#13589: Controlling C3 to solve once for all the Method Resolution Order issues
for
category classes
----------------------------------------------------------+-----------------
Reporter: nthiery | Owner:
nthiery
Type: defect | Status:
needs_review
Priority: major | Milestone:
sage-5.11
Component: categories | Resolution:
Keywords: method resolution order, C3 | Work issues:
Report Upstream: N/A | Reviewers:
Simon King, Florent Hivert
Authors: Nicolas M. Thiéry | Merged in:
Dependencies: #12894, #12876, #11935, #12895, #10193 | Stopgaps:
----------------------------------------------------------+-----------------
Comment (by SimonKing):
Here is another potential improvement:
{{{
sage: cython("""
....: cpdef inline sort_key(object x):
....: return x._cmp_key
....: def test(list L, key):
....: cdef list out = sorted(L, key=key, reverse=True)
....: """)
....:
sage: class C(object):
....: def __init__(self, n):
....: self._cmp_key = n
....:
sage: L = [C(ZZ.random_element(1,10^6)) for _ in range(10000)]
sage: from operator import attrgetter
sage: sk = attrgetter('_cmp_key')
sage: %timeit test(L,sort_key)
100 loops, best of 3: 10.8 ms per loop
sage: %timeit test(L,sk)
100 loops, best of 3: 12.9 ms per loop
sage: %timeit test(L,sort_key)
100 loops, best of 3: 10.8 ms per loop
sage: %timeit test(L,sk)
100 loops, best of 3: 12.9 ms per loop
}}}
So, in C3_controlled, we could implement this cpdef inline function as the
default key for comparison.
In addition, we could decide that the key ''must'' return a tuple, because
this is the format of Category._cmp_key. But this would mean we loose
flexibility.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/13589#comment:49>
Sage <http://www.sagemath.org>
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