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Module: SingleForwardable

Relationships & Source Files
Defined in: lib/forwardable.rb

Overview

SingleForwardable can be used to setup delegation at the object level as well.

printer = String.new
printer.extend SingleForwardable        # prepare object for delegation
printer.def_delegator "STDOUT", "puts"  # add delegation for STDOUT.puts()
printer.puts "Howdy!"

Also, SingleForwardable can be used to set up delegation for a Class or Module.

class Implementation
  def self.service
    puts "serviced!"
  end
end

module Facade
  extend SingleForwardable
  def_delegator :Implementation, :service
end

Facade.service #=> serviced!

If you want to use both ::Forwardable and SingleForwardable, you can use methods def_instance_delegator and def_single_delegator, etc.

Instance Method Summary

Instance Method Details

#def_delegator(accessor, method, ali = method)

Alias for #def_single_delegator.

[ GitHub ] 

  


# File 'lib/forwardable.rb', line 318



alias def_delegator def_single_delegator


  








  

    #def_delegators(accessor, *methods)  
  



  

    

Alias for #def_single_delegators.


  



  [ GitHub ]


  

  


# File 'lib/forwardable.rb', line 317



alias def_delegators def_single_delegators


  








  

    #def_single_delegator(accessor, method, new_name = method)      Also known as: #def_delegator
  



  

    

Defines a method method which delegates to accessor (i.e. it calls the method of the same name in accessor).  If new_name is provided, it is used as the name for the delegate method. Returns the name of the method defined.


  



  [ GitHub ]


  

  


# File 'lib/forwardable.rb', line 308



def def_single_delegator(accessor, method, ali = method)
  gen = Forwardable._delegator_method(self, accessor, method, ali)

  ret = instance_eval(&gen)
  singleton_class.__send__(:ruby2_keywords, ali) if RUBY_VERSION >= '2.7'
  ret
end


  








  

    #def_single_delegators(accessor, *methods)  
    Also known as: #def_delegators
  



  

    

Shortcut for defining multiple delegator methods, but with no provision for using a different name.  The following two code samples have the same effect:



def_delegators :@records, :size, :<<, :map

def_delegator :@records, :size
def_delegator :@records, :<<
def_delegator :@records, :map


  



  [ GitHub ]


  

  


# File 'lib/forwardable.rb', line 294



def def_single_delegators(accessor, *methods)
  methods.each do |method|
    next if /\A__(?:send|id)__\z/ =~ method
    def_single_delegator(accessor, method)
  end
end


  








  

    #delegate(hash)  
  



  

    

Alias for #single_delegate.


  



  [ GitHub ]


  

  


# File 'lib/forwardable.rb', line 316



alias delegate single_delegate


  








  

    

      #delegate(method)  ⇒ accessor 
      #delegate([method, method, ...]=> accessor)  
    

    Also known as: #delegate
  



  

    

Takes a hash as its argument.  The key is a symbol or an array of symbols.  These symbols correspond to method names.  The value is the accessor to which the methods will be delegated.


  





  


  [ GitHub ]


  

  


# File 'lib/forwardable.rb', line 273



def single_delegate(hash)
  hash.each do |methods, accessor|
    unless defined?(methods.each)
      def_single_delegator(accessor, methods)
    else
      methods.each {|method| def_single_delegator(accessor, method)}
    end
  end
end