From: ts <decoux@...>
Date: 2001-11-01T02:47:03+09:00
Subject: [ruby-talk:23996] Re: Strangeness with undefining methods

>>>>> "P" == Paul Brannan <pbrannan@atdesk.com> writes:

P> In what real world situation might I use undef instead of remove_method?

 One case is (probably there are others)

pigeon% cat b.rb
#!/usr/bin/ruby
class A
   def a
      puts "A#a"
   end
end

class B < A
   def a
      puts "B#a"
   end
end

class B; undef :a; end
begin
   B.new.a
rescue NameError
   p $!
end

class B; remove_method :a; end
B.new.a
pigeon% 

pigeon% b.rb
#<NameError: undefined method `a' for #<B:0x401b7a40>>
A#a
pigeon% 

P> And when I undef a method, where does the method go, since I can't call
P> it?  (I've noticed that I can still call remove_method after an undef).

 The method is still here but has no body, and ruby test this before
 calling a method


Guy Decoux