#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):
Something findings:
- C3_sorted_merge was called 121 times with the current patch during
startup.
- C3_sorted_merge is called on different Groupoids, which should not
happen, because all groupoids have the same super categories. Solution:
Make it `CategoryWithParameters`. Then, C3_sorted_merge is only called 93
times during startup.
- There are some optimizations possible in C3_sorted_merge:
{{{
sage: L1 = Fields().all_super_categories()
sage: L2 = Algebras(QQ).all_super_categories()
sage: cython("""
def test1(list L):
cdef list out = L[::-1]
def test2(list L):
cdef list out = list(reversed(L))
""")
....:
sage: %timeit test1(L1)
1000000 loops, best of 3: 541 ns per loop
sage: %timeit test2(L1)
100000 loops, best of 3: 2.25 us per loop
}}}
and
{{{
sage: cython("""
....: def test1(list L):
....: cdef set S = set(x for x in L)
....: def test2(list L):
....: cdef set S = set([x for x in L])
....: """)
....:
sage: %timeit test1(L1)
100000 loops, best of 3: 3.91 us per loop
sage: %timeit test2(L1)
100000 loops, best of 3: 3.99 us per loop
sage: %timeit test1(L1)
100000 loops, best of 3: 3.89 us per loop
sage: %timeit test1(L1)
100000 loops, best of 3: 3.89 us per loop
sage: %timeit test2(L1)
100000 loops, best of 3: 4.06 us per loop
}}}
In both examples above, test2 is what is currently done in
C3_sorted_merge, and test1 is apparently what ''should'' be done. I am
preparing a patch now.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/13589#comment:45>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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