Getting the class name of an instance?

Question

How do I find out a name of class that created an instance of an object in Python if the function I am doing this from is the base class of which the class of the instance h

Answer 1

type() ?

>>> class A(object):
...    def whoami(self):
...       print type(self).__name__
...
>>>
>>> class B(A):
...    pass
...
>>>
>>>
>>> o = B()
>>> o.whoami()
'B'
>>>

Answer 2

Apart from grabbing the special __name__ attribute, you might find yourself in need of the qualified name for a given class/function. This is done by grabbing the types __qualname__.

In most cases, these will be exactly the same, but, when dealing with nested classes/methods these differ in the output you get. For example:

class Spam:
    def meth(self):
        pass
    class Bar:
        pass

>>> s = Spam()
>>> type(s).__name__ 
'Spam'
>>> type(s).__qualname__
'Spam'
>>> type(s).Bar.__name__       # type not needed here
'Bar'
>>> type(s).Bar.__qualname__   # type not needed here 
'Spam.Bar'
>>> type(s).meth.__name__
'meth'
>>> type(s).meth.__qualname__
'Spam.meth'

Since introspection is what you're after, this is always you might want to consider.

Answer 3

class A:
  pass

a = A()
str(a.__class__)

The sample code above (when input in the interactive interpreter) will produce '__main__.A' as opposed to 'A' which is produced if the __name__ attribute is invoked. By simply passing the result of A.__class__ to the str constructor the parsing is handled for you. However, you could also use the following code if you want something more explicit.

"{0}.{1}".format(a.__class__.__module__,a.__class__.__name__)

This behavior can be preferable if you have classes with the same name defined in separate modules.

The sample code provided above was tested in Python 2.7.5.

Answer 4

Have you tried the __name__ attribute of the class? ie type(x).__name__ will give you the name of the class, which I think is what you want.

>>> import itertools
>>> x = itertools.count(0)
>>> type(x).__name__
'count'

If you're still using Python 2, note that the above method works with new-style classes only (in Python 3+ all classes are "new-style" classes). Your code might use some old-style classes. The following works for both:

x.__class__.__name__

Answer 5

Do you want the name of the class as a string?

instance.__class__.__name__

Answer 6

Good question.

Here's a simple example based on GHZ's which might help someone:

>>> class person(object):
        def init(self,name):
            self.name=name
        def info(self)
            print "My name is {0}, I am a {1}".format(self.name,self.__class__.__name__)
>>> bob = person(name='Robert')
>>> bob.info()
My name is Robert, I am a person