store_attr: does not update instance variable

[thatgeeman]

Hi! Thanks for this wonderful library. Reporting a scenario where store_attr does not behave the way I want it to:

# case 1: works
class T:
    def __init__(self, a, b, c):
        store_attr() 
    def __repr__(self):
        return f'T({self.__stored_args__})'

# case 2: fails
class T_:
    def __init__(self, a, b, c):
        self.a = a - 1  # modify variable a
        store_attr()
    def __repr__(self):
        return f'T({self.__stored_args__})'
        
T(1, 2, 3), T_(1, 2, 3)
# (T({'a': 1, 'b': 2, 'c': 3}), T_({'a': 1, 'b': 2, 'c': 3}))

In the second case, I would've expected T_.a to store the updated attribute, but this is not the case. Is this not the intended use case (to store all attributes) or is it supposed to be used only to store the args passed to instantiate the class?
Cheers,

[erikgaas]

PR #710 fixes this by checking if an attribute already exists on self before storing. Uses getattr(self, n, fr.f_locals[n]) to prefer existing values over the original arguments.

[jph00]

Thanks for the interesting issue, and @erikgaas nice clean implementation. For me, though, I feel like this behavior is a bit surprising. I'd expect store_attr to store the attrs! If you want to set them to something else, I just put the store_attr call earlier than the lines that override it.

Are there situations where the current behavior doesn't work out, by reordering your code like this?

[erikgaas]

@jph00 Sounds good I agree. I think we can close this issue and the PR.