How to check if the string is empty?

Question

Does Python have something like an empty string variable where you can do:

if myString == string.empty:

Regardless, what\'s the most elegan

Answer 1

Responding to @1290. Sorry, no way to format blocks in comments. The None value is not an empty string in Python, and neither is (spaces). The answer from Andrew Clark is the correct one: if not myString. The answer from @rouble is application-specific and does not answer the OP's question. You will get in trouble if you adopt a peculiar definition of what is a "blank" string. In particular, the standard behavior is that str(None) produces 'None', a non-blank string.

However if you must treat None and (spaces) as "blank" strings, here is a better way:

class weirdstr(str):
    def __new__(cls, content):
        return str.__new__(cls, content if content is not None else '')
    def __nonzero__(self):
        return bool(self.strip())

Examples:

>>> normal = weirdstr('word')
>>> print normal, bool(normal)
word True

>>> spaces = weirdstr('   ')
>>> print spaces, bool(spaces)
    False

>>> blank = weirdstr('')
>>> print blank, bool(blank)
 False

>>> none = weirdstr(None)
>>> print none, bool(none)
 False

>>> if not spaces:
...     print 'This is a so-called blank string'
... 
This is a so-called blank string

Meets the @rouble requirements while not breaking the expected bool behavior of strings.