Allow switching kernel from the notebook UI

IPython/html/static/notebook/js/kernelselector.js

@@ -0,0 +1,58 @@
+// Copyright (c) IPython Development Team.
+// Distributed under the terms of the Modified BSD License.
+
+define([
+    'base/js/namespace',
+    'jquery',
+    'base/js/utils',
+], function(IPython, $, utils) {
+    "use strict";
+    
+    var KernelSelector = function(selector, notebook) {
+        this.selector = selector;
+        this.notebook = notebook;
+        this.kernelspecs = {};
+        this.current = "python";
+        if (this.selector !== undefined) {
+            this.element = $(selector);
+            this.style();
+            this.request_kernelspecs();
+        }
+    };
+    
+    KernelSelector.prototype.style = function() {
+    };
+    
+    KernelSelector.prototype.request_kernelspecs = function() {
+        var url = utils.url_join_encode(this.notebook.base_url, 'api/kernelspecs');
+        $.ajax(url, {success: $.proxy(this.got_kernelspecs, this)});
+    };
+    
+    KernelSelector.prototype.got_kernelspecs = function(data, status, xhr) {
+        this.kernelspecs = {};
+        var menu = this.element.find("#kernel_selector");
+        for (var i = 0; i < data.length; i++) {
+            var ks = data[i];
+            this.kernelspecs[ks.name] = ks;
+            var ksentry = $("<li>").attr("id", "kernel-" +ks.name).append($('<a>')
+                .attr('href', '#')
+                .click($.proxy(this.change_kernel, this, ks.name))
+                .text(ks.display_name));
+            menu.append(ksentry);
+        }
+    };
+
+    KernelSelector.prototype.change_kernel = function(kernel_name) {
+        console.log("change_kernel " + kernel_name + " from " + this.current);
+        if (kernel_name === this.current) {
+            return;
+        }
+        this.notebook.session.delete();
+        this.notebook.start_session(kernel_name);
+        this.current = kernel_name;
+        var display_name = this.kernelspecs[kernel_name].display_name;
+        this.element.find("#current_kernel_spec").text(display_name);
+    };
+    
+    return {'KernelSelector': KernelSelector};
+});

IPython/html/static/notebook/js/main.js

@@ -18,6 +18,7 @@ require([
     'notebook/js/savewidget',
     'notebook/js/keyboardmanager',
     'notebook/js/config',
+    'notebook/js/kernelselector',
     // only loaded, not used:
     'custom/custom',
 ], function(
@@ -36,7 +37,8 @@ require([
     notificationarea, 
     savewidget, 
     keyboardmanager,
-    config
+    config,
+    kernelselector
     ) {
     "use strict";
 
@@ -90,6 +92,8 @@ require([
         notebook: notebook,
         keyboard_manager: keyboard_manager});
     notification_area.init_notification_widgets();
+    var kernel_selector = new kernelselector.KernelSelector(
+        '#kernel_selector_widget', notebook);
 
     $('body').append('<div id="fonttest"><pre><span id="test1">x</span>'+
                      '<span id="test2" style="font-weight: bold;">x</span>'+

IPython/html/static/notebook/js/notebook.js

@@ -1496,7 +1496,11 @@ define([
      * 
      * @method start_session
      */
-    Notebook.prototype.start_session = function () {
+    Notebook.prototype.start_session = function (kernel_name) {
+        if (kernel_name === undefined) {
+            kernel_name = this.default_kernel_name;
+        }
+        console.log("start_session", kernel_name);
         this.session = new session.Session({
             base_url: this.base_url,
             ws_url: this.ws_url,
@@ -1505,7 +1509,7 @@ define([
             // For now, create all sessions with the 'python' kernel, which is the
             // default. Later, the user will be able to select kernels. This is
             // overridden if KernelManager.kernel_cmd is specified for the server.
-            kernel_name: this.default_kernel_name,
+            kernel_name: kernel_name,
             notebook: this});
 
         this.session.start($.proxy(this._session_started, this));

IPython/html/templates/notebook.html

@@ -40,6 +40,12 @@ class="notebook_app"
     <span id="autosave_status"></span>
 </span>
 
+<span id="kernel_selector_widget" class="nav pull-right">
+    <a href="#" class="dropdown-toggle" data-toggle="dropdown" id="current_kernel_spec">Python</a>
+    <ul id="kernel_selector" class="dropdown-menu">
+    </ul>
+</span>
+
 {% endblock %}