#17547: BuiltinFunction overriding GiNaC function is allowed
-----------------------------+------------------------
Reporter: rws | Owner:
Type: defect | Status: new
Priority: major | Milestone: sage-6.5
Component: symbolics | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Old description:
> {{{
> sage: from sage.symbolic.function import BuiltinFunction
> sage: class AFunction(BuiltinFunction):
> ....: def __init__(self, name, exp=1):
> ....: self.exponent=exp
> ....: BuiltinFunction.__init__(self, name, nargs=1)
> ....: def _eval_(self, arg):
> ....: return arg**self.exponent
> sage: p2 = AFunction('exp', 2)
> sage: p2(x)
> e^x
> }}}
> The attempt at creation should give an error (plus respective
> documentation warnings).
>
> Alternatively, search first for user-defined function names, then GiNaC
> core, to allow overriding.
New description:
{{{
sage: from sage.symbolic.function import BuiltinFunction
sage: class AFunction(BuiltinFunction):
....: def __init__(self, name, exp=1):
....: self.exponent=exp
....: BuiltinFunction.__init__(self, name, nargs=1)
....: def _eval_(self, arg):
....: return arg**self.exponent
sage: p2 = AFunction('exp', 2)
sage: p2(x)
e^x
}}}
If the name is e.g. `p2` `AFunction.eval` gets called, but not with name
equal to a function provided with GiNaC. Compare the above with
{{{
...
sage: p2 = AFunction('p2', 2)
sage: p2(x)
x^2
}}}
The attempt at creation should give an error (plus respective
documentation warnings).
Alternatively, search first for user-defined function names, then GiNaC
core, to allow overriding.
--
Comment (by rws):
If the name is e.g. `p2` `AFunction.eval` gets called, but not with name
equal to a function provided with GiNaC. Compare the above with
{{{
...
sage: p2 = AFunction('p2', 2)
sage: p2(x)
x^2
}}}
--
Ticket URL: <http://trac.sagemath.org/ticket/17547#comment:4>
Sage <http://www.sagemath.org>
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