Lint: Enable RUF012 and annotate mutable class attributes with ClassVar (mesa#3033)

falloficaruss · pre-commit-ci[bot] · quaquel · web-flow · commit 83d268a68fd1 · 2026-01-06T20:58:48.000+01:00
* Enable RUF012 and fix mutable class attribute annotations - Enable RUF012 in ruff configuration. - Annotate mutable class attributes with ClassVar in core code and tests. - Affected files: mesa/agent.py, mesa/discrete_space/cell_agent.py, mesa/mesa_logging.py, pd_grid model, and visualization tests. * [pre-commit.ci] auto fixes from pre-commit.com hooks for more information, see https://pre-commit.ci --------- Co-authored-by: Abhishek Shinde <139879930+TheRuminated@users.noreply.github.com> Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com> Co-authored-by: Jan Kwakkel <j.h.kwakkel@tudelft.nl>
diff --git a/mesa/agent.py b/mesa/agent.py
@@ -18,7 +18,7 @@
 from random import Random
 
 # mypy
-from typing import TYPE_CHECKING, Any, Literal, overload
+from typing import TYPE_CHECKING, Any, ClassVar, Literal, overload
 
 import numpy as np
 
@@ -45,7 +45,7 @@ class Agent:
     # this is a class level attribute
     # it is a dictionary, indexed by model instance
     # so, unique_id is unique relative to a model, and counting starts from 1
-    _ids = defaultdict(functools.partial(itertools.count, 1))
+    _ids: ClassVar[defaultdict] = defaultdict(functools.partial(itertools.count, 1))
 
     def __init__(self, model: Model, *args, **kwargs) -> None:
         """Create a new agent.
diff --git a/mesa/discrete_space/cell_agent.py b/mesa/discrete_space/cell_agent.py
@@ -13,7 +13,7 @@
 
 from __future__ import annotations
 
-from typing import TYPE_CHECKING, Protocol
+from typing import TYPE_CHECKING, ClassVar, Protocol
 
 from mesa.agent import Agent
 
@@ -115,7 +115,7 @@ class Grid2DMovingAgent(CellAgent):
     """Mixin for moving agents in 2D grids."""
 
     # fmt: off
-    DIRECTION_MAP = {
+    DIRECTION_MAP: ClassVar[dict[str, tuple[int, int]]] = {
         "n": (-1, 0), "north": (-1, 0), "up": (-1, 0),
         "s": (1, 0), "south": (1, 0), "down": (1, 0),
         "e": (0, 1), "east": (0, 1), "right": (0, 1),
diff --git a/mesa/examples/advanced/pd_grid/model.py b/mesa/examples/advanced/pd_grid/model.py
@@ -1,3 +1,5 @@
+import typing
+
 import mesa
 from mesa.discrete_space import OrthogonalMooreGrid
 from mesa.examples.advanced.pd_grid.agents import PDAgent
@@ -6,12 +8,21 @@
 class PdGrid(mesa.Model):
     """Model class for iterated, spatial prisoner's dilemma model."""
 
-    activation_regimes = ["Sequential", "Random", "Simultaneous"]
+    activation_regimes: typing.ClassVar[list[str]] = [
+        "Sequential",
+        "Random",
+        "Simultaneous",
+    ]
 
     # This dictionary holds the payoff for this agent,
     # keyed on: (my_move, other_move)
 
-    payoff = {("C", "C"): 1, ("C", "D"): 0, ("D", "C"): 1.6, ("D", "D"): 0}
+    payoff: typing.ClassVar[dict[tuple[str, str], float]] = {
+        ("C", "C"): 1,
+        ("C", "D"): 0,
+        ("D", "C"): 1.6,
+        ("D", "D"): 0,
+    }
 
     def __init__(
         self, width=50, height=50, activation_order="Random", payoffs=None, seed=None
diff --git a/mesa/mesa_logging.py b/mesa/mesa_logging.py
@@ -9,6 +9,7 @@
 import logging
 from functools import wraps
 from logging import DEBUG, INFO
+from typing import ClassVar
 
 __all__ = [
     "DEBUG",
@@ -75,7 +76,7 @@ class MESAColorFormatter(logging.Formatter):
         "[%(asctime)s] [%(name)s] [%(levelname)s] %(message)s [%(filename)s:%(lineno)d]"
     )
 
-    FORMATS = {
+    FORMATS: ClassVar[dict[int, str]] = {
         logging.DEBUG: grey + format + reset,
         logging.INFO: green + format + reset,
         logging.WARNING: yellow + format + reset,
diff --git a/pyproject.toml b/pyproject.toml
@@ -163,7 +163,6 @@ extend-ignore = [
   "B905",   # `zip()` without an explicit `strict=` parameter
   "N802",   # Function name should be lowercase
   "N999",   # Invalid module name. We should revisit this in the future, TODO
-  "RUF012", # Mutable class attributes should be annotated with `typing.ClassVar` TODO
   "S310",   # Audit URL open for permitted schemes. Allowing use of `file:` or custom schemes is often unexpected.
   "S603",   # `subprocess` call: check for execution of untrusted input
   "ISC001", # ruff format asks to disable this feature
diff --git a/tests/visualization/test_backends.py b/tests/visualization/test_backends.py
@@ -2,6 +2,7 @@
 
 import random
 import types
+from typing import ClassVar
 from unittest.mock import MagicMock
 
 import numpy as np
@@ -49,7 +50,7 @@ class DummyAgent:
         cell = types.SimpleNamespace(coordinate=(0, 0))
 
     class DummySpace:
-        agents = [DummyAgent()]
+        agents: ClassVar[list] = [DummyAgent()]
 
     # Test with AgentPortrayalStyle
     def agent_portrayal_style(agent):
@@ -187,7 +188,7 @@ class DummyAgent:
         cell = types.SimpleNamespace(coordinate=(0, 0))
 
     class DummySpace:
-        agents = [DummyAgent()]
+        agents: ClassVar[list] = [DummyAgent()]
 
     # Test with AgentPortrayalStyle
     def agent_portrayal_style(agent):
@@ -225,7 +226,7 @@ class DummyAgent:
         cell = types.SimpleNamespace(coordinate=(0, 0))
 
     class DummySpace:
-        agents = [DummyAgent()]
+        agents: ClassVar[list] = [DummyAgent()]
 
     def agent_portrayal(agent):
         return AgentPortrayalStyle(
