How do I check if a python function changed (in live code)?

Question

If I have a reference to a function I can check it\'s code object f.__code__, get a signature, then perform later checks against this signature to see if the code c

Answer 1

You may to compare bytecode attributes on code object using method.__code__.co_code. For example lets define two classes:

>>> class A:
...     a = 1
...     def b(self, b):
...             print(self.a + b)
... 
>>> class B:
...     a = 1
...     def b(self, b):
...             print(self.a + b)
... 
>>> A().b.__code__.co_code
'|\x00\x00j\x00\x00|\x01\x00\x17GHd\x00\x00S'
>>> B().b.__code__.co_code
'|\x00\x00j\x00\x00|\x01\x00\x17GHd\x00\x00S'
>>> A().b.__code__.co_code == B().b.__code__.co_code
True

and if method b in class A is changed:

>>> class A:
...     a = 1
...     def b(self, b):
...             print(b + self.a)
... 
>>> A().b.__code__.co_code
'|\x01\x00|\x00\x00j\x00\x00\x17GHd\x00\x00S'
>>> A().b.__code__.co_code == B().b.__code__.co_code
False

or use inspect method inspect.getsource(object) that:

Return the text of the source code for an object. The argument may be a module, class, method, function, traceback, frame, or code object. The source code is returned as a single string.

And if you want to know whether the code has changed in dynamic you may need to reload your class with importlib and compare bytecode.