[squeak-dev] true hash
Chris Muller
asqueaker at gmail.com
Wed May 9 20:46:38 UTC 2012
> Why would you depend on the exact value of the identity hash?
Not the value of the identityHash, the value of the hash.
> When writing a new image and the identity hash changed, then obviously all dictionaries would have to be rehashed. Seems like a non-issue to me.
That's the exact problem I want to avoid. Think in the context of a
multiuser client-server app accessing the same large persistent domain
model. The domain model includes a complex domain object used as a
key in a dictionary, and one of the attributes used to determine its
hash is one of its boolean attributes.
Now, some of the clients suddenly happen to get a new #identityHash
for true, which in turn changes its #hash. Now they cannot access the
domain's whose hash depends on true or false. Worse, they might
#at:put: into it and then the model is "corrupted" because there is no
universally-consistent notion of true's hash across all client images.
You're right, I could add my own private extensions, but we should
consider having "universal" atomics given the the aforementioned
insidiousness of the above situation..?
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