What are the differences between type() and isinstance()?

Question

What are the differences between these two code fragments?

Using type():

import types

if type(a) is types.DictType:
    do_something(         


        

Answer 1

The latter is preferred, because it will handle subclasses properly. In fact, your example can be written even more easily because isinstance()'s second parameter may be a tuple:

if isinstance(b, (str, unicode)):
    do_something_else()

or, using the basestring abstract class:

if isinstance(b, basestring):
    do_something_else()