#6245: make a custom infix operator decorator
-------------------------------------------------------+--------------------
Reporter: jason | Owner: cwitty
Type: enhancement | Status:
needs_review
Priority: major | Milestone: sage-4.4
Component: misc | Keywords:
Author: Jason Grout, Carl Witty, Florent Hivert | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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Comment(by jason):
Replying to [comment:14 rossk]:
> Noticed references to {{{__rmul__}}} in the code so I thought I might
try setting up a situation[[BR]]
>
> where {{{__mul__}}} fails so {{{__rmul__}}} would be exercised. In
setting up the test code, I got an[[BR]]
>
> error but cant see whats wrong (any thoughts?)
The problem is that your __mul__ function does not check its arguments.
Note that:
{{{
sage: Fraction(2,3)*matrix(2,1,[1,2])
Traceback (click to the left of this block for traceback)
...
AttributeError: 'sage.matrix.matrix_integer_dense.Matrix_integer_dense'
object has no attribute 'numerator'
}}}
Instead, you should check your arguments in the __mul__ function before
blindly calling the .numerator method, or at least you should catch the
error, like this:
{{{
class Fraction:
def __init__(self, numerator, denominator=1):
self.numerator = numerator
self.denominator = denominator
def __str__(self):
return "Fraction(%d,%d)" % (self.numerator, self.denominator)
__repr__=__str__
def zmul(self, other):
return Fraction(self.numerator*other.numerator,
self.denominator*other.denominator)
def __mul__(self, other):
try:
return Fraction(self.numerator*other.numerator,
self.denominator*other.denominator)
except:
return NotImplemented
}}}
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/6245#comment:15>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
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