From d6c978584acd1a7c879ce0e7a368f4db7e5aace5 2014-09-26 18:32:59
From: Jason Grout <jgrout6@bloomberg.net>
Date: 2014-09-26 18:32:59
Subject: [PATCH] Adding Link widget

---

diff --git a/IPython/html/static/widgets/js/widget_link.js b/IPython/html/static/widgets/js/widget_link.js
new file mode 100644
index 0000000..6c28427
--- /dev/null
+++ b/IPython/html/static/widgets/js/widget_link.js
@@ -0,0 +1,48 @@
+// Copyright (c) IPython Development Team.
+// Distributed under the terms of the Modified BSD License.
+
+define([
+    "widgets/js/widget",
+    "jquery",
+], function(widget, $){
+    var LinkModel = widget.WidgetModel.extend({
+        initialize: function() {
+            this.on("change:widgets", function(model, value, options) {
+                this.update_bindings(model.previous("widgets") || [], value);
+				this.update_value(this.get("widgets")[0]);
+            }, this);
+	        this.on("destroy", function(model, collection, options) {
+                this.update_bindings(this.get("widgets"), []);
+            }, this);
+        },
+        update_bindings: function(oldlist, newlist) {
+            var that = this;
+            _.each(oldlist, function(elt) {elt[0].off("change:" + elt[1], null, that);});
+            _.each(newlist, function(elt) {elt[0].on("change:" + elt[1],
+						     function(model, value, options) {
+							     that.update_value(elt);
+						     }, that);
+					   // TODO: register for any destruction handlers
+					   // to take an item out of the list
+					  });
+        },
+        update_value: function(elt) {
+            if (this.updating) {return;}
+            var model = elt[0];
+            var attr = elt[1];
+            var new_value = model.get(attr);
+            this.updating = true;
+            _.each(_.without(this.get("widgets"), elt),
+                   function(element, index, list) {
+						if (element[0]) {
+							element[0].set(element[1], new_value);
+							element[0].save_changes();
+						}
+                   }, this);
+            this.updating = false;
+        },
+    });
+    return {
+        "LinkModel": LinkModel,
+    }
+});
diff --git a/IPython/html/widgets/__init__.py b/IPython/html/widgets/__init__.py
index 2e93522..552f32e 100644
--- a/IPython/html/widgets/__init__.py
+++ b/IPython/html/widgets/__init__.py
@@ -10,6 +10,7 @@ from .widget_selection import RadioButtons, ToggleButtons, Dropdown, Select
 from .widget_selectioncontainer import Tab, Accordion
 from .widget_string import HTML, Latex, Text, Textarea
 from .interaction import interact, interactive, fixed, interact_manual
+from .widget_link import Link, link
 
 # Deprecated classes
 from .widget_bool import CheckboxWidget, ToggleButtonWidget
diff --git a/IPython/html/widgets/widget_link.py b/IPython/html/widgets/widget_link.py
new file mode 100644
index 0000000..1753973
--- /dev/null
+++ b/IPython/html/widgets/widget_link.py
@@ -0,0 +1,35 @@
+"""Link and DirectionalLink classes.
+
+Represents a button in the frontend using a widget.  Allows user to listen for
+click events on the button and trigger backend code when the clicks are fired.
+"""
+#-----------------------------------------------------------------------------
+# Copyright (c) 2013, the IPython Development Team.
+#
+# Distributed under the terms of the Modified BSD License.
+#
+# The full license is in the file COPYING.txt, distributed with this software.
+#-----------------------------------------------------------------------------
+
+#-----------------------------------------------------------------------------
+# Imports
+#-----------------------------------------------------------------------------
+from .widget import Widget
+from IPython.utils.traitlets import Unicode, Tuple
+
+#-----------------------------------------------------------------------------
+# Classes
+#-----------------------------------------------------------------------------
+
+
+class Link(Widget):
+    """Link Widget"""
+    _model_name = Unicode('LinkModel', sync=True)
+    widgets = Tuple(sync=True, allow_none=False)
+
+    def __init__(self, widgets=(), **kwargs):
+        kwargs['widgets'] = widgets
+        super(Link, self).__init__(**kwargs)
+
+def link(*args):
+    return Link(widgets=args)