From: Robert Klemme <shortcutter@...>
Date: 2010-08-23T23:17:18+09:00
Subject: Re: === is not a symmetric operator?

2010/8/23 Ralph Shnelvar <ralphs@dos32.com>:
> Is my understanding correct that === is not a symmetric operator?  That, in fact,
>  X === x
> and
>  x === X
>
> mean different things?

Exactly.

> - - - - -
> irb(main):001:0> class X
> irb(main):002:1> end
> => nil
> irb(main):003:0> x = X.new
> => #<X:0x4d3a660>
> irb(main):004:0> x === X
> => false   # this is surprising
> irb(main):005:0> X === x
> => true    # this is the test I want ... but was surprised when
>           # x === X didn't work.
> irb(main):006:0>
> - - - - -
>
> Does x === X ever mean anything useful?

That depends on what objects x and X refer to.  Remember that X is
only a constant - and not a class or module automatically.

Cheers

robert

-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/