Development Bug: pyright and other language servers cannot identify unresolved references on subclasses of StateMachine

[comalice]

• Python State Machine version: 2.5.0
• Python version: 3.12
• Operating System: Windows 11

Description

As in the title, when StateMachine is subclassed, no unresolved references are found by pyright or similar language servers.

What I Did

In the following example code, the class without inheritance is flagged correctly as having an unresolved reference. The class with inheritance is not flagged correctly.

from statemachine import StateMachine


class MyStatemachine(StateMachine):
    def __init__(self):
        super().__init__()
        self.this_method_does_not_exist()

class MyNotStatemachine:
    def __init__(self):
        self.this_method_does_not_exist()

[comalice]

And resolution of functions not in the subclass are correctly analyzed:

from statemachine import StateMachine


def a_function_from_an_outer_scope():
    return True


class MyStatemachine(StateMachine):
    def __init__(self):
        super().__init__()
        self.this_method_does_not_exist()
        this_method_also_does_not_exist()
        a_function_from_an_outer_scope()


class MyNotStatemachine:
    def __init__(self):
        self.this_method_does_not_exist()
        this_method_also_does_not_exist()
        a_function_from_an_outer_scope()

[fgmacedo]

Hi @comalice , thanks for reporting this!

I think that this is the source of this issue:

python-statemachine/statemachine/statemachine.py

Lines 118 to 121 in 9954890

	if TYPE_CHECKING:
	"""Makes mypy happy with dynamic created attributes"""
	def __getattr__(self, attribute: str) -> Any: ...

It was added to make mypy stop complaining about dynamic-created state machine attributes.

We need to figure out another and better way, or I will forever be trapped between choosing which linter error is displayed :(

[comalice]

I'll see if I can poke around and figure something out. There are mypy stub generators (used on peewee, for example) that might be useful here.