From: Robert Klemme <bob.news@...>
Date: 2003-04-04T23:39:55+09:00
Subject: Re: To inherit or to include? That is the question.


"Jim Freeze" <jim@freeze.org> schrieb im Newsbeitrag
news:20030404085816.A61099@freeze.org...
> For example:
>
>   class AppMaker
>     def main; <stuff>; end
>   end
>   class MyApp < AppMaker
>   end
>   MyApp.new.main
>
> or
>
>   module AppMaker
>     def main; <stuff>; end
>   end
>   class MyApp
>     include AppMaker
>   end
>   MyApp.new.main
>
> I cannot see that the two behave that differently.
> I'm sure there are some differences. Maybe someone
> can help me enumerate them.

Currently I can't see why you want to inherit a main function - if it's
what I guess, then main is very application specific and does not lend
itself easily for inheritance at all.

> Ideally, I would like some set of guidelines to help
> me make a choice between these two.
>
> Right now, it's fuzzy to me which one I should use.

The simples rule is that you have to use inheritance if you want to reuse
state.  Modules can only provide methods.  So, if you have a set of
related methods that can be expected to be used in different classes, put
them together in a module.

You should have a look at the std modules. I think this can give you a
feeling how modules are done.

Regards

    robert