From: Dominik Bathon <dbatml@...>
Date: 2005-04-10T02:46:24+09:00
Subject: Re: [curiousity] why aren't declarations just syntactic sugar?

On Fri, 08 Apr 2005 07:24:54 +0200, Jon Raphaelson  
<jonraphaelson@gmail.com> wrote:

> Curt Sampson wrote:
> <snip>
>>  For example: explain the results of these two programs to me:
>>  ----------
>>     def do_me_harder
>>     puts "Oh yes!"
>>     end
>>      puts do_me_harder
>> ----------
>>     module Foo
>>      def do_me_harder
>>         puts "Oh yes!"
>>     end
>>      puts do_me_harder
>>     end
>> ----------
>>  cjs
>
> Both of those will produce the output
>
> Oh yes!
> nil

No, they won't ;-)

The 2nd will raise an exception:
NameError: undefined local variable or method `do_me_harder' for Foo:Module

do_me_harder is an instance method (you can only call it on an instance of  
a class including Foo):

class A
   include Foo
end

A.new.do_me_harder

But the following would work:

module Foo
   def Foo.do_me_harder
     puts "Oh yes!"
   end

   puts do_me_harder
end

In this case do_me_harder is a singleton method of module Foo.

HTH,
Dominik