#17890: Remove _(rich)cmp_c_impl
-------------------------------------+-------------------------------------
Reporter: jdemeyer | Owner:
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-6.7
Component: cython | Resolution:
Keywords: | Merged in:
Authors: Jeroen Demeyer | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/jdemeyer/ticket/17890 | 04570b3dfd194fea8c2437c8717c3dfb8704b4af
Dependencies: | Stopgaps:
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Comment (by vdelecroix):
I would really like the following in `Element._richcmp_`
{{{#!diff
diff --git a/src/sage/structure/element.pyx
b/src/sage/structure/element.pyx
index 6981135..12cb669 100644
--- a/src/sage/structure/element.pyx
+++ b/src/sage/structure/element.pyx
@@ -1047,11 +1047,21 @@ cdef class Element(SageObject):
...
NotImplementedError: comparison not implemented for <type
'sage.structure.element.Element'>
"""
# Obvious case
if left is right:
return rich_to_bool(op, 0)
cdef int c
+ if op == Py_NE:
+ try:
+ left_eq = left.__eq__
+ except AttributeError:
+ pass
+ else:
+ if isinstance(left_eq, MethodType):
+ return False if left_eq(right) else True
+
try:
c = left._cmp_(right)
except NotImplementedError:
}}}
that would allow element implementing `__eq__` to benefit of `__ne__` for
free. What do you think? Perhaps not for this ticket though (thinking
about #18305). It is a bit dangerous since `__eq__` would not go through
coercions but `__ne__` would.
--
Ticket URL: <http://trac.sagemath.org/ticket/17890#comment:62>
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