Separate the display from the models on the python side, creating a BaseWidget class.

Conflicts:
	IPython/html/widgets/widget.py

IPython/html/widgets/widget.py

@@ -1,441 +1,445 b''
 """Base Widget class.  Allows user to create widgets in the backend that render
 in the IPython notebook frontend.
 """
 #-----------------------------------------------------------------------------
 # 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 copy import copy
 from glob import glob
 import uuid
 import sys
 import os
 import inspect
 import types
 
 import IPython
 from IPython.kernel.comm import Comm
 from IPython.config import LoggingConfigurable
 from IPython.utils.traitlets import Unicode, Dict, List, Instance, Bool
 from IPython.display import Javascript, display
 from IPython.utils.py3compat import string_types
 
 #-----------------------------------------------------------------------------
 # Classes
 #-----------------------------------------------------------------------------
-class Widget(LoggingConfigurable):
+
+class BaseWidget(LoggingConfigurable):
 
     # Shared declarations (Class level)
-    _keys = []
+    _keys = List(Unicode, help="List of keys comprising the state of the model.")
+    _children_attr = List(Unicode, help="List of keys of children objects of the model.")
+    _children_lists_attr = List(Unicode, help="List of keys containing lists of children objects of the model.")
     widget_construction_callback = None
 
     def on_widget_constructed(callback):
         """Class method, registers a callback to be called when a widget is
         constructed.  The callback must have the following signature:
         callback(widget)"""
         Widget.widget_construction_callback = callback
 
     def _handle_widget_constructed(widget):
         """Class method, called when a widget is constructed."""
         if Widget.widget_construction_callback is not None and callable(Widget.widget_construction_callback):
             Widget.widget_construction_callback(widget)
 
     
 
     # Public declarations (Instance level)
     target_name = Unicode('widget', help="""Name of the backbone model 
         registered in the frontend to create and sync this widget with.""")
     default_view_name = Unicode(help="""Default view registered in the frontend
         to use to represent the widget.""")
-    parent = Instance('IPython.html.widgets.widget.Widget')
-    visible = Bool(True, help="Whether or not the widget is visible.")
-
-    def _parent_changed(self, name, old, new):
-        if self._displayed:
-            raise Exception('Parent cannot be set because widget has been displayed.')
-        elif new == self:
-            raise Exception('Parent cannot be set to self.')
-        else:
-
-            # Parent/child association
-            if new is not None and not self in new._children:
-                new._children.append(self)
-            if old is not None and self in old._children:
-                old._children.remove(self)                
 
     # Private/protected declarations
     _property_lock = (None, None) # Last updated (key, value) from the front-end.  Prevents echo.
-    _css = Dict() # Internal CSS property dict
     _displayed = False
-   
+    _comm = None
     
     def __init__(self, **kwargs):
         """Public constructor
-
-        Parameters
-        ----------
-        parent : Widget instance (optional)
-            Widget that this widget instance is child of.  When the widget is
-            displayed in the frontend, it's corresponding view will be made
-            child of the parent's view if the parent's view exists already.  If
-            the parent's view is displayed, it will automatically display this 
-            widget's default view as it's child.  The default view can be set
-            via the default_view_name property.
         """
-        self._children = []
         self._display_callbacks = []
         self._msg_callbacks = []
-        super(Widget, self).__init__(**kwargs)
+        super(BaseWidget, self).__init__(**kwargs)
                 
         # Register after init to allow default values to be specified
-        self.on_trait_change(self._handle_property_changed, self.keys)
-
+        # TODO: register three different handlers, one for each list, and abstract out the common parts
+        self.on_trait_change(self._handle_property_changed, self.keys+self._children_attr+self._children_lists_attr)
         Widget._handle_widget_constructed(self)
         
-        
     def __del__(self):
         """Object disposal"""
         self.close()
     
 
     def close(self):
         """Close method.  Closes the widget which closes the underlying comm.
         When the comm is closed, all of the widget views are automatically 
         removed from the frontend."""
         self._close_communication()
     
     
     # Properties      
-    def _get_keys(self):
-        keys = ['visible', '_css']
+    @property
+    def keys(self):
+        keys = ['_children_attr', '_children_lists_attr']
         keys.extend(self._keys)
         return keys
-    keys = property(_get_keys)
     
+    @property
+    def comm(self):
+        if self._comm is None:
+            self._open_communication()
+        return self._comm
     
     # Event handlers
     def _handle_msg(self, msg):
         """Called when a msg is recieved from the frontend"""
         data = msg['content']['data']
         method = data['method']
 
