Fixes for dynamic overlaying

holoviews/core/overlay.py

@@ -23,7 +23,7 @@ class Overlayable(object):
     """
 
     def __mul__(self, other):
-        if hasattr(other, 'call_mode'):
+        if type(other).__name__ == 'DynamicMap':
             from .operation import DynamicOperation
             def dynamic_mul(element):
                 return self * element

holoviews/core/spaces.py

@@ -112,12 +112,14 @@ def dynamic_mul(*key):
             layers = []
             try:
                 _, self_el = util.get_dynamic_item(self, dimensions, key)
-                layers.append(self_el)
+                if self_el is not None:
+                    layers.append(self_el)
             except KeyError:
                 pass
             try:
                 _, other_el = util.get_dynamic_item(other, dimensions, key)
-                layers.append(other_el)
+                if other_el is not None:
+                    layers.append(other_el)
             except KeyError:
                 pass
             return Overlay(layers)
@@ -145,6 +147,10 @@ def __mul__(self, other):
             self_in_other = self_set.issubset(other_set)
             other_in_self = other_set.issubset(self_set)
             dimensions = self.kdims
+
+            if isinstance(self, DynamicMap) or isinstance(other, DynamicMap):
+                return self._dynamic_mul(dimensions, other)
+
             if self_in_other and other_in_self: # superset of each other
                 super_keys = sorted(set(self._dimension_keys() + other._dimension_keys()))
             elif self_in_other: # self is superset
@@ -155,9 +161,6 @@ def __mul__(self, other):
             else: # neither is superset
                 raise Exception('One set of keys needs to be a strict subset of the other.')
 
-            if isinstance(self, DynamicMap) or (other, DynamicMap):
-                return self._dynamic_mul(dimensions, other)
-
             items = []
             for dim_keys in super_keys:
                 # Generate keys for both subset and superset and sort them by the dimension index.

holoviews/core/util.py

@@ -897,7 +897,8 @@ def get_dynamic_item(map_obj, dimensions, key):
         dims = {d.name: k for d, k in zip(dimensions, key)
                 if d in map_obj.kdims}
         key = tuple(dims.get(d.name) for d in map_obj.kdims)
-        el = map_obj.select([lambda x: hasattr(x, 'call_mode')], **dims)
+        el = map_obj.select([lambda x: type(other).__name__ == 'DynamicMap'],
+                            **dims)
     elif key < map_obj.counter:
         key_offset = max([key-map_obj.cache_size, 0])
         key = map_obj.keys()[min([key-key_offset,