From: ts <decoux@...>
Date: 2004-02-27T20:32:40+09:00
Subject: Re: Callback

>>>>> "I" == Ian Macdonald <ian@caliban.org> writes:

I> Actually, I was looking forward to an answer to that question, because
I> the same thing occurred to me, namely that the whole clause could be
I> replaced by 'cb.class'.

 cb.class give the class of `cb'

 class << cb; self end give the singleton class associated with `cb'

 For example

svg% cat b.rb
#!/usr/bin/ruby
cb = []

cb.class.instance_eval { define_method("aa") { p "nice method aa for Array" }}
class << cb; self end.instance_eval do
   define_method("bb") { p "nice method bb for cb" }
end

cb.aa
cb.bb
[1].aa
[1].bb
svg% 

svg% b.rb
"nice method aa for Array"
"nice method bb for cb"
"nice method aa for Array"
./b.rb:12: undefined method `bb' for [1]:Array (NoMethodError)
svg% 



Guy Decoux