#17890: Remove _(rich)cmp_c_impl
-------------------------------------+-------------------------------------
Reporter: jdemeyer | Owner:
Type: enhancement | Status: needs_info
Priority: major | Milestone: sage-6.6
Component: cython | Resolution:
Keywords: | Merged in:
Authors: Jeroen Demeyer | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/jdemeyer/ticket/17890 | 313a400146b0fb19d80c31117d44ce735041d4ec
Dependencies: | Stopgaps:
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Changes (by vdelecroix):
* status: needs_review => needs_info
Comment:
9. implementation of `_(rich)cmp`:
- Why in `_(rich)cmp` it starts with the case `not
have_same_parent_c(left,right)` instead of
`have_same_parent_c(left,right)`. It would make it more readable the other
way around.
{{{
cdef _richcmp(left, right):
if have_same_parent_c(left, right):
return left._richcmp_(<Element>right, op)
# different parents
global coercion_model
cdef int r
...
}}}
- In `return left._(rich)cmp_(<Element>right, op)` is the `<Element>`
really needed or usefull?
- could `_left, _right = coercion_model.canonical_coercion(left, right)`
be replaced with `left, right = coercion_model.canonical_coercion(left,
right)`. As far as I see, there is no need of these extra variables.
10. Could you some minimal documentation to `_(rich)cmp` and `_(rich)cmp_`
like
{{{
def _richcmp(left, right):
r"""
Rich comparisons of elements
This should not be overriden! To implement comparisons override
``_richcmp_``
or/and ``_cmp_``.
"""
def _richcmp_(left, right):
r"""
Default implementation of rich comparisons for elements
By default it tries to see if `_cmp_` is implemented otherwise does a
comparison by id for ``==`` and ``!=``. Calling this default method
with ``<``, ``<=``, ``>`` or ``>=`` will raise a
``NotImplementedError``.
EXAMPLES::
sage: from sage.structure.parent import Parent
sage: from sage.structure.element import Element
sage: P = Parent()
sage: e1 = Element(P); e2 = Element(P)
sage: e1 == e1 # indirect doctest
True
sage: e1 == e2 # indirect doctest
False
sage: e1 < e2 # indirect doctest
Traceback (most recent call last):
...
NotImplementedError: comparison not implemented for
<type 'sage.structure.element.Element'>
"""
}}}
and I think that `_cmp_` and `_richcmp_` deserves a sphinx directive to
make them appear in the reference manual.
--
Ticket URL: <http://trac.sagemath.org/ticket/17890#comment:51>
Sage <http://www.sagemath.org>
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