View parameters store callback per Parameterized instance

paramnb/__init__.py

@@ -198,7 +198,7 @@ def action_cb(button):
 
         kw['continuous_update']=self.p.continuous_update
 
-        if hasattr(p_obj, 'callback'):
+        if hasattr(p_obj, 'callbacks'):
             kw.pop('value', None)
 
         if hasattr(p_obj, 'get_range'):
@@ -209,7 +209,7 @@ def action_cb(button):
 
         w = widget_class(**kw)
 
-        if hasattr(p_obj, 'callback') and value is not None:
+        if hasattr(p_obj, 'callbacks') and value is not None:
             self._update_trait(p_name, p_obj.renderer(value), w)
 
         def change_event(event):
@@ -237,8 +237,8 @@ def change_event(event):
             else:
                 self._changed[p_name] = new_values
 
-        if hasattr(p_obj, 'callback'):
-            p_obj.callback = functools.partial(self._update_trait, p_name)
+        if hasattr(p_obj, 'callbacks'):
+            p_obj.callbacks[id(self.parameterized)] = functools.partial(self._update_trait, p_name)
         else:
             w.observe(change_event, 'value')
 

paramnb/view.py

@@ -10,17 +10,18 @@ class _View(param.Parameter):
     and may optionally supply the desired size of the viewport.
     """
 
-    __slots__ = ['callback', 'renderer']
+    __slots__ = ['callbacks', 'renderer']
 
     def __init__(self, default=None, callback=None, renderer=None, **kwargs):
-        self.callback = None
+        self.callbacks = {}
         self.renderer = (lambda x: x) if renderer is None else renderer
         super(_View, self).__init__(default, **kwargs)
 
     def __set__(self, obj, val):
         super(_View, self).__set__(obj, val)
-        if self.callback:
-            self.callback(self.renderer(val))
+        obj_id = id(obj)
+        if obj_id in self.callbacks:
+            self.callbacks[obj_id](self.renderer(val))
 
 
 class HTML(_View):