Hi Eliot,


I'm not deep in this stuff, but I always try to keep maximum flexibility in terms of polymorphy when designing any interface in Squeak. Thus my naive choice would be option 3, ignore it and hope the user knows what they're doing. Using of #isKindOf: etc. often can lead to problems, for example, imagine an association being wrapped within a proxy or an ObjectTracer ... Just my 2 cents :)


Best,

Christoph

<http://www.hpi.de/>
________________________________
Von: Squeak-dev <squeak-dev-bounces at lists.squeakfoundation.org> im Auftrag von Eliot Miranda <eliot.miranda at gmail.com>
Gesendet: Donnerstag, 1. Oktober 2020 19:44:46
An: The general-purpose Squeak developers list
Betreff: [squeak-dev] Ephemerons and Dictionaries

Hi All,

    to be able to ease EphemeronDicitonary into the system easily I'd like to clean up adding associations to Dictionary.  It seems to me there's a partial implementation of choosing an association class appropriate for a dictionary in the implementors of associationClass: Dictionary>>#associationClass, WeakKeyDictionary>>#associationClass, WeakValueDictionary>>#associationClass, (& in my image STON class>>#associationClass).  This seems workable; an EphemeronDictionary would simply add associationClass ^ Ephemeron and we're done, except not quite...

First, HashedCollection does not use associationClass, but it implements atNewIndex:put: and it strikes me that atNewIndex:put: for Dictionary really should check for the thing being added at least includingBehavior: self associationClass.  So that means Dictionary should override atNewIndex:put:.

But what should happen in atNewIndex:put: if the object being added isn't appropriate?  Do we
- raise an error? (that's my preference, but I've got limited use cases in my head)
- replace the association with one of assocationClass? (seems dangerous to me but maybe someone needs this or the existing system does this anyway)
- ignore it and hope the user knows what they're doing?



_,,,^..^,,,_
best, Eliot
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