From: pjb@... (Pascal J. Bourguignon)
Date: 2008-03-11T18:34:55+09:00
Subject: Re: Which is better -- method option or multiple methods?

Trans <transfire@gmail.com> writes:

> In the case of limited options, like the following example, which is
> better?
>
> class String
>
>   def align(direction. spacing)
>     case direction
>     when :left
>       ...
>     when :right
>       ...
>     when :center
>       ...
>     end
>   end
>
> OR
>
>   def align_left(spacing)
>     ...
>   end
>
>   def align_right(spacing)
>     ...
>   end
>
>   def align_center(spacing)
>     ...
>   end
>
> Thanks,
> T.
>

OR:

   def align(direction. spacing)
      insertSpaces( 4 * @@mapDirectionsToOffset[direction] );
   end

That is, you could choose between one form or the other depending on
whether the method is continuous or discontinuous on that argument.
If you have to write a case, then use several methods.  If you can
define a single formula, then use a single method.

Becareful in spite of my formulation, this choice should be done from
an abstract point of view, is the essence of this parameter to
influence the method in a discontinuous way or a continuous way?
Because we're talking here of the interface, and this interface should
speak of the essence of things, not of their implementation details.


-- 
__Pascal Bourguignon__