From: Phrogz <phrogz@...>
Date: 2007-11-09T05:20:03+09:00
Subject: Re: standard, pretty, and flexible meta-methods?

On Nov 8, 12:57 pm, Greg Weeks <gregwe...@shaw.ca> wrote:
> Is there a way to make meta-methods like "def_foo" available in class
> definitions without using inheritance?  Is there a standard way?  Is it
> pretty?  (Or is it perhaps pointless?)

In addition to using modules to mix in methods to only specific
classes, I should point out that you can define methods in the Module
class to have them available to every class and module you create. (Or
you can define them in the Class class to have them available only to
classes but not modules.)

class Module
  def make_method( name )
    define_method( name ){
      "Hello from #{name}"
    }
  end
end

class Foo; end

Foo.make_method( 'jimmy' )
p Foo.new.jimmy
#=> "Hello from jimmy"

module Whee; end
class Foo
  include Whee
end
Whee.make_method( 'junk' )

p Foo.new.junk
#=> "Hello from junk"

class Class
  def classes_only!
    "Classes are awesome. Modules suck!"
  end
end

p Foo.classes_only!
#=> "Classes are awesome. Modules suck!"

p Whee.classes_only!
#=> undefined method `classes_only!' for Whee:Module (NoMethodError)