False positive unnecessary-dunder-call for __iadd__ about pylint HOT 4 OPEN

What about adding the __add__ function directly in Incrementable ?

"""https://github.com/pylint-dev/pylint/issues/8978"""

class Incrementable:
    """class with an incrementable field"""
    def __init__(self, a):
        self.a = a

    def __add__(self, other):
        return self.__iadd__(other)

    def __iadd__(self, other):
        if isinstance(other, Incrementable):
            self.a += other.a
            return self
        return NotImplemented

d = {}
d.setdefault("a", Incrementable(6) + Incrementable(7))

from pylint.

Following the suggestion given by the warning results in code that fails to parse:

d.setdefault("a", Incrementable(6)) += Incrementable(7)  # Use += operator

E0001: Parsing failed: ''function call' is an illegal expression for augmented assignment (<unknown>, line 14)' (syntax-error)

from pylint.

Yes, but I think the message should be modified and still raised (in order to make the code more pythonic like in my proposed snippet). Something like 'create an __add__ method in 'Increment' and use it'

from pylint.

What about adding the __add__ function directly in Incrementable ?

"""https://github.com/pylint-dev/pylint/issues/8978"""

class Incrementable:
    """class with an incrementable field"""
    def __init__(self, a):
        self.a = a

    def __add__(self, other):
        return self.__iadd__(other)

    def __iadd__(self, other):
        if isinstance(other, Incrementable):
            self.a += other.a
            return self
        return NotImplemented

d = {}
d.setdefault("a", Incrementable(6) + Incrementable(7))

this does not modify d["a"] if it is already present, i.e.

d = {"a":Incrementable(2)}
d.setdefault("a", Incrementable(6) + Incrementable(7))

is not the same as

d = {"a":Incrementable(2)}
d.setdefault("a", Incrementable(6)).__iadd__(Incrementable(7))

IOW, this code is NOT equivalent to the code that I posted in all cases.

from pylint.