[BUG] Dictionary equality test

Chris Muller afunkyobject at yahoo.com
Mon Jun 17 15:25:17 UTC 2002


Richard O'Keefe responded:
> There is no such animal.
> ...
> Date I'll buy.

;-)

> I have no idea what Customer is; there is no such class in my copy of Squeak.

Of course you don't, I was speaking in general terms.  Maybe I should have said
that the message = with things other than values are *overly* ambiguous,
meaning you lose the value in the selector.  This sort of addresses Bob Arnings
reply as well.  He said, "If you're using it, you should KNOW what it does,"
presumably by having checked the implementation.  But we don't check the
implemenation of each and every method we ever use for the first time because,
thankfully, the selector, in context of its class, is intention-revealing
enough to put it *below* the threshold of ambiguity.

Now, if you stretch out that context to the mathematical extremes you did, yes,
there may be a small traces of potential ambiguity.

> Crack open any set theory textbook, and it'll be somewhere around page
> 3 of chapter 1.  It's one of the fundamental rules of set theory.

Well, if Squeak is intended for children, we may want to move Set theory way up
into the elementary curriculum..  ;-)

Honestly, if I had to guess a single meaning of Set>>=, I would have guessed
what it currently does.  I probably wouldn't, however, for Dictionary, Bag and
OrderedCollection.  What does the Set theory book say about those?

> on pp 108-109 of Common Lisp, the Language, 2nd edition:
> Two hash tables are considered the same ... if and only if
> they satisfy a four-part test:

Wow, all that meaning in one little = message!  Hey, I can't disagree with the
mathematical definitions you've referenced, a less ambiguous message name is
more productive.

It is not my intent to stifle any improvements to the Collection classes.  I am
all for mathematical rigor as much as possible!  I may have been misunderstood
on my remarks that encourage people to share objects instead of implementing =,
but it looks like were probably out of context of this discussion anyway. 
Please accept my apology if they were..

Regards,
  Chris


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