#10651: Make a good use of the EmptySetError in EnumeratedSets and Parent
---------------------------------------------------------------+------------
Reporter: nborie | Owner:
nborie
Type: defect | Status:
needs_review
Priority: major | Milestone:
sage-4.7
Component: categories | Keywords:
days28, empty set, EmptySetError
Author: Nicolas Borie, Nicolas M. Thiéry | Upstream:
N/A
Reviewer: Paul Zimmermann, Robert Bradshaw, Nicolas Borie | Merged:
Work_issues: |
---------------------------------------------------------------+------------
Changes (by newvalueoldvalue):
* status: needs_work => needs_review
* author: Nicolas Borie => Nicolas Borie, Nicolas M. Thiéry
* cc: hivert (removed)
* cc: nthiery (added)
* reviewer: Paul Zimmermann => Paul Zimmermann, Robert Bradshaw, Nicolas
Borie
Old description:
> As Florent Hivert gave extremely useful features about empty things, we
> should use it. The Following should returns an EmptySetError
> {{{
> sage: S = Set([])
> sage: S.an_element()
> ---------------------------------------------------------------------------
> StopIteration Traceback (most recent call
> last)
>
> /opt/sage/devel/sage-combinat/<ipython console> in <module>()
>
> /opt/sage/local/lib/python2.6/site-packages/sage/misc/cachefunc.pyc in
> __call__(self, *args, **kwds)
> 329 2
> 330 """
> --> 331 return self._cachedmethod._instance_call(self._instance,
> *args, **kwds)
> 332
> 333 def get_cache(self, *args, **kwds):
>
> /opt/sage/local/lib/python2.6/site-packages/sage/misc/cachefunc.pyc in
> _instance_call(self, inst, *args, **kwds)
> 473 return cache[key]
> 474 else:
> --> 475 cache[key] = self._cachedfunc.f(inst, *args, **kwds)
> 476 return cache[key]
> 477
>
> /opt/sage/local/lib/python2.6/site-
> packages/sage/categories/enumerated_sets.pyc in
> _an_element_from_iterator(self)
> 470 """
> 471 it = self.__iter__()
> --> 472 return it.next()
> 473
> 474 # Should this be implemented from first instead?
>
> StopIteration:
> sage:
> }}}
New description:
As Florent Hivert gave extremely useful features about empty things, we
should use it. The Following should returns an EmptySetError
{{{
sage: S = Set([])
sage: S.an_element()
---------------------------------------------------------------------------
StopIteration Traceback (most recent call
last)
...
StopIteration:
sage:
}}}
Also, make the EmptySetError being documented already in the structure of
Parent. Improve the documentation of an_element and _an_element_ in
Parent.
--
Comment:
In order to fix more things in the same time, I update the description of
this ticket. I folded the NT'reviewer from the sage-combinat queue, then I
uploaded the patch with a better commit message.
I am very OK with the changes in the Parent structure from Nicolas Thiéry.
I give a positive review on all changes touching the corresponding file.
The first part of the patch still comes from me, so no review from me.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10651#comment:14>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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