From: David Walker <d0sboots@...>
Date: 2006-11-08T11:39:11+09:00
Subject: Can't bind a singleton method to a subclass?

The behavior of this snippet doesn't make sense to me:

class A
  def A.class_method
    puts "Class method worked in #{self}"
  end
end

class B < A; end

aklass = (class << A; self; end)
bklass = (class << B; self; end)

p RUBY_VERSION

A.class_method
B.class_method

p A.method(:class_method)
p B.method(:class_method)
p aklass.instance_method(:class_method)
p bklass.instance_method(:class_method)
p A.method(:class_method).unbind
p B.method(:class_method).unbind
p A.method(:class_method).unbind.bind(A)
p B.method(:class_method).unbind.bind(B)

The output (for me) is:

"1.8.4"
Class method worked in A
Class method worked in B
#<Method: A.class_method>
#<Method: B(A).class_method>
#<UnboundMethod: #<Class:A>#class_method>
#<UnboundMethod: #<Class:A>#class_method>
#<UnboundMethod: #<Class:A>#class_method>
#<UnboundMethod: #<Class:A>#class_method>
#<Method: A.class_method>
/workplace2/test.rb:24:in `bind': singleton method called for a
different object (TypeError)
	from /workplace2/test.rb:24

In my mind, the last call should succeed, instead of raising an error.
Is it just plain impossible to re-bind the method to yield a #<Method:
B(A).class_method>?

-- 
=D ave