From: Marc Heiler <lists@...>
Date: 2012-04-19T02:13:17+09:00
Subject: Why must I know whether I extend a class or a module?

Hi.

I have one module and one class.

module Foo
  def test
    puts 'This is method test() from module Foo.'
  end
end

class Bar
  def test
    puts 'This is method test() from class Bar.'
  end
end


If I want to modify that at a later time, I need
to do something like:

module Foo
  def test
    puts 'Yes, still testing'.
  end
end

Or

class Bar
  # etc..

My question is:

- Why do I need to KNOW that it is a module or a class?

Can't I simply say "I do not care what it is a class or a module, simply
add this method to it."?

I don't understand why I need to explicitely know that one is a module
and the other is a class.

Was there a reason this distinction was used?

I don't have a good alternative though. I thought about:

modify Bar
modify Class

but that would require a new keyword I suppose. And typing "modify" is
also longer than typing class. So there is no real advantage.

So my real question is not so much why things are the way they are or
that I want a change (I don't think there is a good change for it, so
the current way is probably good enough), but my question is:

- Why are things this way? Does anyone know?

PS: On the other hand, when we can god-patch a class or a module, and
undo these changes, perhaps we could also overcome the separation
between classes and modules when I want to modify their behaviour. From
a design point of view, I dont really think it should be needed to know
whether one modifies a module or a class. (Ruby's behaviour could be to
first search for class, then for module.)

-- 
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