Parent is now mandatory when creating a new BaseInstance class

src/myfasthtml/core/instances.py

@@ -1,4 +1,5 @@
 import uuid
+from typing import Self
 
 from myfasthtml.controls.helpers import Ids
 
@@ -17,10 +18,11 @@ class BaseInstance:
   Base class for all instances (manageable by InstancesManager)
   """
   
-  def __init__(self, session: dict, prefix: str, _id: str, auto_register: bool = True):
+  def __init__(self, session: dict, prefix: str, _id: str, parent: Self, auto_register: bool = True):
     self._session = session
     self._id = _id
     self._prefix = prefix
+    self._parent = parent
     if auto_register:
       InstancesManager.register(session, self)
   
@@ -39,8 +41,8 @@ class SingleInstance(BaseInstance):
   Base class for instances that can only have one instance at a time.
   """
   
-  def __init__(self, session: dict, prefix: str, auto_register: bool = True):
-    super().__init__(session, prefix, prefix, auto_register)
+  def __init__(self, session: dict, prefix: str, parent, auto_register: bool = True):
+    super().__init__(session, prefix, prefix, parent, auto_register)
 
 
 class UniqueInstance(BaseInstance):
@@ -49,8 +51,8 @@ class UniqueInstance(BaseInstance):
   Does not throw exception if the instance already exists, it simply overwrites it.
   """
   
-  def __init__(self, session: dict, prefix: str, auto_register: bool = True):
-    super().__init__(session, prefix, prefix, auto_register)
+  def __init__(self, prefix: str, parent: BaseInstance, auto_register: bool = True):
+    super().__init__(parent.get_session(), prefix, prefix, parent, auto_register)
     self._prefix = prefix
 
 
@@ -59,8 +61,8 @@ class MultipleInstance(BaseInstance):
   Base class for instances that can have multiple instances at a time.
   """
   
-  def __init__(self, session: dict, prefix: str, auto_register: bool = True, _id=None):
-    super().__init__(session, prefix, _id or f"{prefix}-{str(uuid.uuid4())}", auto_register)
+  def __init__(self, prefix: str, parent: BaseInstance, auto_register: bool = True, _id=None):
+    super().__init__(parent.get_session(), prefix, _id or f"{prefix}-{str(uuid.uuid4())}", parent, auto_register)
     self._prefix = prefix
 
 
@@ -84,12 +86,13 @@ class InstancesManager:
     return instance
   
   @staticmethod
-  def get(session: dict, instance_id: str, instance_type: type = None, *args, **kwargs):
+  def get(session: dict, instance_id: str, instance_type: type = None, parent: BaseInstance = None, *args, **kwargs):
     """
     Get or create an instance of the given type (from its id)
     :param session:
     :param instance_id:
     :param instance_type:
+    :param parent:
     :param args:
     :param kwargs:
     :return:
@@ -100,7 +103,9 @@ class InstancesManager:
       return InstancesManager.instances[key]
     except KeyError:
       if instance_type:
-        return instance_type(session, *args, **kwargs)  # it will be automatically registered
+        if not issubclass(instance_type, SingleInstance):
+          assert parent is not None, "Parent instance must be provided if not SingleInstance"
+        return instance_type(session, parent=parent, *args, **kwargs)  # it will be automatically registered
       else:
         raise
   
@@ -119,3 +124,6 @@ class InstancesManager:
   @staticmethod
   def reset():
     return InstancesManager.instances.clear()
+
+
+RootInstance = SingleInstance(special_session, Ids.Root, None)