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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 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

Alias for Method#super_method.

#to_s

Alias for Method#inspect.