Module: SingleForwardable (Ruby 2.2.2)
Description: Module : SingleForwardable - Ruby 2.2.2

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Support for the Ruby 2.2 series has ended. See here for reference.

### Home Classes Methods

### In Files

- forwardable.rb

### Methods

- #def_delegator
- #def_delegators
- #def_single_delegator
- #def_single_delegators
- #delegate
- #single_delegate

### Class/Module Index

Quicksearch

- Forwardable
- SingleForwardable

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# 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(accessor, method, ali = method) click to toggle source
Alias for: def_single_delegator
def_delegators(accessor, *methods) click to toggle source
Alias for: def_single_delegators
def_single_delegator(accessor, method, new_name=method) click to toggle source

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.

                   # File forwardable.rb, line 271
    def def_single_delegator(accessor, method, ali = method)
      str = %{
        def #{ali}(*args, &block)
          begin
            #{accessor}.__send__(:#{method}, *args, &block)
          rescue Exception
            $@.delete_if{|s| Forwardable::FILE_REGEXP =~ s} unless Forwardable::debug
            ::Kernel::raise
          end
        end
      }

      instance_eval(str, __FILE__, __LINE__)
    end

Also aliased as: def_delegator
def_single_delegators(accessor, *methods) click to toggle source

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

                   # File forwardable.rb, line 257
    def def_single_delegators(accessor, *methods)
      methods.delete("__send__")
      methods.delete("__id__")
      for method in methods
        def_single_delegator(accessor, method)
      end
    end

Also aliased as: def_delegators
delegate(hash) click to toggle source
Alias for: single_delegate
delegate method => accessor click to toggle source
delegate [method, method, ...] => accessor

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.

                   # File forwardable.rb, line 237
    def single_delegate(hash)
      hash.each{ |methods, accessor|
        methods = [methods] unless methods.respond_to?(:each)
        methods.each{ |method|
          def_single_delegator(accessor, method)
        }
      }
    end

Also aliased as: delegate