#9016: make morphisms hashable
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Reporter: burcin | Owner: AlexGhitza
Type: defect | Status: needs_review
Priority: major | Milestone: sage-4.4.3
Component: algebra | Keywords:
Author: Burcin Erocal | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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Changes (by burcin):
* cc: robertwb (added)
* status: new => needs_review
Comment:
There seems to be a problem with inheriting `__hash__()` methods. The
class `sage.categories.morphism.SetMorphism` derives from
`sage.categories.morphism.Morphism` which in turn derives from
`sage.categories.map.Map`.
Even after adding a `__hash__()` method to `sage.categories.map.Map`,
instances of `SetMorphism` are not hashable:
{{{
sage: from sage.categories.morphism import SetMorphism
sage: X.<x> = ZZ[]
sage: Y = ZZ
sage: phi = SetMorphism(Hom(X, Y, Rings()), lambda p: p[0])
sage: hash(phi)
---------------------------------------------------------------------------
TypeError Traceback (most recent call
last)
/home/burcin/sage/sage-4.4.1.alpha2-patched/<ipython console> in
<module>()
TypeError: unhashable type: 'sage.categories.morphism.SetMorphism'
}}}
Note also that `sage.categories.map.Map` derives from
`sage.structure.element.Element` which also has a `__hash__()` method.
Any hints?
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/9016#comment:1>
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