#15278: Hash and equality for graphs
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Reporter: SimonKing | Owner:
Type: defect | Status: needs_work
Priority: major | Milestone: sage-6.1
Component: graph theory | Resolution:
Keywords: | Merged in:
Authors: Simon King | Reviewers: Nathann Cohen
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/SimonKing/ticket/15278 | fcf9e3018d5e87f49e1f3f3d68ad4cc49382c0b9
Dependencies: #12601, #15491 | Stopgaps:
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Comment (by SimonKing):
Replying to [comment:67 ncohen]:
> This being said, checking the backend does not exactly mean that all
other properties of graphs are "protected", like the embedding and
everything.
That's why ''both'' the flag and the type of the backend are checked
before returning "self" as a copy.
> Okay, I just read your latest post : the point is that this ._immutable
flag is a hack. Shouldn't we just make their code use the new backend, so
that their code is not hacked anymore ? Right now they claim their graphs
are immutable, though they aren't. Seems like the way to go, isn't it ?
In a way, yes. In a different way: Are we supposed to clean up their mess?
If they use the static backend, as they should, then the should also let
`copy()` create a ''mutable'' copy; hence, each usage of `copy()` should
be decorated with an optional argument (such as: `sparse=True`) which
makes the copy be an actual mutable copy of the graph. So, it is more to
do than just changing the backend, since in some places they pretend to
have immutable graphs, but in others they want to mutate a copy of the
graph.
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Ticket URL: <http://trac.sagemath.org/ticket/15278#comment:71>
Sage <http://www.sagemath.org>
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