         # Handle backbone sync methods CREATE, PATCH, and UPDATE
         if method == 'backbone':
             if 'sync_method' in data and 'sync_data' in data:
                 sync_method = data['sync_method']
                 sync_data = data['sync_data']
                 self._handle_recieve_state(sync_data) # handles all methods
 
         # Handle a custom msg from the front-end
         elif method == 'custom':
             if 'custom_content' in data:
                 self._handle_custom_msg(data['custom_content'])
 
 
     def _handle_custom_msg(self, content):
         """Called when a custom msg is recieved."""
         for handler in self._msg_callbacks:
             if callable(handler):
                 argspec = inspect.getargspec(handler)
                 nargs = len(argspec[0])
 
                 # Bound methods have an additional 'self' argument
                 if isinstance(handler, types.MethodType):
                     nargs -= 1
 
                 # Call the callback
                 if nargs == 1:
                     handler(content)
                 elif nargs == 2:
                     handler(self, content)
                 else:
                     raise TypeError('Widget msg callback must ' \
                         'accept 1 or 2 arguments, not %d.' % nargs)
     
     
     def _handle_recieve_state(self, sync_data):
         """Called when a state is recieved from the frontend."""
         # Use _keys instead of keys - Don't get retrieve the css from the client side.
         for name in self._keys:
             if name in sync_data:
                 try:
                     self._property_lock = (name, sync_data[name])
                     setattr(self, name, sync_data[name])
                 finally:
                     self._property_lock = (None, None)
     
     
     def _handle_property_changed(self, name, old, new):
         """Called when a proeprty has been changed."""
         # Make sure this isn't information that the front-end just sent us.
         if self._property_lock[0] != name and self._property_lock[1] != new:
             # Send new state to frontend
             self.send_state(key=name)
 
-
     def _handle_displayed(self, **kwargs):
         """Called when a view has been displayed for this widget instance
 
         Parameters
         ----------
         [view_name]: unicode (optional kwarg)
             Name of the view that was displayed."""
         for handler in self._display_callbacks:
             if callable(handler):
                 argspec = inspect.getargspec(handler)
                 nargs = len(argspec[0])
 
                 # Bound methods have an additional 'self' argument
                 if isinstance(handler, types.MethodType):
                     nargs -= 1
 
                 # Call the callback
                 if nargs == 0:
                     handler()
                 elif nargs == 1:
                     handler(self)
                 elif nargs == 2:
                     handler(self, kwargs.get('view_name', None))
                 else:
                     handler(self, **kwargs)
     
-    
     # Public methods
     def send_state(self, key=None):
         """Sends the widget state, or a piece of it, to the frontend.
 
         Parameters
         ----------
         key : unicode (optional)
             A single property's name to sync with the frontend.
         """
-        state = {}
-
-        # If a key is provided, just send the state of that key.
-        keys = []
-        if key is None:
-            keys.extend(self.keys)
-        else:
-            keys.append(key)
-        for key in self.keys:
-            try:
-                state[key] = getattr(self, key)
-            except Exception as e:
-                pass # Eat errors, nom nom nom
         self._send({"method": "update",
-                        "state": state})
+                    "state": self.get_state()})
 
-
-    def get_css(self, key, selector=""):
-        """Get a CSS property of the widget.  Note, this function does not 
-        actually request the CSS from the front-end;  Only properties that have 
-        been set with set_css can be read.
+    def get_state(self, key=None)
+        """Gets the widget state, or a piece of it.
 
         Parameters
         ----------
-        key: unicode
-            CSS key
-        selector: unicode (optional)
-            JQuery selector used when the CSS key/value was set.
-        """
-        if selector in self._css and key in self._css[selector]:
-            return self._css[selector][key]
-        else:
-            return None
-
-
-    def set_css(self, *args, **kwargs):
-        """Set one or more CSS properties of the widget (shared among all of the 
-        views).  This function has two signatures:
-        - set_css(css_dict, [selector=''])
-        - set_css(key, value, [selector=''])
-
-        Parameters
-        ----------
-        css_dict : dict
-            CSS key/value pairs to apply
-        key: unicode
-            CSS key
-        value
-            CSS value
-        selector: unicode (optional)
-            JQuery selector to use to apply the CSS key/value.
+        key : unicode (optional)
+            A single property's name to get.
         """
-        selector = kwargs.get('selector', '')
+        state = {}
 
