Get fully qualified class name of an object in Python

The provided answers don't deal with nested classes.

Since Python 3.3 (PEP 3155), you can use __qualname__ of the class instead of the __name__. Otherwise, a class like

class Foo:
    class Bar: # this one
        pass

will show up as just Bar instead of Foo.Bar.

(You'll still need to attach the __module__ to the qualname separately - __qualname__ is not intended to include module names.)

With the following program

#!/usr/bin/env python

import foo

def fullname(o):
    klass = o.__class__
    module = klass.__module__
    if module == 'builtins':
        return klass.__qualname__ # avoid outputs like 'builtins.str'
    return module + '.' + klass.__qualname__

bar = foo.Bar()
print(fullname(bar))

and Bar defined as

class Bar(object):
  def __init__(self, v=42):
    self.val = v

the output is

$ ./prog.py
foo.Bar

If you're still stuck on Python 2, you'll have to use __name__ instead of __qualname__, which is less informative for nested classes - a class Bar nested in a class Foo will show up as Bar instead of Foo.Bar:

def fullname(o):
    klass = o.__class__
    module = klass.__module__
    if module == '__builtin__':
        return klass.__name__ # avoid outputs like '__builtin__.str'
    return module + '.' + klass.__name__