Remove stray _IMPL_NAMEs and put _create after priming attributes

core/src/toga/widgets/base.py

@@ -16,8 +16,6 @@
 
 
 class Widget(Node):
-    _IMPL_NAME = "Widget"
-
     _MIN_WIDTH = 100
     _MIN_HEIGHT = 100
 
@@ -39,13 +37,13 @@ def __init__(
             applicator=None,
         )
 
-        # Create and assign _impl
-        self._create()
-
         self._id = str(id if id else identifier(self))
         self._window: Window | None = None
         self._app: App | None = None
 
+        # Create and assign _impl
+        self._create()
+
         self.applicator = TogaApplicator()
 
         ##############################################

core/src/toga/widgets/dateinput.py

@@ -28,8 +28,6 @@ def __call__(self, widget: DateInput, /, **kwargs: Any) -> object:
 
 
 class DateInput(Widget):
-    _IMPL_NAME = "DateInput"
-
     _MIN_WIDTH = 200
 
     def __init__(

core/src/toga/widgets/mapview.py

@@ -11,8 +11,6 @@
 
 
 class MapPin:
-    _IMPL_NAME = "MapPin"
-
     def __init__(
         self,
         location: toga.LatLng | tuple[float, float],