-        # Signature 1: set_css(css_dict, [selector=''])
-        if len(args) == 1:
-            if isinstance(args[0], dict):
-                for (key, value) in args[0].items():
-                    self.set_css(key, value, selector=selector)
+        # If a key is provided, just send the state of that key.
+        if key is None:
+            keys = self.keys[:]
+            children_attr = self._children_attr[:]
+            children_lists_attr = self._children_lists_attr[:]
             else:
-                raise Exception('css_dict must be a dict.')
-
-        # Signature 2: set_css(key, value, [selector=''])
-        elif len(args) == 2 or len(args) == 3:
-
-            # Selector can be a positional arg if it's the 3rd value
-            if len(args) == 3:
-                selector = args[2]
-            if selector not in self._css:
-                self._css[selector] = {}
-                
-            # Only update the property if it has changed.
-            key = args[0]
-            value = args[1]
-            if not (key in self._css[selector] and value in self._css[selector][key]):
-                self._css[selector][key] = value
-                self.send_state('_css') # Send new state to client.
+            keys = []
+            children_attr = []
+            children_lists_attr = []
+            if key in self._children_attr:
+                children_attr.append(key)
+            elif key in self._children_lists_attr:
+                children_lists_attr.append(key)
         else:
-            raise Exception('set_css only accepts 1-3 arguments')
-
-
-    def add_class(self, class_name, selector=""):
-        """Add class[es] to a DOM element
-
-        Parameters
-        ----------
-        class_name: unicode
-            Class name(s) to add to the DOM element(s).  Multiple class names 
-            must be space separated.
-        selector: unicode (optional)
-            JQuery selector to select the DOM element(s) that the class(es) will 
-            be added to.
-        """
-        self._send({"method": "add_class",
-                        "class_list": class_name,
-                        "selector": selector})
-
-
-    def remove_class(self, class_name, selector=""):
-        """Remove class[es] from a DOM element
-
-        Parameters
-        ----------
-        class_name: unicode
-            Class name(s) to remove from  the DOM element(s).  Multiple class 
-            names must be space separated.
-        selector: unicode (optional)
-            JQuery selector to select the DOM element(s) that the class(es) will 
-            be removed from.
-        """
-        self._send({"method": "remove_class",
-                        "class_list": class_name,
-                        "selector": selector})
+                keys.append(key)
+        for k in keys:
+            state[k] = getattr(self, k)
+        for k in children_attr:
+            # automatically create models on the browser side if they aren't already created
+            state[k] = getattr(self, k).comm.comm_id
+        for k in children_lists_attr:
+            # automatically create models on the browser side if they aren't already created
+            state[k] = [i.comm.comm_id for i in getattr(self, k)]
+        return state
 
 
     def send(self, content):
         """Sends a custom msg to the widget model in the front-end.
 
         Parameters
         ----------
         content : dict
             Content of the message to send.
         """
         self._send({"method": "custom",
                         "custom_content": content})
 
 
     def on_msg(self, callback, remove=False):
         """Register a callback for when a custom msg is recieved from the front-end
 
         Parameters
         ----------
         callback: method handler
             Can have a signature of:
             - callback(content)
             - callback(sender, content)
         remove: bool
             True if the callback should be unregistered."""
         if remove and callback in self._msg_callbacks:
             self._msg_callbacks.remove(callback)
         elif not remove and not callback in self._msg_callbacks:
             self._msg_callbacks.append(callback)
 
 
     def on_displayed(self, callback, remove=False):
         """Register a callback to be called when the widget has been displayed
 
         Parameters
         ----------
         callback: method handler
             Can have a signature of:
             - callback()
             - callback(sender)
             - callback(sender, view_name)
             - callback(sender, **kwargs)
               kwargs from display call passed through without modification.
         remove: bool
             True if the callback should be unregistered."""
         if remove and callback in self._display_callbacks:
             self._display_callbacks.remove(callback)
         elif not remove and not callback in self._display_callbacks:
             self._display_callbacks.append(callback)
 
 
     # Support methods
     def _repr_widget_(self, **kwargs):
         """Function that is called when `IPython.display.display` is called on
         the widget.
 
