> To make things more clear, the current implementation of Behavior >> #hash
> has two negative side effects:
> - behaviors stored in collections relying on the hash value (e.g. Set,
> Dictionary) will have to be rehashed whenever a behavior is renamed
> - objects using Behavior >> #hash to implement their own #hash, like what
> Eliot just did to Message will suffer from the same issue. So Sets and
> Dictionaries holding those kind of objects will have to be rehashed as
> well upon the rename of the behavior.
>
> My questions related to this:
> - why does Behavior >> #hash rely on the name instead of identity?

If you mean #identityHash, then its because involving an unstable
value in a #hash calculation is never a good idea.  #identityHash can
be different for the same class between two different images, or if
the class was ever becomed or reloaded into a new image, etc.

> - do we want to fix those issues mentioned above or do we just say that
> one should not rename classes and expect things to work?

Neither.  We just say that when one renames a class to rehash all
relevant HashedCollections.

 - Chris