From: Luis Lavena <luislavena@...>
Date: 2008-11-16T00:16:53+09:00
Subject: Re: Ruby equivalent for Lua first-class functions?

On Nov 15, 12:12 pm, Dolazy <francis.ramme...@gmail.com> wrote:
> I think one of Lua's nice features is that all functions are first-
> class functions. That makes it possible to override behavior like
> this:
>
> -- Sample stolen from Wikipedia
> local oldprint = print           -- Store current print function as
> oldprint
> print = function(s)              -- Redefine print function
>   if s == "foo" then
>     oldprint("bar")
>   else
>     oldprint(s)
>   end
> end
>
> How would you write the above sample using Ruby?
>
> Grtz,
> Francis

module Kernel
  alias_method :old_print, :print
  def my_print(*args)
    old_print "bar"
  end
  alias_method :print, :my_print
end

irb(main):017:0> print "hey"
bar
=> nil

There are several approaches to achieve the same, that's the beauty or
the curse of Ruby :-)

As more complex example, you can check how rubygems replace 'require'
functionality to be able to pick code outside the default $LOAD_PATH.

HTH,
--
Luis Lavena