#9016: make morphisms hashable
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Reporter: burcin | Owner: AlexGhitza
Type: enhancement | Status: needs_info
Priority: major | Milestone: sage-4.7.1
Component: categories | Keywords:
Work_issues: | Upstream: N/A
Reviewer: Robert Bradshaw | Author: Burcin Erocal
Merged: | Dependencies:
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Comment(by burcin):
I don't see how the string representation could provide more information
than the data stored in the class. I would be happy to add such data to
the tuple that is hashed if you point it out.
The current patch uses the hash of the images of the generators when the
morphism class contains this information. See line 1103 of
`sage/rings/morphism.pyx` for example. In order to implement your
suggestion we would also have to change the comparison functions, which
compare the same data this patch hashes.
<rant>
Robert, even though you chose to mark this as an enhancement in comment:3,
it is actually a bug that effects my work. The category framework relies
heavily on cached functions, which in turn need the arguments of these to
be hashable. For example, I need unique parents that also depend on a
morphism/map (difference/differential rings). I opened this ticket when I
ran into this problem a year ago. I know I haven't really pushed it
through, but it still is a shame that it takes so long for such a small
change to get into a release.
</rant>
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/9016#comment:12>
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