Question

import string
print string.ascii_lowercase # abcdefghijklmnopqrstuvwxyz
print type(string.ascii_lowercase) # <type 'str'>
print string.ascii_lowercase is str # False

Shouldn’t it be True?

Answer 1

The is operator compares the identity of two objects. This is what I believe it does behind the scenes:

id(string.ascii_lowercase) == id(str)

Actual strings are always going to have a different identity than the type str, so this will always be False.

Here is the most Pythonic way to test whether something is a string:

isinstance(string.ascii_lowercase, basestring)

This will match both str and unicode strings.