Module: SingleForwardable (Ruby 2.7.3)
Description: Module : SingleForwardable - Ruby 2.7.3

### 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

- SingleForwardable

No matching classes.

# 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. Returns the name of the method defined.

                   # File forwardable.rb, line 305
    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

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 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

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 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