mymemoryview.py

class MyMemoryview:
    def __init__(self, mv):
        self._mv = memoryview(mv)

    def __getitem__(self, i):
        value = self._mv.__getitem__(i)
        if isinstance(value, memoryview):
            return MyMemoryview(value)
        return value

    def __setitem__(self, i, value):
        return self._mv.__setitem__(i, value)

    def __getattribute__(self, attr):
        whitelist = ('__class__', '_mv')
        if attr in whitelist:
            return object.__getattribute__(self, attr)
        
        value = getattr(object.__getattribute__(self, '_mv'), attr)
        if callable(value):
            def wrapper(*args, **kwargs):
                result = value(*args, **kwargs)
                if isinstance(result, memoryview):
                    return type(self)(result)
                return result
            return wrapper
        return value


mmv = MyMemoryview(b'1234567890')
assert isinstance(mmv[2:4], MyMemoryview)