Rails - Nov 2006 - Plug-in question: define a module first or just open the class definition?

I notice that some plug-ins first do something like:
  module MyPlugin
    def do_something_very_funky
    end
  end

and than include this into one of Rails'' existing classes (often in the
same file).

  module ActionController
    class Base
       include MyPlugin
    end
  end

Is there any advantage to this compared to simply doing:

  module ActionController
    class Base
      def so_something_very_funky
      end
    end
  end

I can''t think of any myself.


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Read the chapter on Classes and Modules in Programming Ruby by Dave
Thomas. Then read the Rails Plugin - Extending the Rails Core
Functionality by James Adam for an indepth coverage on plugins.


On 11/28/06, bigsmoke-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
<bigsmoke-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
>
> I notice that some plug-ins first do something like:
>   module MyPlugin
>     def do_something_very_funky
>     end
>   end
>
> and than include this into one of Rails'' existing classes (often
in the
> same file).
>
>   module ActionController
>     class Base
>        include MyPlugin
>     end
>   end
>
> Is there any advantage to this compared to simply doing:
>
>   module ActionController
>     class Base
>       def so_something_very_funky
>       end
>     end
>   end
>
> I can''t think of any myself.
>
>
> >
>
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Well, I read that chapter before I started this thread :-)

On Dec 3, 6:33 am, "Bala Paranj"
<bcpar...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> Read the chapter on Classes and Modules in Programming Ruby by Dave
> Thomas. Then read the Rails Plugin - Extending the Rails Core
> Functionality by James Adam for an indepth coverage on plugins.
>
> On 11/28/06, bigsm...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
<bigsm...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>
>
>
> > I notice that some plug-ins first do something like:
> >   module MyPlugin
> >     def do_something_very_funky
> >     end
> >   end
>
> > and than include this into one of Rails'' existing classes
(often in the
> > same file).
>
> >   module ActionController
> >     class Base
> >        include MyPlugin
> >     end
> >   end
>
> > Is there any advantage to this compared to simply doing:
>
> >   module ActionController
> >     class Base
> >       def so_something_very_funky
> >       end
> >     end
> >   end
> 
> > I can''t think of any myself.

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I don''t think you can use the same name ActionController for your
module.
The main idea here is that you once you define a module with your methods in
it, you can mix-in any of the classes that you wish.

It gives you a multiple-inheritance like behaviour. It provides namespace
also.


On 12/5/06, bigsmoke-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
<bigsmoke-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
>
>
> Well, I read that chapter before I started this thread :-)
>
>

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I understand which purpose modules serve. My question, however, was if
there''s any
advantage to defining a module for no other purpose than extending a
particular class
instead of just directly changing that class. I hope I didn''t add more
confusion to my
already vague question.

On Dec 5, 8:07 pm, "Bala Paranj"
<bcpar...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> I don''t think you can use the same name ActionController for your
module.
> The main idea here is that you once you define a module with your methods
in
> it, you can mix-in any of the classes that you wish.
>
> It gives you a multiple-inheritance like behaviour. It provides namespace
> also.
>
> On 12/5/06, bigsm...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
<bigsm...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> 
> 
> 
> > Well, I read that chapter before I started this thread :-)

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unknown wrote:
> I understand which purpose modules serve. My question, however, was if
> there''s any
> advantage to defining a module for no other purpose than extending a
> particular class
> instead of just directly changing that class. I hope I didn''t add
more
> confusion to my
> already vague question.
The end result is more or less the same.  However, think of mix-ins as a 
way to extend any class with a set of related functionality.  In this 
respect, a module included into existing classes makes more semantic 
sense.

If you adding a single utility method, simply opening the class would be 
fine.  If you are adding a group of methods that work together toward a 
common functional goal, using a module is preferable since it really 
helps keep things organized and encapsulated.

Also a module name can be auto-documenting.  While the goal of a bunch 
of added method to a base class might be unclear, it makes it easier to 
understand if the name of the module being included is something 
descriptive, such as ActsAsPuppy or GoogleMapsFinder.

-- 
Posted via http://www.ruby-forum.com/.

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On Dec 6, 7:58 pm, Alex Wayne
<rails-mailing-l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
wrote:
> unknown wrote:
> > I understand which purpose modules serve. My question, however,
> > was if there''s any advantage to defining a module for no
other purpose
> > than extending a particular class instead of just directly changing
that class.
> > I hope I didn''t add more confusion to my already vague
question.
>
> The end result is more or less the same.  However, think of mix-ins as a
> way to extend any class with a set of related functionality.  In this
> respect, a module included into existing classes makes more semantic
> sense.
>
> If you adding a single utility method, simply opening the class would be
> fine.  If you are adding a group of methods that work together toward a
> common functional goal, using a module is preferable since it really
> helps keep things organized and encapsulated.
>
> Also a module name can be auto-documenting.  While the goal of a bunch
> of added method to a base class might be unclear, it makes it easier to
> understand if the name of the module being included is something
> descriptive, such as ActsAsPuppy or GoogleMapsFinder.
Thank your very much for your clear description of the pros and cons of
each
approach. This was a much more detailed explanation than I could have
ever
hoped for. :-D


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