Compare string to bytes that works in both Python 2 and 3

Question

What is the best way to compare a string object to a bytes object that works in both Python 2 and Python 3? Assume both are UTF-8. More generally, how does one write a Python 2 and Python 3 compatible comparison of two objects that may each be a string, bytes, or Unicode object?

The problem is that "asdf" == b"asdf" is True in Python 2 and False in Python 3.

Meanwhile, one cannot blindly encode or decode objects, since strings in Python 2 have both encode and decode methods, but strings in Python 3 just have encode methods.

Finally, isinstance(obj, bytes) returns True for any non-unicode string in Python 2 and returns True for only bytes objects in Python 3.

Answer 1

In both Python 2 and Python 3, anything that is an instance of bytes has a decode method. Thus, you can do the following:

def compare(a, b, encoding="utf8"):
    if isinstance(a, bytes):
        a = a.decode(encoding)
    if isinstance(b, bytes):
        b = b.decode(encoding)
    return a == b