Mark Dickinson <dicki...@gmail.com> added the comment:
> Maybe use PyNumber_Check() [...]
Ah, that works. It reads better than the `PyFloat_AsDouble` solution, too,
since it's far from obvious that `PyFloat_AsDouble` goes to the trouble to
coerce a float-y thing to a float.
I did some searching around to see if I could find evidence that anyone besides
me thinks this is a good idea, but I didn't come up with much. In the NumPy
source, for example, it's more common to want a C `double` than another Python
object, and I guess that's going to be true for other 3rd party libraries, too.
And I'm also realising that part of what I need here is a *Python*-level
solution to the problem, something like this:
def _validate_float(value):
"""
Coerce an arbitrary Python object to a float, or raise TypeError.
"""
if type(value) is float: # fast path for common case
return value
try:
nb_float = type(value).__float__
except AttributeError:
raise TypeError(
"Object of type {!r} not coerceable to float".format(type(value)))
return nb_float(value)
(and the _validate_float I posted earlier was really just there because the C
extension module needed to be able to do the same thing as the equivalent
Python code above).
All in all, I don't think I can make a good case for this. I'll close the issue.
----------
resolution: -> rejected
stage: -> resolved
status: open -> closed
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Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue32794>
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