module SingleForwardable - Documentation for Ruby 4.0
Description: module SingleForwardable: SingleForwardable can be used to setup delegation at the object level as well. printer = String.
Keywords: ruby,module,SingleForwardable

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# module SingleForwardable

`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.

### Public Instance Methods

def_delegator
Alias for: def_single_delegator
def_delegators (accessor, *methods)
Alias for: def_single_delegators
def_single_delegator(accessor, method, new_name=method)
Source

    # File lib/forwardable.rb, line 305
    def def_single_delegator(accessor, method, ali = method)
      gen = Forwardable._delegator_method(self, accessor, method, ali)

      instance_eval(&gen)
    end

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.

Also aliased as: def_delegator
def_single_delegators (accessor, *methods)
Source

    # File lib/forwardable.rb, line 291
    def def_single_delegators(accessor, *methods)
      methods.each do |method|
        next if /\A__(?:send|id)__\z/ =~ method
        def_single_delegator(accessor, method)
      end
    end

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

Also aliased as: def_delegators
delegate method → accessor
delegate [method, method, ...] → accessor
Alias for: single_delegate
single_delegate
Source

    # File lib/forwardable.rb, line 270
    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

Also aliased as: delegate