Two years ago I suggested this:

> Then I would prefer a view, using e.g. the buffer API, but without any copies.

... and of course Numpy already provides such an API:

>>> a, b = b"123", bytearray(b"abc")
>>> p = np.frombuffer(a, dtype=np.int8)
>>> q = np.frombuffer(b, dtype=np.int8)
>>> p ^ q
array([80, 80, 80], dtype=int8)
>>> b[0] = 64
>>> p ^ q
array([113,  80,  80], dtype=int8)