From: Eli Bendersky <eliben@...>
Date: 2007-06-16T15:10:08+09:00
Subject: Re: Abstract interfaces as a means of documentation

On Jun 16, 1:53 am, "Gregory Brown" <gregory.t.br...@gmail.com> wrote:
> On 6/15/07, Eli Bendersky <eli...@gmail.com> wrote:
>
> > Is this really different from declaring JumpingClimbingPlayer as a
> > class and inheriting the concrete classes from it, like:
>
> > class FooTypePlayer < JumpingClimbingPlayer
>
> Yes.  Modules cannot be inherited from or instantiated.

Understood, thanks. Another thing - say that for some reason I want my
classes not to have the default .new constructor, and instead use
factory methods (for example, it's important to return values from the
factory methods, other than the object).

In a normal class, I can say:

class Foo
  private_class_method :new

  self.create(a, b)
    ... # do stuff
    return [new(a, b), message]
  end

private
  def initialize(a, b)
     ...
  end
end


But if I want a class family adhering to an abstract interface (like
the previous posts show), how can I do that with a Module ? Module
doesn't allow the "private_class_method" line since it doesn't have
a :new method. With an abstract base Class (instead of Module) it *is*
possible, isn't it ?

Eli