From: Ralph Shnelvar <ralphs@...32.com>
Date: 2010-09-15T04:52:45+09:00
Subject: Extend & Declarative relations between object attributes

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Sunday, September 12, 2010, 6:19:53 PM, you wrote:

JV> # Let's just include Observable globally. Conservatively, one would do:
JV> #
JV> #   class C
JV> #     extend Observable
JV> #     include Observable::Match   # if desired
JV> #     ...
JV> #   end

I give.  What does
  extend Observable
do?

I see in Dave Thomas' *Programming Ruby 1.9* that extend "Adds to obj the instance methods from each module given as a parameter".

So ... what object is "extend Observable" referring to?  The class C object? (That is, the class that is C rather than the instance that is C.)  Is this related to some singleton stuff?

And how is the extend different than the include?


Ralph
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