Assignments to class attributes inside `__init__()` are not inferred

[bje-]

Bug description

Pylint produces an incorrect unsubscriptable-object warning.

"""A test case."""
import numpy as np

class Foo:
    """Class docstring."""

    csvfilename = None
    csvdata = None

    def __init__(self, filename):
        cls = self.__class__
        assert filename is not None
        if cls.csvfilename != filename:
            cls.csvdata = np.zeros(10)
            cls.csvfilenanme = filename
        self.generation = cls.csvdata[0]

Command used

pylint testcase.py

Pylint output

************* Module testcase
testcase.py:16:26: E1136: Value 'cls.csvdata' is unsubscriptable (unsubscriptable-object)

Expected behavior

No warning should be emitted.

Pylint version

pylint 3.0.2
astroid 3.0.1
Python 3.10.12 (main, Jun 11 2023, 05:26:28) [GCC 11.4.0]

OS / Environment

Ubuntu 22.04

[jacobtylerwalls]

Thanks for the report. pylint/astroid currently doesn't understand dynamic assignment to class attributes, like cls.csvdata = .... We just know that cls.csvdata is None from the earlier assignment.

[jacobtylerwalls]

Sorry, here's the correct demo:

>>> node = astroid.extract_node("""
... class MyClass:
...     attr = None
...     def __init__(self):
...         cls = self.__class__
...         cls.attr = 1
...         cls.attr #@
... """)
>>> node.inferred()
[<Const.NoneType l.3 at 0x1084e2ea0>]

[jacobtylerwalls]

Actually, the warning is correct if the equality if cls.csvfilename != filename fails, but I take your point.