From: Max Muermann <ruby@...>
Date: 2007-01-31T14:59:14+09:00
Subject: Re: Tricks with method as superclass

> Cool, that worked well. Now I want to keep the args and block passed
> that was passed to the method, so I tried the following, which makes
> an anonymous subclass of Foo, and Bar is a subclass of that:
>
> class Foo
>     def initialize(*args)
>         puts "Initializing Foo"
>     end
> end
>                                 => nil
>
> def Foo(*args, &block)
>     puts args.inspect
>     block.call if block
>     Class.new(Foo).instance_eval <<-END
>             def initialize
>                 # I'm going to do something with block and args here
>                 puts "Double surprise!"
>             end
>             self
>         END

This is really cool. Regarding the double surprise problem, class_eval
instead of instance_eval (and a call to super) does the trick:

Class.new(Foo).class_eval <<-END
    def initialize
      super
      # I'm going to do something with block and args here
      puts "Double surprise!"
    end
    self
  END

=> ["Hi there!"]
Surprise!
Initializing Foo
Double surprise!

--max