using setattr within a class method to sel something on self

Question

When doing this

class Example:
    def __init__(self, a, b):
        self.a = a
        self.b = b

    def update(self, **kwargs):
        for key, value in kwargs.items():
            getattr(self, key)
            setattr(self, key, value)

.. the update function won't update an instance of this class. I've tried self.__setattr__(key, value) and object.__setattr__(self, key, value) and even tried eval(f"self.{key}={repr(value)}") which threw an error!

UPDATE: The code does work.initially I had coded self.__setattr__(key, value). Microsoft vscode ( running on linux ) somehow caches things, for a very very long time and despite rotating through several changes of code didn't show any change in the test results i was running. After taking a break to ask this question I ran the answer code below, then reverted to setattr and everything worked from there. really annoyed with that!!

Answer 1

Use __dict__ as a shortcut:

class Example:
    def __init__(self, a, b):
        self.a = a
        self.b = b

    def update(self, **kwargs):
        # you need to do some checks here (if attribute exists or not)
        self.__dict__.update(kwargs)


e = Example(1, 2)
print(e.__dict__)

e.update(a=3, b=4)
print(e.__dict__)

Output:

{'a': 1, 'b': 2}
{'a': 3, 'b': 4}