Opened 5 years ago
#23212 new defect
Move non-unique-parent code later in _internal_coerce_map
Reported by: | roed | Owned by: | |
---|---|---|---|
Priority: | major | Milestone: | sage-8.0 |
Component: | coercion | Keywords: | sd86.5 |
Cc: | Merged in: | ||
Authors: | Reviewers: | ||
Report Upstream: | N/A | Work issues: | |
Branch: | Commit: | ||
Dependencies: | Stopgaps: |
Description
Currently, coercions between equal-but-not-identical parents are always of type DefaultConvertMap
or DefaultConvertMap_unique
because of a certain code path in Parent._internal_coerce_map
. For example,
sage: V = VectorSpace(QQ,1) sage: W = V.subspace([V.gen(0)]) sage: type(V.coerce_map_from(W)) <type 'sage.structure.coerce_maps.DefaultConvertMap_unique'>
Compare with
sage: V = VectorSpace(QQ,2) sage: W = V.subspace([V.gen(0)]) sage: type(V.coerce_map_from(W)) <class 'sage.modules.vector_space_morphism.VectorSpaceMorphism'>
Presumably VectorSpaceMorphism
s have useful functionality, and we don't want to throw it away in this edge case.
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