refactor: bind providers explicitly to a registry with attach/detach

Signed-off-by: Federico Bond <[email protected]>

Author: federicobond

openfeature/provider/__init__.py

@@ -23,6 +23,15 @@ class ProviderStatus(Enum):
 
 
 class FeatureProvider(typing.Protocol):  # pragma: no cover
+    def attach(
+        self,
+        on_emit: typing.Callable[
+            [FeatureProvider, ProviderEvent, ProviderEventDetails], None
+        ],
+    ) -> None: ...
+
+    def detach(self) -> None: ...
+
     def initialize(self, evaluation_context: EvaluationContext) -> None: ...
 
     def shutdown(self) -> None: ...
@@ -68,6 +77,18 @@ def resolve_object_details(
 
 
 class AbstractProvider(FeatureProvider):
+    def attach(
+        self,
+        on_emit: typing.Callable[
+            [FeatureProvider, ProviderEvent, ProviderEventDetails], None
+        ],
+    ) -> None:
+        self._on_emit = on_emit
+
+    def detach(self) -> None:
+        if hasattr(self, "_on_emit"):
+            del self._on_emit
+
     def initialize(self, evaluation_context: EvaluationContext) -> None:
         pass
 
@@ -141,6 +162,5 @@ def emit_provider_stale(self, details: ProviderEventDetails) -> None:
         self.emit(ProviderEvent.PROVIDER_STALE, details)
 
     def emit(self, event: ProviderEvent, details: ProviderEventDetails) -> None:
-        from openfeature.provider._registry import provider_registry
-
-        provider_registry.dispatch_event(self, event, details)
+        if hasattr(self, "_on_emit"):
+            self._on_emit(self, event, details)

openfeature/provider/_registry.py

@@ -71,6 +71,7 @@ def _get_evaluation_context(self) -> EvaluationContext:
         return get_evaluation_context()
 
     def _initialize_provider(self, provider: FeatureProvider) -> None:
+        provider.attach(self.dispatch_event)
         try:
             if hasattr(provider, "initialize"):
                 provider.initialize(self._get_evaluation_context())
@@ -106,6 +107,7 @@ def _shutdown_provider(self, provider: FeatureProvider) -> None:
                     error_code=ErrorCode.PROVIDER_FATAL,
                 ),
             )
+        provider.detach()
 
     def get_provider_status(self, provider: FeatureProvider) -> ProviderStatus:
         return self._provider_status.get(provider, ProviderStatus.NOT_READY)