Fix param.Action (#9).

examples/user_guide/Bokeh_App.ipynb

@@ -19,12 +19,11 @@
     "\n",
     "import param\n",
     "import datetime as dt\n",
-    "\n",
-    "def hello(x, **kwargs):\n",
-    "    print(\"Hello %s\" % x)\n",
     "    \n",
     "class Example(param.Parameterized):\n",
     "    \"\"\"An example Parameterized class\"\"\"\n",
+    "    timestamps = []\n",
+    "    \n",
     "    x                       = param.Parameter(default=3.14,doc=\"X position\")\n",
     "    y                       = param.Parameter(default=\"Not editable\",constant=True)\n",
     "    string_value            = param.String(default=\"str\",doc=\"A string\")\n",
@@ -46,7 +45,8 @@
     "    int_list                = param.ListSelector(default=[3,5], objects=[1,3,5,7,9],precedence=0.5)\n",
     "    single_file             = param.FileSelector(path='../../*/*.py*',precedence=0.5)\n",
     "    multiple_files          = param.MultiFileSelector(path='../../*/*.py?',precedence=0.5)\n",
-    "    #msg                     = param.Action(hello, doc=\"\"\"Print a message.\"\"\",precedence=0.7)\n"
+    "    record_timestamp        = param.Action(lambda x: x.timestamps.append(dt.datetime.now()), \n",
+    "                                           doc=\"\"\"Record timestamp.\"\"\",precedence=0.7)\n"
    ]
   },
   {

examples/user_guide/Introduction.ipynb

@@ -20,9 +20,6 @@
     "import param\n",
     "import datetime as dt\n",
     "\n",
-    "def hello(x, **kwargs):\n",
-    "    print(\"Hello %s\" % x)\n",
-    "    \n",
     "class BaseClass(param.Parameterized):\n",
     "    x                       = param.Parameter(default=3.14,doc=\"X position\")\n",
     "    y                       = param.Parameter(default=\"Not editable\",constant=True)\n",
@@ -39,6 +36,8 @@
     "    \n",
     "class Example(BaseClass):\n",
     "    \"\"\"An example Parameterized class\"\"\"\n",
+    "    timestamps = []\n",
+    "\n",
     "    boolean                 = param.Boolean(True, doc=\"A sample Boolean parameter\")\n",
     "    color                   = param.Color(default='#FFFFFF')\n",
     "    date                    = param.Date(dt.datetime(2017, 1, 1),\n",
@@ -48,7 +47,8 @@
     "    int_list                = param.ListSelector(default=[3,5], objects=[1,3,5,7,9],precedence=0.5)\n",
     "    single_file             = param.FileSelector(path='../../*/*.py*',precedence=0.5)\n",
     "    multiple_files          = param.MultiFileSelector(path='../../*/*.py?',precedence=0.5)\n",
-    "    #msg                     = param.Action(hello, doc=\"\"\"Print a message.\"\"\",precedence=0.7)\n",
+    "    record_timestamp        = param.Action(lambda x: x.timestamps.append(dt.datetime.now()), \n",
+    "                                           doc=\"\"\"Record timestamp.\"\"\",precedence=0.7)\n",
     "    \n",
     "Example.num_int"
    ]
@@ -124,6 +124,22 @@
     "Example.num_int"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Example.timestamps records the times you pressed the \"record timestamp\" button."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "Example.timestamps"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": null,

parambokeh/__init__.py

@@ -174,6 +174,9 @@ def __call__(self, parameterized, doc=None, plots=[], **params):
     def on_msg(self, msg):
         p_name = msg['p_name']
         p_obj = self.parameterized.params(p_name)
+        if isinstance(p_obj, param.Action):
+            getattr(self.parameterized, p_name)(self.parameterized)
+            return
         w = self._widgets[p_name]
         self._queue.append((w, p_obj, p_name, None, None, msg['value']))
         self.change_event()
@@ -258,10 +261,6 @@ def _make_widget(self, p_name):
         value = getattr(self.parameterized, p_name)
 
         kw = dict(value=value)
-        if isinstance(p_obj, param.Action):
-            def action_cb(button):
-                getattr(self.parameterized, p_name)(self.parameterized)
-            kw['value'] = action_cb
 
         kw['title'] = p_name
 
@@ -289,12 +288,17 @@ def action_cb(button):
 
         if hasattr(p_obj, 'callbacks'):
             p_obj.callbacks[id(self.parameterized)] = functools.partial(self._update_trait, p_name)
-        elif isinstance(w, (Button, Toggle)):
+        elif isinstance(w, Toggle):
             if self.p.mode in ['server', 'raw']:
                 w.on_change('active', functools.partial(self.on_change, w, p_obj, p_name))
             else:
                 js_callback = self._get_customjs('active', p_name)
                 w.js_on_change('active', js_callback)
+        elif isinstance(w, Button):
+            if self.p.mode in ['server', 'raw']:
+                w.on_click(functools.partial(value,self.parameterized))
+            else:
+                w.js_on_click(self._get_customjs('active', p_name))
         elif not p_obj.constant:
             if self.p.mode in ['server', 'raw']:
                 cb = functools.partial(self.on_change, w, p_obj, p_name)

parambokeh/comms.py

@@ -225,6 +225,10 @@ def _handle_msg(self, msg):
                 with StandardOutput() as stdout:
                     self._on_msg(msg)
         except Exception as e:
+            # TODO: isn't this cutting out info needed to understand what's gone wrong?
+            # Since it's only going to the js console, maybe we could just show everything
+            # (error = traceback.format_exc() or something like that)? Separately we do need a mechanism
+            # to report reasonable messages to users, though.
             frame =traceback.extract_tb(sys.exc_info()[2])[-2]
             fname,lineno,fn,text = frame
             error_kwargs = dict(type=type(e).__name__, fn=fn, fname=fname,

parambokeh/widgets.py

@@ -31,10 +31,8 @@ def ToggleWidget(*args, **kw):
 
 def ButtonWidget(*args, **kw):
     kw['label'] = kw.pop('title')
-    cb = kw.pop('value')
-    button = Button(*args, **kw)
-    button.on_click(cb)
-    return button
+    kw.pop('value') # button doesn't have value (value attached as click callback)
+    return Button(*args, **kw)
 
 # TODO: make a composite box/slider widget; slider only appears if
 # there's a range.