#14535: Mutability of Graphs
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Reporter: SimonKing | Owner: jason, ncohen, rlm
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-5.10
Component: graph theory | Resolution:
Keywords: mutability graph | Work issues:
Report Upstream: N/A | Reviewers:
Authors: Simon King, Volker Braun | Merged in:
Dependencies: #14524 | Stopgaps:
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Comment (by ncohen):
> whether or not there is an immutable backend doesn't change the fact
that we want to mark mutable graphs as immutable.
If you just want to mark the `Graph` object as immutable, then that does
not prevent you from changing the backend while you are at it. Doing so
may mean that you get better performances for the adjacency tests later on
if a real immutable backend is implemented somewhere.
> Unless you always want to copy the graph data in that step, it will
always require you to check a mutability flag.
Once more : checking that the graph is immutable is fine with me if you
must do it this way, and I will try to save this by writing an immutable
graph backend later on. What I want to avoid is a slowdown in current
graphs methods.
I expect that, as you say, check a cdef boolean value would not produce a
significant slowdown, while the current patch based on decorators does
produce a slowdown.
Nathann
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Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/14535#comment:35>
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