#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:
Vincent Delecroix, Travis Scrimshaw
Authors: Simon King | Merged in:
Dependencies: #14084 | Stopgaps:
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Comment (by SimonKing):
By the way, it is a bit ironical:
{{{
sage: Q.gen()
Traceback (most recent call last):
...
RuntimeError: NewFrac(Univariate Polynomial Ring in x over Integer Ring)
still using old coercion framework
}}}
I think that this error is totally misleading. Clearly, the new coercion
model is used, is it not?
The test against the old coercion model simply asks whether
`P._element_constructor` is not None:
{{{
cdef inline check_old_coerce(parent.Parent p):
if p._element_constructor is not None:
raise RuntimeError, "%s still using old coercion framework" % p
}}}
Since `P._element_constructor` now seems to coincide with
`P._element_constructor_`, this test is simply wrong. Similarly:
{{{
sage: edit(Q.gen,'vim')
sage: def check_old_coerce(p):
....: if p._element_constructor is not None:
....: raise RuntimeError, "%s still using old coercion framework"
% p
....:
sage: check_old_coerce(QQ[['x']])
Traceback (most recent call last):
...
RuntimeError: Power Series Ring in x over Rational Field still using old
coercion framework
sage: check_old_coerce(SymmetricFunctionAlgebra(QQ))
Traceback (most recent call last)
...
RuntimeError: Symmetric Functions over Rational Field in the Schur basis
still using old coercion framework
}}}
I think it is time to remove this test. But not on this ticket, of course.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11490#comment:44>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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