.

In Ruby, [you can only write environment variables that subproc...

General

Programatically invoke Rails generators

Require the generator, instantiate it and invoke it (because generators are Thor::Groups, you need to invoke them with invoke_all). Example:

 require 'generators/wheelie/haml/haml_generator'
 Generators::HamlGenerator.new('argument').invoke_all

Other ways: Rails invokes its generators with Rails::Generators.invoke ARGV.shift, ARGV. From inside a Rails generator, you may call the [inherited Thor method invoke(args=[], options={}, config={})](https://github...

docopt helps you define interface for your command-line app, and automatically generate parser for it.

docopt is based on conventions that are used for decades in help messages and man pages for program interface description. Interface description in docopt is such a help message, but formalized. Here is an example:

Naval Fate.

Usage:
  naval_fate ship new <name>...
  naval_fate ship <name> move <x> <y> [--speed=<kn>]
  naval_fate ship shoot <x> <y>
  naval_fate mine (set|remove) <x> <y> [--moored|--drifting]
  naval_fate -h |...

Rubygems can produce lots of deprecation warnings, but sometimes, you cannot fix them. To have a tidy terminal with output that matters, add this to the top of your Gemfile and enjoy silence:

Deprecate.skip = true if defined?(Deprecate.skip)
Gem::Deprecate.skip = true if defined?(Gem::Deprecate.skip)

# all gems go here ...

(Inspiration)

If you want to label things with a color but don't actually care which cholor, you can use the attached Colorizer class.

To get a completely random color (some of which will clash with your design):

Colorizer.colorize(some_object) # => "#bb4faa"

To get similiar colors (e. g. bright, pale colors of different hues):

 # random hue, saturation of 0.5, lightness of 0.6
Colorizer.colorize_similarly(some_object, 0.5, 0.6) # => "#bbaaaa"

Also see the color gem.

better_errors is an awesome gem for enhanced error pages in development, featuring a live-REPL for some light debugging.

To debug the exception you got on an AJAX-Request, visit /__better_errors on your app's root path (e.g. http://localhost:3000/__better_errors). It shows the error page for the last exception that occurred, even when it has been triggered by an AJAX request.

If you want to do JavaScript-style camelization, ActiveSupport's String#camelize method can actually help you out. Simply pass a :lower argument to it.

>> 'foo_bar_baz'.camelize
=> "FooBarBaz"
>> 'foo_bar_baz'.camelize(:lower)
=> "fooBarBaz"

When using TextMate2 with the cucumber bundle, it does not recognize step definitions (e.g. custom_steps.rb) as such but believes they are plain Ruby files. But there is help!

Solution

Add these lines to the bottom of your .tm_properties file (in ~/ for global settings, in any directory for per-project settings):

[ "*_steps.rb" ]
fileType = "source.ruby.rspec.cucumber.steps"

Apparently, this works for any files. Define a regex and specify custom settings. The attached article lists all available configuration options (whic...

In a nutshell:

• Splitting a long method into sub methods is easier in instances since it is in classes. Since you must not save state in a class, you need to pass around context as a long chain of parameters again and again.
• If your public API has a single entry point, you can still have a class-level method that takes care of constructing the instance etc. So it's all win.

We now have a gem that supports our form model approach.

Ruby’s model for concurrency is based on threads. It was typical approach for object oriented languages, designed in the 90s. A thread is sequence of instructions that can be scheduled and executed in the context of a process. Several threads can be running at the same time.

Ruby’s VM process allocates a memory heap, which is shared and writable by threads. If incorrectly coordinated, those threads can lead to unexpected behaviors.

Batman is an alternative Javascript MVC with a similar flavor as AngularJS, but a lot less features and geared towards Ruby on Rails.

The attached link leads to a tutorial for a small blog written with Rails / Batman.js.

I'm collecting other Batman.js resources in my bookmarks.

When you call a method on an object, Ruby looks for the implementation of that method. It looks in the following places and uses the first implementation it finds:

1. Methods from the object's singleton class (an unnamed class that only exists for that object)
2. Methods from prepended modules (Ruby 2.0+ feature)
3. Methods from the object's class
4. Methods from included modules
5. Methods from the class hierarchy (superclass and its an...

