[squeak-dev] [Cuis-dev] Message>>#= & Message>>#hash
David T. Lewis
lewis at mail.msen.com
Tue Nov 20 00:32:24 UTC 2018
On Mon, Nov 19, 2018 at 04:16:51PM -0800, Eliot Miranda via Cuis-dev wrote:
> Hi David,
> On Mon, Nov 19, 2018 at 9:52 AM David T. Lewis <lewis at mail.msen.com> wrote:
> > On Mon, Nov 19, 2018 at 09:32:17AM -0800, Eliot Miranda wrote:
> > > Hi All,
> > >
> > > In VisualWorks Message implements #= & #hash naturally; two messages
> > > whose selectors and arguments are #= are also equal. But in Cuis, Squeak
> > > and Pharo Message inherits #= and #hash from Object, i.e. uses identity
> > > comparison. This is, to say the least, annoying. Any objections to
> > > implementing comparing in Message to match VisualWorks?
> > >
> > That sounds like an obviously good thing to do :-)
> > Is the lookupClass instance variable relevant for comparisons? I am
> > guessing not, since we already have #analogousCodeTo: for that type of
> > comparison.
> For me it is relevant. Two messages with different lookupClasses, e.g. one
> with nil and one with a specific class, represent different messages, one a
> normal send one a super send. So my changes in waiting include lookupClass
> in both hash and =. I don't think it makes much difference, but the
> incompatibility with VisualWorks, while regrettable, feels correct to me.
That feels correct to me also. But implementation details and bikeshedding
aside, I would be happy if "Message allInstances asSet asArray" could answer
a reasonably small collection of different-looking things. So +1 to the
change, with or without consideration of lookupClass.
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