#11490: Add a thematic tutorial on coercion and categories
---------------------------------------------------------+------------------
Reporter: SimonKing | Owner:
mvngu
Type: enhancement | Status:
needs_review
Priority: major | Milestone:
sage-5.7
Component: documentation | Resolution:
Keywords: categories coercion thematic tutorial | Work issues:
Report Upstream: N/A | Reviewers:
Authors: Simon King | Merged in:
Dependencies: #14084 | Stopgaps:
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Comment (by SimonKing):
Replying to [comment:11 tscrim]:
> - In the `__cmp__` block, it might be worth noting that if `__cmp__` is
not implemented, bad things can happen when calling `cmp` (ex. #14065)
You don't give negative examples in #14065. Do you mean things like the
following?
{{{
sage: class Foo(Element):
....: def __init__(self, x, parent=None):
....: self.x = x
....: def _repr_(self):
....: return "<%s>"%self.x
....:
sage: a = Foo(1,parent=ZZ)
sage: b = Foo(2,parent=ZZ)
sage: cmp(a,b)
Traceback (most recent call last):
...
NotImplementedError: BUG: sort algorithm for elements of 'None' not
implemented
}}}
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11490#comment:16>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
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