Best way to do a "not None" test in Python for a normal and Unicode empty string?

Question

In Python 2.7, I'm writing a class that calls a function in an API which might, or might not, return an empty string. Furthermore, the empty string might be unicode u"", or non-unicode "". I was wondering what the best way to check for this?

The following code works great for an empty string, but not an empty unicode string:

class FooClass():     string = ...     string = might_return_normal_empty_string_or_unicode_empty_string(string)      # Works for normal empty strings, not unicode:     if string is not None:         print "string is not an empty string." 

Instead I'd have to write it like this to get it to work for unicode:

class BarClass():     string = ...     string = might_return_normal_empty_string_or_unicode_empty_string(string)      # Works for unicode empty strings, not normal:     if string is not u"":         print "string is not an empty string." 

...and like this to get it to work for both empty strings in non-unicode and unicode:

class FooBarClass():     string = ...     string = might_return_normal_empty_string_or_unicode_empty_string(string)      # Works for both normal and unicode empty strings:     if string is not u"" or None:         print "string is not an empty string." 

Is the third method the best way to do this, or is there a better way? I ask because writing a u"" feels a little too hard-coded to me. But if that's the best way to do it, so be it. :) Thanks for any help you can offer.

Answer 1

Empty strings are considered false.

if string:     # String is not empty. else:     # String is empty.