From: Rob Biedenharn <Rob@...>
Date: 2008-05-24T02:51:50+09:00
Subject: Re: Module.===(X,X) is false

On May 23, 2008, at 1:44 PM, calfeld@mac.com wrote:

> Thanks for all the feedback.
>
> I'm aware of the usual use of Module.===, namely to check if an object
> is an instance of a class or descendent of that class.
>
> My issue is not with when Module.=== is true, my issue is with a
> specific example of when it is false.  Namely, that, for a class (not
> an instance) X, the following is true:
>
>  (! (X === X)) && (X == X)
>
> This surprises me, and denies me the ability to compare a class (an
> instance of Class) to its possible values (instances of Class) in a
> case statement.
>
> Thanks again,
>  c.


But what about X = Class? ;-)

You can always use 'case' like an 'if'

Foo = Class.new
[Foo, Foo.new].each_with_index do |i,position|
   print "#{position}: "
   case
   when Foo == i
     puts 'i is the class Foo'
   when Foo === i
     puts 'i is an instance of Foo'
   end
end

-Rob

Rob Biedenharn		http://agileconsultingllc.com
Rob@AgileConsultingLLC.com