BUG: ufunc.__call__ treats out passed by position and keyword differently #10450
Description
Extracted from #10382, which this is partly the cause of.
Using this simple class to debug:
class MyArray(np.ndarray):
def __array_wrap__(self, obj, context=None):
print('__array_wrap__ ({}, {}, {})'.format(self, obj,context))
return self
def __array_prepare__(self, obj, context=None):
print('__array_prepare__({}, {}, {})'.format(self, obj,context))
return self
a = np.zeros((), int).view(MyArray)we have:
# all ok
>>> np.add(-1, 1, a)
__array_prepare__(0, 0, (<ufunc 'add'>, (-1, 1, MyArray(0)), 0))
__array_wrap__ (0, 0, (<ufunc 'add'>, (-1, 1, MyArray(0)), 0))
# no out argument to __array_wrap__
>>> np.add(-1, 1, out=a)
__array_prepare__(0, 0, (<ufunc 'add'>, (-1, 1, MyArray(0)), 0))
__array_wrap__ (0, 0, (<ufunc 'add'>, (-1, 1), 0))
# where did __array_prepare__ go?
>>> np.add(-1, 1, out=(a,))
__array_wrap__ (0, 0, (<ufunc 'add'>, (-1, 1), 0))and with an input
#ok
>>> np.add(0, a, a)
__array_prepare__(0, 0, (<ufunc 'add'>, (0, MyArray(0), MyArray(0)), 0))
__array_wrap__ (0, 0, (<ufunc 'add'>, (0, MyArray(0), MyArray(0)), 0))
# no out argument to __array_wrap__
>>> np.add(0, a, out=a)
__array_prepare__(0, 0, (<ufunc 'add'>, (0, MyArray(0), MyArray(0)), 0))
__array_wrap__ (0, 0, (<ufunc 'add'>, (0, MyArray(0)), 0))
# holy tuple batman
>>> np.add(0, a, out=(a,))
__array_prepare__(0, 0, (<ufunc 'add'>, (0, MyArray(0), (MyArray(0),)), 0))
__array_wrap__ (0, 0, (<ufunc 'add'>, (0, MyArray(0)), 0))I can see a few other places where this bug might exist too - anything passing args in PyUfunc_GenericFunction` may be guilty. I think we need to fix this at the earliest possible location, and convert positional to keyword arguments as soon as possible.