Why Ruby Class Methods Resist Refactoring

TLDR: Ruby class variables (@@foo) are dangerous in many ways. You should avoid them at all cost. See bottom of this card for alternatives.

Class variables are shared between a class hierarchy
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In Ruby (almost) everything is an Object. While this enables a lot of powerful features, this concept might be confusing for developers who have been programming in more static languages, such as Java or C#. This card should help understanding t...

This class contains nerdcore things such as disassembling a piece of Ruby into VM calls or [enabling tail-call optimization](http://ruby-doc.org/core-2.2.0/Ruby...

In the discussion of the difference between include and extend in Ruby, there is a misconception that extend would add methods to the singleton class of a ruby object as stated in many posts on this topic. But in fact, it is added to the a...

Do you remember finding where a method is defined?

I recently learned from a senior colleague that Method objects ar...

In Ruby, the meaning of protected and private is different from other languages like Java. (They don't hide methods from inheriting classes.)

private

Private methods can only be called with implicit receiver. As soon as you specify a...

How to define and call class methods in CoffeeScript classes:

class Foo

  @classMethod: -> 
    @otherClassMethod()
  
  instanceMethod: ->
    @otherInstanceMethod()
    @constructor.classMethod()

This can happen during development when classes without automatic reloading are pointing to classes with automatic reloading. E.g. some class in lib is calling Model.static_method.

Workaround A

Stop referencing autoloaded classes fro...

Consider this class:

class Foo

  private
  
  def test
    puts "Hello"
  end
  
end

While you can say create a block to call that method (using ampersand and colon) on Ruby 1.8, ...

1.8.7 > Foo.new.tap(&:te...

All methods generated by string_attr_reader are now added to that new module instead of the class. The result is that when overriding those methods you can now call super because they’re are inherited from the new module.