fix: Regression that causes an exception when registering listeners with unbounded callables. (#466)

Author: fgmacedo

docs/releases/2.3.4.md

@@ -0,0 +1,8 @@
+# StateMachine 2.3.4
+
+*July 11, 2024*
+
+
+## Bugfixes in 2.3.4
+
+- Fixes [#465](https://github.com/fgmacedo/python-statemachine/issues/465) regression that caused exception when registering a listener with unbounded callbacks.

docs/releases/index.md

@@ -15,6 +15,7 @@ Below are release notes through StateMachine and its patch releases.
 ```{toctree}
 :maxdepth: 2
 
+2.3.4
 2.3.3
 2.3.2
 2.3.1

statemachine/callbacks.py

@@ -3,6 +3,7 @@
 from collections import defaultdict
 from collections import deque
 from enum import IntEnum
+from enum import IntFlag
 from enum import auto
 from inspect import isawaitable
 from inspect import iscoroutinefunction
@@ -26,10 +27,14 @@ class CallbackPriority(IntEnum):
     AFTER = 40
 
 
-class SpecReference(IntEnum):
-    NAME = 1
-    CALLABLE = 2
-    PROPERTY = 3
+class SpecReference(IntFlag):
+    NAME = auto()
+    CALLABLE = auto()
+    PROPERTY = auto()
+
+
+SPECS_ALL = SpecReference.NAME | SpecReference.CALLABLE | SpecReference.PROPERTY
+SPECS_SAFE = SpecReference.NAME
 
 
 class CallbackGroup(IntEnum):

statemachine/dispatcher.py

@@ -8,8 +8,8 @@
 from typing import Set
 from typing import Tuple
 
-from statemachine.callbacks import SpecReference
-
+from .callbacks import SPECS_ALL
+from .callbacks import SpecReference
 from .signature import SignatureAdapter
 
 if TYPE_CHECKING:
@@ -54,10 +54,18 @@ def from_listeners(cls, listeners: Iterable["Listener"]) -> "Listeners":
         all_attrs = set().union(*(listener.all_attrs for listener in listeners))
         return cls(listeners, all_attrs)
 
-    def resolve(self, specs: "CallbackSpecList", registry):
+    def resolve(
+        self,
+        specs: "CallbackSpecList",
+        registry,
+        allowed_references: SpecReference = SPECS_ALL,
+    ):
         found_convention_specs = specs.conventional_specs & self.all_attrs
         filtered_specs = [
-            spec for spec in specs if not spec.is_convention or spec.func in found_convention_specs
+            spec
+            for spec in specs
+            if spec.reference in allowed_references
+            and (not spec.is_convention or spec.func in found_convention_specs)
         ]
         if not filtered_specs:
             return
@@ -101,7 +109,7 @@ def _search_callable(self, spec) -> "Callable":
                 if func is not None and func.__func__ is spec.func:
                     return callable_method(spec.attr_name, func, config.resolver_id)
 
-        return callable_method(spec.func, spec.func, None)
+        return callable_method(spec.attr_name, spec.func, None)
 
     def _search_name(self, name) -> Generator["Callable", None, None]:
         for config in self.items:

statemachine/statemachine.py

@@ -9,11 +9,11 @@
 from typing import Dict
 from typing import List
 
-from statemachine.graph import iterate_states_and_transitions
-from statemachine.utils import run_async_from_sync
-
+from .callbacks import SPECS_ALL
+from .callbacks import SPECS_SAFE
 from .callbacks import CallbacksExecutor
 from .callbacks import CallbacksRegistry
+from .callbacks import SpecReference
 from .dispatcher import Listener
 from .dispatcher import Listeners
 from .engines.async_ import AsyncEngine
@@ -24,8 +24,10 @@
 from .exceptions import InvalidStateValue
 from .exceptions import TransitionNotAllowed
 from .factory import StateMachineMetaclass
+from .graph import iterate_states_and_transitions
 from .i18n import _
 from .model import Model
+from .utils import run_async_from_sync
 
 if TYPE_CHECKING:
     from .state import State
@@ -177,8 +179,12 @@ def bind_events_to(self, *targets):
                     continue
                 setattr(target, event.name, trigger)
 
-    def _add_listener(self, listeners: "Listeners"):
-        register = partial(listeners.resolve, registry=self._callbacks_registry)
+    def _add_listener(self, listeners: "Listeners", allowed_references: SpecReference = SPECS_ALL):
+        register = partial(
+            listeners.resolve,
+            registry=self._callbacks_registry,
+            allowed_references=allowed_references,
+        )
         for visited in iterate_states_and_transitions(self.states):
             register(visited._specs)
 
@@ -228,7 +234,8 @@ def add_listener(self, *listeners):
         """
         self._listeners.update({o: None for o in listeners})
         return self._add_listener(
-            Listeners.from_listeners(Listener.from_obj(o) for o in listeners)
+            Listeners.from_listeners(Listener.from_obj(o) for o in listeners),
+            allowed_references=SPECS_SAFE,
         )
 
     def _repr_html_(self):

tests/test_listener.py

@@ -1,5 +1,8 @@
 import pytest
 
+from statemachine.state import State
+from statemachine.statemachine import StateMachine
+
 EXPECTED_LOG_ADD = """Frodo on: draft--(add_job)-->draft
 Frodo enter: draft from add_job
 Frodo on: draft--(produce)-->producing
@@ -78,3 +81,27 @@ def on_enter_state(self, target, event):
 
         captured = capsys.readouterr()
         assert captured.out == EXPECTED_LOG_ADD
+
+
+def test_regression_456():
+    class TestListener:
+        def __init__(self):
+            pass
+
+    class MyMachine(StateMachine):
+        first = State("FIRST", initial=True)
+
+        second = State("SECOND")
+
+        first_selected = second.to(first)
+
+        second_selected = first.to(second)
+
+        @first.exit
+        def exit_first(self) -> None:
+            print("exit SLEEPING")
+
+    m = MyMachine()
+    m.add_listener(TestListener())
+
+    m.send("second_selected")