Type of compiled regex object in python

Question

What is the type of the compiled regular expression in python?

In particular, I want to evaluate

isinstance(re.compile(\'\'), ???)

Answer 1

Python 3.5 introduced the typing module. Included therein is typing.Pattern, a _TypeAlias.

Starting with Python 3.6, you can simply do:

from typing import Pattern

my_re = re.compile('foo')
assert isinstance(my_re, Pattern)

In 3.5, there used to be a bug requiring you to do this:

assert issubclass(type(my_re), Pattern)

Which isn’t guaranteed to work according to the documentation and test suite.