This post originated from an RSS feed registered with Ruby Buzz by Jay Fields. Original Post: Ruby: Class Methods Feed Title: Jay Fields Thoughts Feed URL: http://feeds.feedburner.com/jayfields/mjKQ Feed Description: Blog about Ruby, Agile, Testing and other topics related to software development. Latest Ruby Buzz Posts Latest Ruby Buzz Posts by Jay Fields Latest Posts From Jay Fields Thoughts

1. Static methods cannot participate in an Interface. Ruby: No interfaces, thus irrelevant.
2. Static methods cannot be abstract. Ruby: No concept of abstract, also irrelevant.
3. Static methods are not polymorphic. Ruby: doesn't seem like it applies since you don't declare type in Ruby. Also, you don't access class methods directly from an instance.
4. Static methods are hard to test. Ruby: Class methods are as easy to test and mock as any instance method. Perhaps this is because they are simply instance methods of the sington class.

class String
  # an example class method
  def self.delete(string, characters)
    ...
  end

  # a better instance method
  def delete(characters)
    ...
  end
end

class Parser
  def self.process(script)
    # ...
  end
end

Parser.singleton_methods.inspect #=> ["process"]

class Parser
  def self.process(script)
    # ...
  end
  
  def self.singleton
    class << self; self; end
  end
end

Parser.singleton.instance_methods(false).inspect 
  #=> ["singleton", "new", "superclass", "allocate", "process"]

class Parser
  def self.self_process(script)
    # ...
  end
  
  def Parser.parser_process(script)
    # ...
  end
  
  class << self
    def singleton_process(script)
      # ...
    end
  end
  
  def self.singleton
    class << self; self; end
  end
end

Parser.singleton.instance_methods(false).inspect
  #=> ["singleton_process", "parser_process", "new", 
       "superclass", "allocate", "singleton", "self_process"]

class Parser
  def self.process(script)
    # ...
  end
end  

class Object
  def self.singleton
    class << self; self; end
  end
end

class HtmlParser < Parser
  
end

HtmlParser.singleton_methods.inspect
  #=> ["singleton", "process"]
HtmlParser.singleton.instance_methods(false).inspect
  #=> ["singleton", "new", "superclass", "allocate", "process"]