         Parameters
         ----------
         view_name: unicode (optional)
             View to display in the frontend.  Overrides default_view_name."""
         view_name = kwargs.get('view_name', self.default_view_name)
         
         # Create a communication.
         self._open_communication()
         
         # Make sure model is syncronized
         self.send_state()
             
         # Show view.
-        if self.parent is None or self.parent._comm is None:
             self._send({"method": "display", "view_name": view_name})
-        else:
-            self._send({"method": "display", 
-                            "view_name": view_name,
-                            "parent": self.parent._comm.comm_id})
-        self._handle_displayed(**kwargs)
         self._displayed = True
-
-        # Now display children if any.
-        for child in self._children:
-            if child != self:
-                child._repr_widget_()
-        return None
+        self._handle_displayed(**kwargs)
 
 
     def _open_communication(self):
         """Opens a communication with the front-end."""
         # Create a comm.
         if not hasattr(self, '_comm') or self._comm is None:
             self._comm = Comm(target_name=self.target_name)
             self._comm.on_msg(self._handle_msg)
             self._comm.on_close(self._close_communication)
 
 
     def _close_communication(self):
         """Closes a communication with the front-end."""
         if hasattr(self, '_comm') and self._comm is not None:
             try:
                 self._comm.close()
             finally:
                 self._comm = None
 
 
     def _send(self, msg):
         """Sends a message to the model in the front-end"""
-        if hasattr(self, '_comm') and self._comm is not None:
+        if self._comm is not None:
             self._comm.send(msg)
             return True
         else:
             return False
+
+class Widget(BaseWidget):
+
+    _children = List(Instance('IPython.html.widgets.widget.Widget'))
+    _children_lists_attr = List(Unicode, ['_children'])
+    visible = Bool(True, help="Whether or not the widget is visible.")
+
+    # Private/protected declarations
+    _css = Dict() # Internal CSS property dict
+
+    # Properties
+    @property
+    def keys(self):
+        keys = ['visible', '_css']
+        keys.extend(super(Widget, self).keys)
+        return keys
+
+    def get_css(self, key, selector=""):
+        """Get a CSS property of the widget.  Note, this function does not
+        actually request the CSS from the front-end;  Only properties that have
+        been set with set_css can be read.
+
+        Parameters
+        ----------
+        key: unicode
+            CSS key
+        selector: unicode (optional)
+            JQuery selector used when the CSS key/value was set.
+        """
+        if selector in self._css and key in self._css[selector]:
+            return self._css[selector][key]
+        else:
+            return None
+
+
+    def set_css(self, *args, **kwargs):
+        """Set one or more CSS properties of the widget (shared among all of the
+        views).  This function has two signatures:
+        - set_css(css_dict, [selector=''])
+        - set_css(key, value, [selector=''])
+
+        Parameters
+        ----------
+        css_dict : dict
+            CSS key/value pairs to apply
+        key: unicode
+            CSS key
+        value
+            CSS value
+        selector: unicode (optional)
+            JQuery selector to use to apply the CSS key/value.
+        """
+        selector = kwargs.get('selector', '')
+
+        # Signature 1: set_css(css_dict, [selector=''])
+        if len(args) == 1:
+            if isinstance(args[0], dict):
+                for (key, value) in args[0].items():
+                    self.set_css(key, value, selector=selector)
+            else:
+                raise Exception('css_dict must be a dict.')
+
+        # Signature 2: set_css(key, value, [selector=''])
+        elif len(args) == 2 or len(args) == 3:
+
+            # Selector can be a positional arg if it's the 3rd value
+            if len(args) == 3:
+                selector = args[2]
+            if selector not in self._css:
+                self._css[selector] = {}
+
+            # Only update the property if it has changed.
+            key = args[0]
+            value = args[1]
+            if not (key in self._css[selector] and value in self._css[selector][key]):
+                self._css[selector][key] = value
+                self.send_state('_css') # Send new state to client.
+        else:
+            raise Exception('set_css only accepts 1-3 arguments')
+
+
+    def add_class(self, class_name, selector=""):
+        """Add class[es] to a DOM element
+
+        Parameters
+        ----------
+        class_name: unicode
+            Class name(s) to add to the DOM element(s).  Multiple class names
+            must be space separated.
+        selector: unicode (optional)
+            JQuery selector to select the DOM element(s) that the class(es) will
+            be added to.
+        """
+        self._send({"method": "add_class",
+                        "class_list": class_name,
+                        "selector": selector})
+
+
+    def remove_class(self, class_name, selector=""):
+        """Remove class[es] from a DOM element
+
+        Parameters
+        ----------
+        class_name: unicode
+            Class name(s) to remove from  the DOM element(s).  Multiple class
+            names must be space separated.
+        selector: unicode (optional)
+            JQuery selector to select the DOM element(s) that the class(es) will
+            be removed from.
+        """
+        self._send({"method": "remove_class",
+                        "class_list": class_name,
+                        "selector": selector})