#13814: LazyFamily.__eq__ gives false positives.
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Reporter: cnassau | Owner: sage-combinat
Type: defect | Status: needs_review
Priority: major | Milestone: sage-5.6
Component: combinatorics | Resolution:
Keywords: | Work issues:
Report Upstream: N/A | Reviewers:
Authors: Christian Nassau | Merged in:
Dependencies: | Stopgaps:
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Comment (by nthiery):
Replying to [comment:16 cnassau]:
> I have implemented a new patch, based on Sage 5.5.rc0. Here are the key
features:
>
> The new {{{LazyFamily.__eq__}}}
>
> * does not compare function values (even if the indexing set is
finite)
> * recognizes identical function objects
> * uses {{{self.function.__eq__}}} if this is available
> * otherwise treats functions as distinct
>
> Furthermore
>
> * "{{{f != g}}}" is exactly equivalent to "{{{not(f==g)}}}"
Great, thanks!
> Contrary to my expectations there were not that many doctest failures.
The only affectes files were ``family.py`` and
``disjoint_union_enumerated_sets.py``.
That's definitely good news.
Should I remove the previous patch? Then we won't have to specify
which patch to apply.
A couple questions:
Would there be a problem to just compare the functions with:
{{{
self.function == other.function
}}}
Rather than doing the check for is and then for eq?
I am surprised about your comment about Permutations not being
picklable. This works for me:
{{{
sage: P = Permutations(3)
sage: P == Permutations(3)
True
sage: P == loads(dumps(P))
True
}}}
Could the hash be calculated using both the hash of the indexing set
and the function?
Please take the occasion to rewrite {{{WARNING}}} into
{{{.. WARNING::}}} (see the developers manual for the exact syntax).
Where is ``!=`` implemented?
Cheers,
Nicolas
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/13814#comment:17>
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