Development environment setup

Rails Composer

Basically a comprehensive Rails Template. Prepares your development environment and lets you select web server, template engine, unit and integration testing frameworks and more.

Generate an app in minutes using an application template. With all the options you want!

Code generators

Rails Bricks

A command line wizard. Once you get it running, it creates sleek applications.

RailsBricks enables you to cre...

To print a colored full-width bar on the bash, use this bash script expression:

echo -e '\033[37;44m\nHEADING\033[0m\nLorem ipsum ...'

In Ruby:

  puts "\033[37;44m\n #{text}\033[0m" # blue bar

Notes: -e turns on escape character interpretation for echo. See this card for details on bash formatting.

The line above will print:

Did you know?

rake stats # => LOC per controllers, models, helpers; code ratios, and more
rake notes # => collects TODO, FIXME and other Tags from comments and displays them
rake about # (Rails 3+) => Rails, Ruby, Rake, Rack etc. versions, used middlewares, root dir, etc.

String#indent is not a standard Ruby method. When you use it, be sure to know where this method comes from. Many Gems shamelessly define this method for internal usage, and you'll never know when it may be removed (since it's usually not part of the Gem's API).

Unless you're using Rails 4 (which brings String#indent in ActiveSupport), you'll be best of defining it yourself. This card has it for you.

Gems that define String#indent (incomplete)
----------------------------...

Wondering how a specific method on an object is exactly named? You can use Enumerable#grep to detect it in the array of methods.

@user.methods.grep /name/ # => [:name, :first_name, :last_name]

You can also call #private_methods or #public_methods. To find only relevant methods, it is suggested to subtract generic methods like this:

User.methods - Object.methods
User.methods - ActiveRecord::Base.methods

@user.methods - Object.instance_methods
@user.methods - ActiveRecord::Base.instance_methods

When you are working with Backbone models and inheritance, at some point you want to overwrite inherited methods but call the parent's implementation, too.
In JavaScript, there is no simple "super" method like in Ruby -- so here is how to do it with Backbone.

Example

BaseClass = Backbone.Model.extend({
  initialize: function(options) {
    console.log(options.baseInfo);
  }
});

MyClass = BaseClass.extend({
  initialize: function(options) {
    console.log(options.myInfo);
  }
});

ne...

Warning: Because of (unclear) rounding issues and missing decimal places (see examples below),
do NOT use this when dealing with money. Use our amount helper instead.

In Ruby, you can easily format strings using % (short for Kernel#sprintf):

'%.2f' % 1.23456 #=> 1.23
'%.2f' % 2 #=> 2.00

However, what if you only want the decimals to be shown if they matter? There is g! It will limit the total number of displayed digits, disregarding...

If you want to switch to another ruby versions, you have several options, depending on what you want: Do you want to switch temporarily, per project, or globally?
Here is a short guide.

Unlike RVM, rbenv does not offer a command like rvm use. By default, it respects your project's .ruby-version file.

If you need to change manually, you have several options:

1. rbenv shell
2. rbenv local
3. rbenv global

You probably want rbenv shell.

How to switch your Ruby version temporarily: rbenv shell

In case you only want to...

Publish/subscribe for Ruby classes. Bonus: You do not have to declare events before using them.

I had a huge MySQL dump that took forever (as in: days) to import, while I actually just wanted to have the full database structure with some data to use on my development machine.

After trying several suggestions on how to speed up slow MySQL dump imports (which did not result in any significant improvement), I chose to import just some rows per table to suffice my needs. Since editing the file was not an option, I used a short Ruby script to manage that.

Here is how:

pv huge.dump | ruby -e 'ARGF.each_line { |l| m = l.match(/^INSERT ...

There seems to be no way to use therubyracer -v '0.11.4' and libv8 -v '3.11.8.17' on OS X Mavericks.

However, running bundle update therubyracer worked for me. It installed therubyracer -v '0.12.1' and libv8 -v '3.16.14.3' and I had not side effects.

Log of my attempts to get it working

Probably you got here when bundling failed building native extensions for therubyracer.

The libv8 (3.3.10.4) should have been installed when bundling. Unfortunately it is not building correctly on Mavericks, so the libv8.a f...