Actually, #= and #hash should be defined so: if (a=b) then a hash = b hash if a != b, it's not important This is required because some collections (like sets, dictionaries) will index their elements by their hash. Then, typically the collection implementation will first ask the hash, access the index with it, and retrieve the object if it is = only. Notice that several objects can have the same hash but be equals nonetheless. On Thu, Aug 16, 2018 at 11:36 AM Jan Blizničenko <bliznjan@fit.cvut.cz> wrote:

Hello, I've been looking at implementation of Associtation and LookupKey (its superclass). In LookupKey, there is LookupKey>>#= and LookupKey>>#hash both implemented to use key (compare keys and use hash of key), but in Association, Association>>#= compares both key and value, but hash is not changed there, so only hash of key is used, therefore it does not correspond to implementation of method = ... shouldn't it?

To demonstrate: (1 -> #a) = (1 -> #b). is false but (1 -> #a) hash = (1 -> #b) hash. is true

I also noticed similar discussion for Doplhin smalltalk http://forum.world.st/Association-gt-gt-hash-td3368868.html where guys state it is all right, but I still do not see why.

Jan

-- Sent from: http://forum.world.st/Pharo-Smalltalk-Developers-f1294837.html

-- Guille Polito Research Engineer Centre de Recherche en Informatique, Signal et Automatique de Lille CRIStAL - UMR 9189 French National Center for Scientific Research - *http://www.cnrs.fr <http://www.cnrs.fr>* *Web:* *http://guillep.github.io* <http://guillep.github.io> *Phone: *+33 06 52 70 66 13