From: Paul Brannan <pbrannan@...>
Date: 2001-10-10T03:12:41+09:00
Subject: [ruby-talk:22327] include vs. extend

The recent talk about mixins recently has made me curious.  I have a
collection of about 15 mixins that currently get included, in various
combinations, in 5 different classes.  Right now, I'm doing something like
this:

  class Foo
    include M1
    include M2
    include M3
    include M4
  end

But it's also possible to do something like this:

  class Bar
    def initialize
      extend M1
      extend M2
      extend M3
      extend M4
    end
  end

Both solutions seem to work equally well; if I add a new method to M4, for
example, then the method gets added to all existing objects of Foo and
Bar.  The first solution seems to be MUCH faster if a lot of objects are
created/destroyed.  The second solution seems to be a LITTLE faster if
there is one object, but many calls to methods in M1..M4.

1) Is there any other solution that gives me a better tradeoff in terms of
speed?

2) What are some advantages/disadvantages to each solution that I have
not considered?

Paul