Merge pull request #1353 from ioam/clear_by_precedence

Stream clear method now supports policies by precedence

holoviews/plotting/bokeh/plot.py

@@ -296,7 +296,7 @@ def __init__(self, layout, ranges=None, layout_num=1, keys=None, **params):
         if self.top_level:
             self.comm = self.init_comm()
             self.traverse(lambda x: setattr(x, 'comm', self.comm))
-            self.traverse(lambda x: attach_streams(self, x.hmap, 1),
+            self.traverse(lambda x: attach_streams(self, x.hmap, 2),
                           [GenericElementPlot])
 
 
@@ -490,7 +490,7 @@ def __init__(self, layout, keys=None, **params):
         if self.top_level:
             self.comm = self.init_comm()
             self.traverse(lambda x: setattr(x, 'comm', self.comm))
-            self.traverse(lambda x: attach_streams(self, x.hmap, 1),
+            self.traverse(lambda x: attach_streams(self, x.hmap, 2),
                           [GenericElementPlot])
 
     def _init_layout(self, layout):

holoviews/plotting/mpl/plot.py

@@ -334,7 +334,7 @@ def __init__(self, layout, axis=None, create_axes=True, ranges=None,
         if self.top_level:
             self.comm = self.init_comm()
             self.traverse(lambda x: setattr(x, 'comm', self.comm))
-            self.traverse(lambda x: attach_streams(self, x.hmap, 1),
+            self.traverse(lambda x: attach_streams(self, x.hmap, 2),
                           [GenericElementPlot])
 
     def _get_size(self):
@@ -755,7 +755,7 @@ def __init__(self, layout, keys=None, **params):
         if self.top_level:
             self.comm = self.init_comm()
             self.traverse(lambda x: setattr(x, 'comm', self.comm))
-            self.traverse(lambda x: attach_streams(self, x.hmap, 1),
+            self.traverse(lambda x: attach_streams(self, x.hmap, 2),
                           [GenericElementPlot])
 
 

holoviews/plotting/plot.py

@@ -792,7 +792,7 @@ def __init__(self, overlay, ranges=None, batched=True, keys=None, **params):
         if self.top_level:
             self.comm = self.init_comm()
             self.traverse(lambda x: setattr(x, 'comm', self.comm))
-            self.traverse(lambda x: attach_streams(self, x.hmap, 1),
+            self.traverse(lambda x: attach_streams(self, x.hmap, 2),
                           [GenericElementPlot])
 
 

holoviews/plotting/util.py

@@ -408,7 +408,7 @@ def dim_axis_label(dimensions, separator=', '):
     return separator.join([d.pprint_label for d in dimensions])
 
 
-def attach_streams(plot, obj, precedence=0):
+def attach_streams(plot, obj, precedence=1.1):
     """
     Attaches plot refresh to all streams on the object.
     """

holoviews/streams.py

@@ -150,11 +150,26 @@ def subscribers(self):
         return [s for p, s in sorted(self._subscribers)]
 
 
-    def clear(self):
+    def clear(self, policy='all'):
         """
         Clear all subscribers registered to this stream.
+
+        The default policy of 'all' clears all subscribers. If policy is
+        set to 'user', only subscribers defined by the user are cleared
+        (precedence between zero and one). A policy of 'internal' clears
+        subscribers with precedence greater than unity used internally
+        by HoloViews.
         """
-        self._subscribers = []
+        policies = ['all', 'user', 'internal']
+        if policy not in policies:
+            raise ValueError('Policy for clearing subscribers must be one of %s' % policies)
+        if policy == 'all':
+            remaining = []
+        elif policy == 'user':
+            remaining = [(p,s) for (p,s) in self._subscribers if p > 1]
+        else:
+            remaining = [(p,s) for (p,s) in self._subscribers if p <= 1]
+        self._subscribers = remaining
 
 
     def reset(self):
@@ -172,6 +187,12 @@ def add_subscriber(self, subscriber, precedence=0):
         Register a callable subscriber to this stream which will be
         invoked either when event is called or when this stream is
         passed to the trigger classmethod.
+
+        Precedence allows the subscriber ordering to be
+        controlled. Users should only add subscribers with precedence
+        between zero and one while HoloViews itself reserves the use of
+        higher precedence values. Subscribers with high precedence are
+        invoked later than ones with low precedence.
         """
         if not callable(subscriber):
             raise TypeError('Subscriber must be a callable.')

tests/testdynamic.py

@@ -444,6 +444,45 @@ def history_callback(x, history=deque(maxlen=10)):
         self.assertEqual(dmap[()], Curve([1, 1, 1, 2, 2, 2]))
 
 
+class StreamSubscribersAddandClear(ComparisonTestCase):
+
+    def setUp(self):
+        self.fn1 = lambda x: x
+        self.fn2 = lambda x: x**2
+        self.fn3 = lambda x: x**3
+        self.fn4 = lambda x: x**4
+
+    def test_subscriber_clear_all(self):
+        pointerx = PointerX(x=2)
+        pointerx.add_subscriber(self.fn1, precedence=0)
+        pointerx.add_subscriber(self.fn2, precedence=1)
+        pointerx.add_subscriber(self.fn3, precedence=1.5)
+        pointerx.add_subscriber(self.fn4, precedence=10)
+        self.assertEqual(pointerx.subscribers,  [self.fn1,self.fn2,self.fn3,self.fn4])
+        pointerx.clear('all')
+        self.assertEqual(pointerx.subscribers,  [])
+
+    def test_subscriber_clear_user(self):
+        pointerx = PointerX(x=2)
+        pointerx.add_subscriber(self.fn1, precedence=0)
+        pointerx.add_subscriber(self.fn2, precedence=1)
+        pointerx.add_subscriber(self.fn3, precedence=1.5)
+        pointerx.add_subscriber(self.fn4, precedence=10)
+        self.assertEqual(pointerx.subscribers,  [self.fn1,self.fn2,self.fn3,self.fn4])
+        pointerx.clear('user')
+        self.assertEqual(pointerx.subscribers,  [self.fn3,self.fn4])
+
+
+    def test_subscriber_clear_internal(self):
+        pointerx = PointerX(x=2)
+        pointerx.add_subscriber(self.fn1, precedence=0)
+        pointerx.add_subscriber(self.fn2, precedence=1)
+        pointerx.add_subscriber(self.fn3, precedence=1.5)
+        pointerx.add_subscriber(self.fn4, precedence=10)
+        self.assertEqual(pointerx.subscribers,  [self.fn1,self.fn2,self.fn3,self.fn4])
+        pointerx.clear('internal')
+        self.assertEqual(pointerx.subscribers,  [self.fn1,self.fn2])
+
 
 class DynamicStreamReset(ComparisonTestCase):