split pythonization callback to predicate and modifcation

python/podio/pythonizations/collection_subscript.py

@@ -12,12 +12,15 @@ def priority(cls):
         return 50
 
     @classmethod
-    def callback(cls, class_, name):
+    def filter(cls, class_, name):
+        return issubclass(class_, cppyy.gbl.podio.CollectionBase)
+
+    @classmethod
+    def modify(cls, class_, name):
         def get_item(self, i):
             try:
                 return self.at(i)
             except cppyy.gbl.std.out_of_range:
                 raise IndexError("collection index out of range") from None
 
-        if issubclass(class_, cppyy.gbl.podio.CollectionBase):
-            class_.__getitem__ = get_item
+        class_.__getitem__ = get_item

python/podio/pythonizations/utils/pythonizer.py

@@ -12,14 +12,46 @@ class Pythonizer(metaclass=ABCMeta):
     @classmethod
     @abstractmethod
     def priority(cls):
-        """Order in which the pythonizations are applied"""
+        """Order in which the pythonizations are applied
+
+        Returns:
+            int: Priority
+        """
+
+    @classmethod
+    @abstractmethod
+    def filter(cls, class_, name):
+        """
+        Abstract classmethod to filter classes to which the pythonizations should be applied
+
+        Args:
+            class_ (type): Class object.
+            name (str): Name of the class.
+
+        Returns:
+            bool: True if class should be pythonized.
+        """
 
     @classmethod
     @abstractmethod
-    def callback(cls, class_, name):
-        """Pythonization callback"""
+    def modify(cls, class_, name):
+        """Abstract classmethod modifying classes to be pythonized
+
+        Args:
+            class_ (type): Class object.
+            name (str): Name of the class.
+        """
 
     @classmethod
     def register(cls, namespace):
-        """Helper method to apply the pythonization to the given namespace"""
-        cppyy.py.add_pythonization(cls.callback, namespace)
+        """Helper method to apply the pythonization to the given namespace
+
+        Args:
+            namespace (str): Namespace to by pythonized
+        """
+
+        def pythonization_callback(class_, name):
+            if cls.filter(class_, name):
+                cls.modify(class_, name)
+
+        cppyy.py.add_pythonization(pythonization_callback, namespace)