From: matz@... (Yukihiro Matsumoto)
Date: 2000-09-12T14:27:22+09:00
Subject: [ruby-talk:4888] Re: Re-binding a block

Hi,

In message "[ruby-talk:4887] Re: Re-binding a block"
    on 00/09/12, Dave Thomas <Dave@thomases.com> writes:

|Now, say I wanted to make it more complicated and pass parameters in
|to the block. Would it be reasonable to change instance_eval so that
|if block_given? was true, any parameters given to instance_eval were
|passed to the block? Or am I missing (yet another) clever trick?

I don't think it's good idea to change instance_eval.  How about this
yet another trick (using yet undocumented unbound method).

     class Matz2
       def internal(a)
	 puts @name
       end
       @@block = self.instance_method(:internal)
       @name = "class level"
       def initialize
         @name = "instance level"
       end

       def block
	 @@block.bind(self).call(42)
       end
     end

     Matz2.new.block

I'm amazing myself how many tricks Ruby provide.  It's far beyond the
author expected.

							matz.