Class: SimpleDelegator

Inherits:
Delegator show all
Defined in:
lib/delegate.rb

Overview

A concrete implementation of Delegator, this class provides the means to delegate all supported method calls to the object passed into the constructor and even to change the object being delegated to at a later time with __setobj__ .

Instance Method Summary collapse

Methods inherited from Delegator

#marshal_dump, #marshal_load, #method_missing, #respond_to?

Constructor Details

#initialize(obj) ⇒ SimpleDelegator

Pass in the obj you would like to delegate method calls to.



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# File 'lib/delegate.rb', line 200

def initialize(obj)
  super
  @_sd_obj = obj
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method in the class Delegator

Instance Method Details

#__getobj__ ⇒ Object

Returns the current object method calls are being delegated to.



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# File 'lib/delegate.rb', line 206

def __getobj__
  @_sd_obj
end

#__setobj__(obj) ⇒ Object

Changes the delegate object to obj.

It’s important to note that this does not cause SimpleDelegator’s methods to change. Because of this, you probably only want to change delegation to objects of the same type as the original delegate.

Here’s an example of changing the delegation object.

names = SimpleDelegator.new(%w{James Edward Gray II})
puts names[1]    # => Edward
names.__setobj__(%w{Gavin Sinclair})
puts names[1]    # => Sinclair

Raises:

  • (ArgumentError) 


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# File 'lib/delegate.rb', line 224

def __setobj__(obj)
  raise ArgumentError, "cannot delegate to self" if self.equal?(obj)
  @_sd_obj = obj
end

#clone ⇒ Object

Clone support for the object returned by __getobj__.



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# File 'lib/delegate.rb', line 230

def clone
  super
  __setobj__(__getobj__.clone)
end

#dup(obj) ⇒ Object

Duplication support for the object returned by __getobj__.



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# File 'lib/delegate.rb', line 235

def dup(obj)
  super
  __setobj__(__getobj__.dup)
end