The top answer for Class method decorator with self arguments? (direct link to answer: https://stackoverflow.com/a/11731208) describes how a decorator can access attributes of the object when decorating a method.
I tried to apply this to my own code, but realized it only works when using a function as the decorator. For some reason, when using a class as the decorator, the arguments tuple no longer contains the self object. Why does this happen, and is there some other way to access the wrapped method's self?
To demonstrate:
import functools class DecoratorClass: def __init__(self, func): functools.update_wrapper(self, func) self.func = func def __call__(self, *args, **kwargs): print("args:", args) print("kwargs:", kwargs) print("Counting with:", args[0].name) self.func(*args, **kwargs) def decorator_func(func): @functools.wraps(func) def wrapper(*args, **kwargs): print("args:", args) print("kwargs:", kwargs) print("Counting with:", args[0].name) func(*args, **kwargs) return wrapper class Counter: def __init__(self, name, count): self.name = name self.count = count @decorator_func def count_a(self): for i in range(self.count): print(i) @DecoratorClass def count_b(self): for i in range(self.count): print(i) c = Counter('my counter', 3) c.count_a() print() c.count_b() Output:
args: (<__main__.Counter object at 0x7f4491a21970>,) kwargs: {} Counting with: my counter 0 1 2 args: () kwargs: {} Traceback (most recent call last): File "./test2.py", line 48, in <module> c.count_b() File "./test2.py", line 14, in __call__ print("Counting with:", args[0].name) IndexError: tuple index out of range 
