From: Mark Hahn <mchahn@...>
Date: 2001-11-01T00:58:32+09:00
Subject: [ruby-talk:23969] Re: Overiding a method in another module

Thanks.

It kind of bothers me that I may have hundreds of lines of Ruby that need to
be eval'd when I know eval is slow.  This seems like a bit of a kludge.  My
code will look funny to have eval around every method.

Whenever I smell a kludge, I always must ask is it me or the language.  I
think the answer to this lies in whether what I am trying to do is an
"acceptable OO practice".  Is it acceptable to want to add methods to
someone else's module?

Here is the situation that I am facing (see below).  I want to add method
m_2 to class C1 and make sure instances of C2 (any any other subclass of C1)
respond to m_2.  I cannot subclass C1 to accomplish this because I have no
way to change C2 to subclass my new subclass.  I cannot change the source of
M1 because of the license.  Even if there wasn't a license issue, isn't
reusability all about using other code without changing it?

module M1    << This is other person's module
  class C1
    def m_1
      ...
    end
  end
  class C2 < C1
    ...
  end
end

module M2     << This is my module
  class M1::C1
    def m_2   << I need instances of C2 to call this
      ...
    end
  end
end

I don't see how even multiple inheritance would help this situation.

Can someone tell me a "clean", non-eval way of doing this?  How do other
languages handle this?


-----Original Message-----
From: David Alan Black [mailto:dblack@candle.superlink.net]
Sent: Tuesday, October 30, 2001 5:29 PM
To: ruby-talk ML
Subject: [ruby-talk:23895] Re: Overiding a method in another module


On Wed, 31 Oct 2001, David Alan Black wrote:

> You can do this:
[...]
>     M1::C1.class_eval <<EOE

or even just:

   C1.class_eval <<EOE

since M1 has been included.


David

--
David Alan Black
home: dblack@candle.superlink.net
work: blackdav@shu.edu
Web:  http://pirate.shu.edu/~blackdav