From: Robert Klemme <bob.news@...>
Date: 2004-09-29T23:40:07+09:00
Subject: Re: ruby-dev summary 24298-24353


"SASADA Koichi" <ko1@atdot.net> schrieb im Newsbeitrag
news:20040929223720.2b31e9be%ko1@atdot.net...
> Hi all,
>
> This is ruby-dev summary 24298-24353.
>
>
> [ruby-dev:24302] Invoke Proc object with any method name
>
> Nowake proposed that a Proc object should be invoked with
> any method name like that:
>
> m = Proc.new( :to_s ) { 'test1' }
> p m.to_s   # => 'test1'
>
> This scheme is enabled with following code:
>
> class MethodProc < Proc
>   def initialize( *method_name, &procedure )
>     super( &procedure )
>     m = Module.new
>     method_name.each do | i |
>       m.__send__( :define_method, i, &procedure )
>     end
>     self.extend( m )
>   end
> end
>
> He made a point that it is helphul that a Proc object can
> be handled as polymorphic.
>
> Matz amazed about this idea. This issue is still open.

Just out of curiosity (and because I can't read Japanese) is there any
advantage of using a Module over using the singleton class?  As far as I
can see "self.extend(m)" creates the singleton class anyway.

Thinking a bit about this there could be numerous alternative approaches,
some of which might be more efficient.  My suggestion would be this:

module Kernel
private
  def MethodProc(*method_names, &b)
    raise ArgumentError, "No block given" unless b

    class <<b; self end.class_eval do
      method_names.each {|m| alias_method m.to_sym, :call }
    end

    b
  end
end


Kind regards

    robert