What is __qualname__ in python?

Question

• What is __qualname__ in python and how is it useful?

• Why would I need to use it over __name__?

I read the docs, but they didn't help me get a clear understanding on it's usefulness.

I have read Get fully qualified name of a Python class (Python 3.3+).
That question asks "how to get a qualified name", which presumes that one knows the meaning of "qualified name". Obviously, the answer to that question is to use the __qualname__ attribute.

My question asks what __qualname__ is, and why should I use it over __name__.

Answer 1

__qualname__ gives more complete information than __name__ and therefore can be more helpful in debugging, for example.

Example:

>>> def f(): pass ... class A: ...    def f(self): pass ...    class A: ...        def f(self): pass ... >>> # __name__ is not showing the path, so these functions look equal >>> f.__name__ 'f' >>> A.f.__name__ 'f' >>> A.A.f.__name__ 'f' >>> # And these classes looks equal >>> A.__name__ 'A' >>> A.A.__name__ 'A' >>> >>> # __qualname__ shows the path, so these functions are distinguishable >>> f.__qualname__ 'f' >>> A.f.__qualname__ 'A.f' >>> A.A.f.__qualname__ 'A.A.f' >>> # And these classes are distinguishable >>> A.__qualname__ 'A' >>> A.A.__qualname__ 'A.A' 

__qualname__ is also adding some backwards compatibility with Python 2's .im_class.

More details in the rationale for PEP 3155