#15278: Hash and equality for graphs
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Reporter: SimonKing | Owner:
Type: defect | Status: needs_info
Priority: major | Milestone: sage-6.1
Component: graph theory | Resolution:
Keywords: | Merged in:
Authors: Simon King | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/SimonKing/ticket/15278 | 2fc8a772ee12fce7ac6abc4ecf9916f4746f5ee2
Dependencies: #12601, #15491 | Stopgaps:
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Comment (by ncohen):
Hellooooooooo !!
> The usage is `if getattr(self,'_immutable',False/True): raise
TypeError("...")` (false or true depending on whether we want to allow
something for all graphs except those that are known to be mutable, or
allow something for all graphs except those that are known to be
immutable).
>
> I've never heard before that Python uses it.
Oh. Then I guess we are the only ones to use this `._immutable` flag.
> On the other hand (thinking after writing, as usual...): The optional
arguments of `__copy__` are not used, but when one defines `copy=__copy__`
then the method and its documentation do appear in the docs and can be
used by people. Hm. In the end, it might be better to keep it.
>
> But one question on copying needs to be addressed: I think in some
places in Sage, `copy(X)` returns `X` if `X` is immutable, but in other
places in Sage, `copy(X)` always returns a ''mutable'' copy of `X`,
regardless whether `X` is mutable or not. What would you prefer for
graphs?
>
> In any case, I should add a test showing what happens with copies of
immutable graphs.
Hmmm... Well, I guess it makes more sense to get with "copy" the same kind
of object that was given as input. So copying an immutable graph would
just return the same object. Unless copy is called with an argument
specifying a different implementation of course `O_o`
> Do I understand correctly: You say I shouldn't try to add the "nicer"
syntax now, since you would take care of it in a review patch/other
ticket?
Well, if you feel like doing in this ticket I will gladly review it here.
Otherwise I feel that it would be better to let this ticket be set to
positive review so that you can use it for whatever you have in mind, and
I will write this kind of improvements that are useless to you but would
make my life easier `:-)`
Nathann
--
Ticket URL: <http://trac.sagemath.org/ticket/15278#comment:51>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
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