#12510: Add consistency tests for __nonzero__ in TestSuite.
---------------------------+------------------------------------------------
Reporter: hivert | Owner: hivert
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-5.0
Component: categories | Keywords:
Work_issues: | Upstream: N/A
Reviewer: | Author: Florent Hivert
Merged: | Dependencies:
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Description changed by hivert:
Old description:
> With many datastructure for elements, comparison to zero could be faster
> than
> comparison of two elements. The pythonic way to do that is to use
> indirectly
> {{{e.__nonzero__()}}} for example in {{{if not e: ...}}}. However, to be
> able
> to use consistently this idiom, we have to make sure that the return
> value of
> {{{e == e.parent().zero()}}} agrees with {{{bool(e)}}}. The purpose of
> this
> patch is to add this tests to the standard test suite and to fixe the
> Sage
> library according to this policy.
>
> On the way, I discovered that for a some morphism of modules, pickling
> can be
> broken if the zero morphism is asked. I also fixes this issue.
>
> See also discussion on #12508
New description:
With many datastructure for elements, comparison to zero could be faster
than
comparison of two elements. The pythonic way to do that is to use
indirectly
{{{e.__nonzero__()}}} for example in {{{if not e: ...}}}. However, to be
able
to use consistently this idiom, we have to make sure that the return value
of
{{{e == e.parent().zero()}}} agrees with {{{bool(e)}}}. The purpose of
this
patch is to add this tests to the standard test suite and to fixe the Sage
library according to this policy.
On the way, I discovered that for a some morphism of modules, pickling can
be
broken if the zero morphism is asked. I also fixes this issue.
See also discussion on #12508. Finally, I left to #12526 the question of
removing {{{__nonzero__}}} from element and writing tuned implantation for
all data structures.
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/12510#comment:4>
Sage <http://www.sagemath.org>
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