#16269: Cartesian Products of additive groups
-------------------------------------+-------------------------------------
Reporter: ncohen | Owner:
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-6.2
Component: categories | Resolution:
Keywords: | Merged in:
Authors: Nathann Cohen, | Reviewers:
Nicolas M. Thiéry | Work issues:
Report Upstream: N/A | Commit:
Branch: u/ncohen/16269 | d22e245049e26dd10522d3514603868701a286fb
Dependencies: | Stopgaps:
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Comment (by nthiery):
Hi!
I have just been through the changes. Overall, it looks good, thanks!
Remaining points:
- CartesianProduct.__iter__ should be in
EnumeratedSets.CartesianProducts.ParentMethods
- In ``_add_``, ``self.parent(right)`` looks suspicious. Does it even
work?
If the purpose is to convert ``right`` into the same parent as
``self``, then no need to worry about this: ``_add_`` may assume
that its two arguments belong to the same parent.
- I am uncomfortable with using ``__iter__`` and ``__getitem__`` for
accessing the components of an element. For certain cartesian
products (e.g. cartesian products of modules), ``__iter__`` may have
a different meaning. Please use ``summand_split`` and
``summand_projection`` instead.
- In ``_element_constructor_``: given the catch, if we feed completely
unrelated crap to the constructor, is there an exception raised as
one could desire?
{{{
sage: GF(3)("a")
Traceback (most recent call last)
...
TypeError: unable to convert x (=a) to an integer
sage: C = cartesian_product([GF(3), GF(3)])
sage: C(["a","b"])
???
}}}
Please add this doctest. Btw, one might also want to raise a meaningful
error if the length of `x` is incorrect.
Cheers,
Nicolas
--
Ticket URL: <http://trac.sagemath.org/ticket/16269#comment:17>
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