__qualname__ emulation for older Python versions
Project description
Python module to emulate the __qualname__ attribute for classes and methods (Python 3.3+) in older Python versions. See PEP 3155 for details.
Installation
pip install qualname
Usage
Assume these definitions:
class C:
def f():
pass
class D:
def g():
pass
In Python 3.3+, classes have a __qualname__ property:
>>> C.__qualname__ 'C' >>> C.f.__qualname__ 'C.f' >>> C.D.__qualname__ 'C.D' >>> C.D.g.__qualname__ 'C.D.g'
Unfortunately, Python 2 and early Python 3 versions do not have an (obvious) equivalent. qualname to the rescue:
from qualname import qualname >>> qualname(C) 'C' >>> qualname(C.f) 'C.f' >>> qualname(C.D) 'C.D' >>> qualname(C.D.g) 'C.D.g'
Victory!
How does it work?
Glad you ask.
This module uses source code inspection to figure out how (nested) classes and functions are defined in order to determine the qualified name for it. That means parsing the source file, and traversing the AST (abstract syntax tree). This sounds very hacky, and it is, but the Python interpreter itself does not have the necessary information, so this justifies extreme measures.
Now that you know how it works, you’ll also understand that this module only works when the source file is available. Fortunately this is the case in most circumstances.
License
BSD.
