Superclass of bytes and bytearray?

Question

I'm making a function which will accept either an Unicode string or a bytes (or bytearray) object. I want to make sure only those types get passed. I know I can check whether something is a string by doing isinstance(x, str), and I know I can write isinstance(x, bytes) or isinstance(x, bytearray).

Is there a more concise way to check the latter, i.e., is there a class from which both bytes and bytearray derive?

Answer 1

There is no common base class except for object:

>>> bytearray.__base__
<class 'object'>
>>> bytes.__base__
<class 'object'>

Don't check for the type. Let the user pass parameters of whatever type she desires. If the type does not have the required interface, your code will fail anyway.

Answer 2

You can use:

isinstance(x, (bytes, bytearray))

However, duck typing might be useful, so other types not deriving from bytes or bytearray, but implementing the right methods could be passed to the function.