Added lazy-loading support to ListenerManager. (#307)

* Added lazy-loading support to ListenerManager.
Made OnEntityOutput lazy-loaded to fix loading conflict with SourceMod (see #306).

* Update __init__.py

Fixed a typo (thank @CookStar).
Added missing entry to __all__ declaration.

* Replaced the static dispatchers with virtual overrides (thanks @Ayuto).
Removed redundant attribute retrievals.

Author: jordanbriere

addons/source-python/packages/source-python/__init__.py

@@ -158,26 +158,25 @@ def setup_data():
         'BaseEntityOutput',
         GameConfigObj(SP_DATA_PATH / 'entity_output' / 'CBaseEntityOutput.ini'))
 
+    from _entities import BaseEntityOutput
     try:
         _fire_output = entities._BaseEntityOutput.fire_output
 
-        from _entities import BaseEntityOutput
         BaseEntityOutput.fire_output = _fire_output
     except ValueError:
         from warnings import warn
         warn(
             'Did not find address for BaseEntityOutput.fire_output. '
             'OnEntityOutput listener will not fire.'
         )
+        BaseEntityOutput.fire_output = NotImplemented
     except AttributeError:
         from warnings import warn
         warn(
             'BaseEntityOutput.fire_output not found. '
             'OnEntityOutput listener will not fire.'
         )
-    else:
-        import listeners
-        _fire_output.add_pre_hook(listeners._pre_fire_output)
+        BaseEntityOutput.fire_output = NotImplemented
 
 
 # =============================================================================

addons/source-python/packages/source-python/listeners/__init__.py

@@ -24,6 +24,8 @@
 from cvars import cvar
 #   Engines
 from engines.server import server_game_dll
+#   Entities
+from entities import BaseEntityOutput
 from entities.datamaps import Variant
 from entities.helpers import find_output_name
 #   Memory
@@ -91,6 +93,7 @@
            'OnEntityCreated',
            'OnEntityDeleted',
            'OnEntityOutput',
+           'OnEntityOutputListenerManager',
            'OnEntityPreSpawned',
            'OnEntitySpawned',
            'OnLevelInit',
@@ -157,7 +160,6 @@
 on_plugin_loading_manager = ListenerManager()
 on_plugin_unloading_manager = ListenerManager()
 on_level_end_listener_manager = ListenerManager()
-on_entity_output_listener_manager = ListenerManager()
 
 _check_for_update = ConVar(
     'sp_check_for_update',
@@ -281,6 +283,36 @@ class OnClientSettingsChanged(ListenerManagerDecorator):
     manager = on_client_settings_changed_listener_manager
 
 
+class OnEntityOutputListenerManager(ListenerManager):
+    """Register/unregister an EntityOutput listener."""
+
+    def initialize(self):
+        """Called when the first callback is being registered."""
+        # Get the fire_output method
+        fire_output = BaseEntityOutput.fire_output
+
+        # If the fire_output method is not implemented, exit the call
+        if fire_output is NotImplemented:
+            return
+
+        # Register the hook on fire_output
+        fire_output.add_pre_hook(_pre_fire_output)
+
+    def finalize(self):
+        """Called when the last callback is being unregistered."""
+        # Get the fire_output method
+        fire_output = BaseEntityOutput.fire_output
+
+        # If the fire_output method is not implemented, exit the call
+        if fire_output is NotImplemented:
+            return
+
+        # Unregister the hook on fire_output
+        fire_output.remove_pre_hook(_pre_fire_output)
+
+on_entity_output_listener_manager = OnEntityOutputListenerManager()
+
+
 class OnEntityOutput(ListenerManagerDecorator):
     """Register/unregister an EntityOutput listener."""
 

src/core/modules/listeners/listeners_manager.cpp

@@ -41,6 +41,9 @@ void CListenerManager::RegisterListener(PyObject* pCallable)
 	// Is the callable already in the vector?
 	if( !IsRegistered(oCallable) )
 	{
+		if (!GetCount())
+			Initialize();
+
 		m_vecCallables.AddToTail(oCallable);
 	}
 	else {
@@ -64,6 +67,9 @@ void CListenerManager::UnregisterListener(PyObject* pCallable)
 	}
 	else {
 		m_vecCallables.Remove(index);
+
+		if (!GetCount())
+			Finalize();
 	}
 }
 
@@ -92,6 +98,28 @@ int CListenerManager::GetCount()
 }
 
 
+//-----------------------------------------------------------------------------
+// Called when the first callback is being registered.
+//-----------------------------------------------------------------------------
+void CListenerManager::Initialize()
+{
+	override initialize = get_override("initialize");
+	if (!initialize.is_none())
+		initialize();
+}
+
+
+//-----------------------------------------------------------------------------
+// Called when the last callback is being unregistered.
+//-----------------------------------------------------------------------------
+void CListenerManager::Finalize()
+{
+	override finalize = get_override("finalize");
+	if (!finalize.is_none())
+		finalize();
+}
+
+
 //-----------------------------------------------------------------------------
 // Return whether or not the given callback is registered.
 //-----------------------------------------------------------------------------

src/core/modules/listeners/listeners_manager.h

@@ -79,7 +79,7 @@
 //-----------------------------------------------------------------------------
 // CListenerManager class.
 //-----------------------------------------------------------------------------
-class CListenerManager
+class CListenerManager: public wrapper<CListenerManager>
 {
 public:
 	void RegisterListener(PyObject* pCallable);
@@ -90,6 +90,9 @@ class CListenerManager
 	object __getitem__(unsigned int index);
 	void clear();
 
+	virtual void Initialize();
+	virtual void Finalize();
+
 	int FindCallback(object oCallback);
 
 public:

src/core/modules/listeners/listeners_wrap.cpp

@@ -119,6 +119,16 @@ void export_listener_managers(scope _listeners)
 			&CListenerManager::clear,
 			"Remove all registered callbacks."
 		)
+
+		.def("initialize",
+			&CListenerManager::Initialize,
+			"Called when the first callback is being registered."
+		)
+
+		.def("finalize",
+			&CListenerManager::Finalize,
+			"Called when the last callback is being unregistered."
+		)
 	;
 
 	_listeners.attr("on_client_active_listener_manager") = object(ptr(GetOnClientActiveListenerManager()));