Ensure Link is idempotent (#3254)

holoviz · Dec 4, 2018 · f4575aa · f4575aa
1 parent dea2f0b
commit f4575aa
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Showing 3 changed files with 22 additions and 1 deletion.
diff --git a/holoviews/plotting/bokeh/callbacks.py b/holoviews/plotting/bokeh/callbacks.py
@@ -1260,6 +1260,9 @@ class DataLinkCallback(LinkCallback):
     def __init__(self, root_model, link, source_plot, target_plot):
         src_cds = source_plot.handles['source']
         tgt_cds = target_plot.handles['source']
+        if src_cds is tgt_cds:
+            return
+
         src_len = [len(v) for v in src_cds.data.values()]
         tgt_len = [len(v) for v in tgt_cds.data.values()]
         if src_len[0] != tgt_len[0]:

diff --git a/holoviews/plotting/links.py b/holoviews/plotting/links.py
@@ -64,6 +64,15 @@ def link(self):
         Registers the Link
         """
         if self.source in self.registry:
+            links = self.registry[self.source]
+            params = {
+                k: v for k, v in self.get_param_values() if k != 'name'}
+            for link in links:
+                link_params = {
+                    k: v for k, v in link.get_param_values() if k != 'name'}
+                if (type(link) is type(self) and link.source is self.source
+                    and link.target is self.target and params == link_params):
+                    return
             self.registry[self.source].append(self)
         else:
             self.registry[self.source] = [self]

diff --git a/holoviews/tests/plotting/bokeh/testlinks.py b/holoviews/tests/plotting/bokeh/testlinks.py
@@ -4,7 +4,7 @@
 
 from holoviews.core.spaces import DynamicMap
 from holoviews.element import Curve, Polygons, Table, Scatter, Path, Points
-from holoviews.plotting.links import (RangeToolLink, DataLink)
+from holoviews.plotting.links import (Link, RangeToolLink, DataLink)
 
 try:
     from holoviews.plotting.bokeh.util import bokeh_version
@@ -116,3 +116,12 @@ def test_data_link_list(self):
         plot = bokeh_renderer.get_plot(layout)
         path_plot, table_plot = (sp.subplots['main'] for sp in plot.subplots.values())
         self.assertIs(path_plot.handles['source'], table_plot.handles['source'])
+
+    def test_data_link_idempotent(self):
+        table1 = Table([], 'A', 'B')
+        table2 = Table([], 'C', 'D')
+        link1 = DataLink(table1, table2)
+        DataLink(table1, table2)
+        self.assertEqual(len(Link.registry[table1]), 1)
+        self.assertIn(link1, Link.registry[table1])
+