#9429: Undesirable behaviour when deriving from QuotientRingElement
-----------------------+----------------------------------------------------
Reporter: vbraun | Owner: AlexGhitza
Type: defect | Status: new
Priority: major | Milestone:
Component: algebra | Keywords:
Author: | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
-----------------------+----------------------------------------------------
All arithmetic operations on `QuotientRingElement` return a new
`QuotientRingElement`, which is not the desired result for derived
classes. Instead one should use `self.__class__` to return an instance of
the actual type:
{{{
sage: from sage.rings.quotient_ring_element import QuotientRingElement
sage: class Q(QuotientRingElement):
... pass
...
sage: P.<x,y> = PolynomialRing(QQ, 'x, y')
sage: Pquo = P.quo(x^3)
sage: q = Q(Pquo, x)
sage: type(q)
<class '__main__.Q'>
sage: type(q^2)
<class 'sage.rings.quotient_ring_element.QuotientRingElement'>
}}}
Expected behaviour: `q^2` should have the same (derived) type as `q`.
I am running into this issue because I want to express cohomology classes
on toric varieties as derived classes of `QuotientRingElement`, see #9326.
I'll write the obvious patch and attach it later today.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/9429>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
--
You received this message because you are subscribed to the Google Groups
"sage-trac" group.
To post to this group, send email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/sage-trac?hl=en.
