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Class: UnboundMethod

Relationships & Source Files
Inherits: Object
Defined in: proc.c,
proc.c

Overview

Ruby supports two forms of objectified methods. ::Class ::Method is used to represent methods that are associated with a particular object: these method objects are bound to that object. Bound method objects for an object can be created using Object#method.

Ruby also supports unbound methods; methods objects that are not associated with a particular object. These can be created either by calling Module#instance_method or by calling unbind on a bound method object. The result of both of these is an UnboundMethod object.

Unbound methods can only be called after they are bound to an object. That object must be a kind_of? the method's original class.

class Square
  def area
    @side * @side
  end
  def initialize(side)
    @side = side
  end
end

area_un = Square.instance_method(:area)

s = Square.new(12)
area = area_un.bind(s)
area.call   #=> 144

Unbound methods are a reference to the method at the time it was objectified: subsequent changes to the underlying class will not affect the unbound method.

class Test
  def test
    :original
  end
end
um = Test.instance_method(:test)
class Test
  def test
    :modified
  end
end
t = Test.new
t.test            #=> :modified
um.bind(t).call   #=> :original

Instance Method Summary

Instance Method Details

#==(other_meth) ⇒ Boolean Also known as: #eql?

Alias for Method#==.

#arity ⇒ Fixnum

Alias for Method#arity.

#bind(obj) ⇒ method

Bind umeth to obj. If Klass was the class from which umeth was obtained, obj.kind_of?(Klass) must be true.

class A
  def test
    puts "In test, class = #{self.class}"
  end
end
class B < A
end
class C < B
end

um = B.instance_method(:test)
bm = um.bind(C.new)
bm.call
bm = um.bind(B.new)
bm.call
bm = um.bind(A.new)
bm.call

produces:

In test, class = C
In test, class = B
prog.rb:16:in `bind': bind argument must be an instance of B (TypeError)
 from prog.rb:16

#clone ⇒ Method

Alias for Method#clone.

#==(other_meth) ⇒ Boolean #eql?(other_meth) ⇒ Boolean

Alias for #==.

#hash ⇒ Integer

Alias for Method#hash.

#to_s ⇒ String

Alias for Method#inspect.

#name ⇒ Symbol

Alias for Method#name.

#original_name ⇒ Symbol

Alias for Method#original_name.

#owner ⇒ class_or_module

Alias for Method#owner.

#parameters ⇒ Array

Alias for Method#parameters.

#source_location ⇒ Array, Fixnum

Alias for Method#source_location.

#super_method ⇒ Method

Alias for Method#super_method.

#to_s

Alias for Method#inspect.