#13394: Write a WeakValueDictionary with safer key removal
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Reporter: nbruin | Owner: rlm
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-5.13
Component: memleak | Resolution:
Keywords: | Merged in:
Authors: Simon King | Reviewers:
Report Upstream: None of the above | Work issues:
- read trac for reasoning. | Commit:
Branch: | fab0ed4112b9f798e2690f4c885b57cd711ea698
u/SimonKing/ticket/13394 | Stopgaps:
Dependencies: |
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Comment (by nbruin):
Even python's `dict` isn't quite properly guarded against mutating
iteration: they only check that the size doesn't change from one yield to
the next, but that isn't enough, of course:
{{{
D=dict( (i,i) for i in range(5))
for k in D:
print "processing key",k
M=max(D.keys())+1
print "adding 10 starting from",M
for i in range(M,M+1000,100): D[i]=1
L=D.keys()[:10]
print "deleting ",L
for j in L: del D[j]
}}}
produces some interesting behaviour. In particular, it iterates 12 times
and results in the keys `[2107, 2108, 3709, 3710, 5311]`. Of course, I
wouldn't know what the program ''should'' do.
--
Ticket URL: <http://trac.sagemath.org/ticket/13394#comment:55>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
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