in-place exponentiation incongruities

[Giacomo Alzetta]

I've noticed some incongruities regarding in-place exponentiation.

On the C side nb_inplace_power is a ternary function, like nb_power (see here: http://docs.python.org/c-api/typeobj.html?highlight=numbermethods#PyNumberMethods).

Obviously you can't pass the third argument using the usual in-place syntax "**=".
Nevertheless I'd expect to be able to provide the third argument using operator.ipow. But the operator module accept only the two parameter variant.

The Number Protocol specify that the ipow operation ""is the equivalent of the Python statement o1 **= o2 when o3 is Py_None, or an in-place variant of pow(o1, o2, o3) otherwise.""

Since "operator" claims to be contain a "function port" of the operators, I'd expect it to implement ipow with three arguments.
I don't see any problem in adding the third argument to it(I mean, sure right now any code that calls ipow(a,b,c) [if exists] is broken, because it will just raise a TypeError, thus adding the argument will not break any code, and would provide more functionality.

Also, I don't think there are many objects in the build-ins or standardlib which implement an in-place exponentiation, so this means there wont be much code to change.

So my question is: why are there this incongruities?
Is there any chance to see this fixed? (in the operator module, or changing the documentation)

By the way: I'm asking this because I'm implementing a C-extension and I'd like to implement both pow and ipow. And since it's about polynomials on (Z/nZ)[x]/x^r-1, using the third argument always makes sense.