From: Robert Klemme <shortcutter@...>
Date: 2010-08-24T00:20:42+09:00
Subject: Re: === is not a symmetric operator?

2010/8/23 Ralph Shnelvar <ralphs@dos32.com>:
> Matz,
>
> Monday, August 23, 2010, 8:17:30 AM, you wrote:
>
> YM> Hi,
>
> YM> In message "Re: === is not a symmetric operator?"
> YM>     on Mon, 23 Aug 2010 22:52:11 +0900, Ralph Shnelvar <ralphs@dos32.com> writes:
>
> YM> |Is my understanding correct that === is not a symmetric operator?  That, in fact,
> YM> |  X === x
> YM> |and
> YM> |  x === X
> YM> |
> YM> |mean different things?
>
> YM> No.
>
> No!?!?!?! ... They do mean the same thing?!?!?!?
>
> Or ... "No, they do not mean the same thing."?

Well, in a way they mean the same thing, i.e. method :=== is invoked
on the left instance and the right instance is passed as argument.
How :=== is implemented completely depends on the class (or even
instance) at hand.  Conventionally there is an implementation for
Class and Module which tests for "instance of" relation.  And for
regular expressions :=== implements regexp matching.  Etc.

Cheers

robert

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