From: Trans <transfire@...>
Date: 2006-08-22T14:05:06+09:00
Subject: Re: using a module at the toplevel doesn't work


Yukihiro Matsumoto wrote:
> Hi,
>
> In message "Re: using a module at the toplevel doesn't work"
>     on Tue, 22 Aug 2006 12:40:11 +0900, "Trans" <transfire@gmail.com> writes:
>
> |Well, is there anyway to turn toplevel effects on Object off? I have a
> |real scenario where it causes issues.
> |
> |  module X
> |    def self.method_missing( name, *args )
> |      if name ...
> |        if require 'foo'
> |          send( name, *args )
> |       ...
> |
> |Now if some method is defined at toplevel it can screw up my module X
> |lazy loader.
>
> Can you show me working (well, I mean non-working) example.  I am not
> sure how above example relates to toplevel effects.

Sure. I have a bunch of build scripts that can be resused in other
scripts. Typcially people will reuse then threw one-off scripts that
simple define methods at the top level. E.g. something like

  def test
    Script.test
  end

Now the Script module uses lazy loading in order to keep it fast --no
sense in loading module's you don't need:

 module Script

  extend self

  # Some tasks belong to variant scripts.

  TASK2SCRIPT = {
    :version => :revision,
    :changelog => :revision
  }

  # When a built-in task is called it's script is dynamically loaded.

  def method_missing( meth, *args, &blk )
    file = TASK2SCRIPT[meth] || meth
    begin
      require "sake/#{file}"
      if respond_to?(meth)
        send( meth, *args, &blk )
      else
        super
      end
    rescue LoadError
      super
    end
  end

 end

As you can see my particlar 'test' example will cause an infinite loop
because the toplevel definition is being added to all objects. :(

Thanks for looking at this,
T.