Adding directional link widget

IPython/html/static/widgets/js/widget_link.js

@@ -1,48 +1,87 b''
 // 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;
         },
     });
+
+    var DirectionalLinkModel = widget.WidgetModel.extend({
+        initialize: function() {
+            this.on("change", this.update_bindings, this);
+            this.on("destroy", function() {
+                if (this.source) {
+                    this.source[0].off("change:" + this.source[1], null, this);
+                }
+            }, this);
+        },
+        update_bindings: function() {
+            if (this.source) {
+                this.source[0].off("change:" + this.source[1], null, this);
+            }
+            this.source = this.get("source");
+			if (this.source) {
+                this.source[0].on("change:" + this.source[1], function() { this.update_value(this.source); }, this);
+                this.update_value(this.source);
+            }
+        },
+        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(this.get("targets"),
+                   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,
+        "DirectionalLinkModel": DirectionalLinkModel,
     }
 });

IPython/html/widgets/__init__.py

@@ -1,24 +1,24 b''
 from .widget import Widget, DOMWidget, CallbackDispatcher
 
 from .widget_bool import Checkbox, ToggleButton
 from .widget_button import Button
 from .widget_box import Box, Popup, FlexBox, HBox, VBox
 from .widget_float import FloatText, BoundedFloatText, FloatSlider, FloatProgress, FloatRangeSlider
 from .widget_image import Image
 from .widget_int import IntText, BoundedIntText, IntSlider, IntProgress, IntRangeSlider
 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
+from .widget_link import Link, link, DirectionalLink, dlink
 
 # Deprecated classes
 from .widget_bool import CheckboxWidget, ToggleButtonWidget
 from .widget_button import ButtonWidget
 from .widget_box import ContainerWidget, PopupWidget
 from .widget_float import FloatTextWidget, BoundedFloatTextWidget, FloatSliderWidget, FloatProgressWidget
 from .widget_image import ImageWidget
 from .widget_int import IntTextWidget, BoundedIntTextWidget, IntSliderWidget, IntProgressWidget
 from .widget_selection import RadioButtonsWidget, ToggleButtonsWidget, DropdownWidget, SelectWidget
 from .widget_selectioncontainer import TabWidget, AccordionWidget
 from .widget_string import HTMLWidget, LatexWidget, TextWidget, TextareaWidget

IPython/html/widgets/widget_link.py

@@ -1,35 +1,54 b''
 """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
+from IPython.utils.traitlets import Unicode, Tuple, Any
 
 #-----------------------------------------------------------------------------
 # 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)
+
+
+class DirectionalLink(Widget):
+    """Directional Link Widget"""
+    _model_name = Unicode('DirectionalLinkModel', sync=True)
+    targets = Any(sync=True)
+    source = Tuple(sync=True)
+
+    # Does not quite behave like other widgets but reproduces
+    # the behavior of IPython.utils.traitlets.directional_link
+    def __init__(self, source, targets=(), **kwargs):
+        kwargs['source'] = source
+        kwargs['targets'] = targets
+        super(DirectionalLink, self).__init__(**kwargs)
+
+
+def dlink(source, *targets):
+    return DirectionalLink(source, targets)