add callback for when the script is unloaded

modules/script_callbacks.py

@@ -71,6 +71,7 @@ callback_map = dict(
     callbacks_before_component=[],
     callbacks_after_component=[],
     callbacks_image_grid=[],
+    callbacks_script_unloaded=[],
 )
 
 
@@ -171,6 +172,14 @@ def image_grid_callback(params: ImageGridLoopParams):
             report_exception(c, 'image_grid')
 
 
+def script_unloaded_callback():
+    for c in reversed(callback_map['callbacks_script_unloaded']):
+        try:
+            c.callback()
+        except Exception:
+            report_exception(c, 'script_unloaded')
+
+
 def add_callback(callbacks, fun):
     stack = [x for x in inspect.stack() if x.filename != __file__]
     filename = stack[0].filename if len(stack) > 0 else 'unknown file'
@@ -202,7 +211,7 @@ def on_app_started(callback):
 
 def on_model_loaded(callback):
     """register a function to be called when the stable diffusion model is created; the model is
-    passed as an argument"""
+    passed as an argument; this function is also called when the script is reloaded. """
     add_callback(callback_map['callbacks_model_loaded'], callback)
 
 
@@ -279,3 +288,10 @@ def on_image_grid(callback):
        - params: ImageGridLoopParams - parameters to be used for grid creation. Can be modified.
     """
     add_callback(callback_map['callbacks_image_grid'], callback)
+
+
+def on_script_unloaded(callback):
+    """register a function to be called before the script is unloaded. Any hooks/hijacks/monkeying about that
+    the script did should be reverted here"""
+
+    add_callback(callback_map['callbacks_script_unloaded'], callback)