Merge pull request #5067 from minrk/widget-error

show traceback in widget handlers

IPython/html/widgets/interaction.py

@@ -1,251 +1,259 b''
 """Interact with functions using widgets."""
 
 #-----------------------------------------------------------------------------
 # 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 __future__ import print_function
 
 try:  # Python >= 3.3
     from inspect import signature, Parameter
 except ImportError:
     from IPython.utils.signatures import signature, Parameter
 from inspect import getcallargs
 
+from IPython.core.getipython import get_ipython
 from IPython.html.widgets import (Widget, TextWidget,
     FloatSliderWidget, IntSliderWidget, CheckboxWidget, DropdownWidget,
     ContainerWidget, DOMWidget)
 from IPython.display import display, clear_output
 from IPython.utils.py3compat import string_types, unicode_type
 from IPython.utils.traitlets import HasTraits, Any, Unicode
 
 #-----------------------------------------------------------------------------
 # Classes and Functions
 #-----------------------------------------------------------------------------
 
 
 def _matches(o, pattern):
     """Match a pattern of types in a sequence."""
     if not len(o) == len(pattern):
         return False
     comps = zip(o,pattern)
     return all(isinstance(obj,kind) for obj,kind in comps)
 
 
 def _get_min_max_value(min, max, value=None, step=None):
     """Return min, max, value given input values with possible None."""
     if value is None:
         if not max > min:
             raise ValueError('max must be greater than min: (min={0}, max={1})'.format(min, max))
         value = min + abs(min-max)/2
         value = type(min)(value)
     elif min is None and max is None:
         if value == 0.0:
             min, max, value = 0.0, 1.0, 0.5
         elif value == 0:
             min, max, value = 0, 1, 0
         elif isinstance(value, (int, float)):
             min, max = (-value, 3*value) if value > 0 else (3*value, -value)
         else:
             raise TypeError('expected a number, got: %r' % value)
     else:
         raise ValueError('unable to infer range, value from: ({0}, {1}, {2})'.format(min, max, value))
     if step is not None:
         # ensure value is on a step
         r = (value - min) % step
         value = value - r
     return min, max, value
 
 def _widget_abbrev_single_value(o):
     """Make widgets from single values, which can be used as parameter defaults."""
     if isinstance(o, string_types):
         return TextWidget(value=unicode_type(o))
     elif isinstance(o, dict):
         return DropdownWidget(values=o)
     elif isinstance(o, bool):
         return CheckboxWidget(value=o)
     elif isinstance(o, float):
         min, max, value = _get_min_max_value(None, None, o)
         return FloatSliderWidget(value=o, min=min, max=max)
     elif isinstance(o, int):
         min, max, value = _get_min_max_value(None, None, o)
         return IntSliderWidget(value=o, min=min, max=max)
     else:
         return None
 
 def _widget_abbrev(o):
     """Make widgets from abbreviations: single values, lists or tuples."""
     float_or_int = (float, int)
     if isinstance(o, (list, tuple)):
         if o and all(isinstance(x, string_types) for x in o):
             return DropdownWidget(values=[unicode_type(k) for k in o])
         elif _matches(o, (float_or_int, float_or_int)):
             min, max, value = _get_min_max_value(o[0], o[1])
             if all(isinstance(_, int) for _ in o):
                 cls = IntSliderWidget
             else:
                 cls = FloatSliderWidget
             return cls(value=value, min=min, max=max)
         elif _matches(o, (float_or_int, float_or_int, float_or_int)):
             step = o[2]
             if step <= 0:
                 raise ValueError("step must be >= 0, not %r" % step)
             min, max, value = _get_min_max_value(o[0], o[1], step=step)
             if all(isinstance(_, int) for _ in o):
                 cls = IntSliderWidget
             else:
                 cls = FloatSliderWidget
             return cls(value=value, min=min, max=max, step=step)
     else:
         return _widget_abbrev_single_value(o)
 
 def _widget_from_abbrev(abbrev):
     """Build a Widget intstance given an abbreviation or Widget."""
     if isinstance(abbrev, Widget) or isinstance(abbrev, fixed):
         return abbrev
     
     widget = _widget_abbrev(abbrev)
     if widget is None:
         raise ValueError("%r cannot be transformed to a Widget" % (abbrev,))
     return widget
 
 def _yield_abbreviations_for_parameter(param, kwargs):
     """Get an abbreviation for a function parameter."""
     name = param.name
     kind = param.kind
     ann = param.annotation
     default = param.default
     empty = Parameter.empty
     not_found = (None, None)
     if kind == Parameter.POSITIONAL_OR_KEYWORD:
         if name in kwargs:
             yield name, kwargs.pop(name)
         elif ann is not empty:
             if default is empty:
                 yield name, ann
             else:
                 yield name, ann
         elif default is not empty:
             yield name, default
         else:
             yield not_found
     elif kind == Parameter.KEYWORD_ONLY:
         if name in kwargs:
             yield name, kwargs.pop(name)
         elif ann is not empty:
             yield name, ann
         elif default is not empty:
             yield name, default
         else:
             yield not_found
     elif kind == Parameter.VAR_KEYWORD:
         # In this case name=kwargs and we yield the items in kwargs with their keys.
         for k, v in kwargs.copy().items():
             kwargs.pop(k)
             yield k, v
 
 def _find_abbreviations(f, kwargs):
     """Find the abbreviations for a function and kwargs passed to interact."""
     new_kwargs = []
     for param in signature(f).parameters.values():
         for name, value in _yield_abbreviations_for_parameter(param, kwargs):
             if value is None:
                 raise ValueError('cannot find widget or abbreviation for argument: {!r}'.format(name))
             new_kwargs.append((name, value))
     return new_kwargs
 
 def _widgets_from_abbreviations(seq):
     """Given a sequence of (name, abbrev) tuples, return a sequence of Widgets."""
     result = []
     for name, abbrev in seq:
         widget = _widget_from_abbrev(abbrev)
         widget.description = name
         result.append(widget)
     return result
 
 def interactive(__interact_f, **kwargs):
     """Build a group of widgets to interact with a function."""
     f = __interact_f
     co = kwargs.pop('clear_output', True)
     kwargs_widgets = []
     container = ContainerWidget()
     container.result = None
     container.args = []
     container.kwargs = dict()
     kwargs = kwargs.copy()
 
     new_kwargs = _find_abbreviations(f, kwargs)
     # Before we proceed, let's make sure that the user has passed a set of args+kwargs
     # that will lead to a valid call of the function. This protects against unspecified
     # and doubly-specified arguments.
     getcallargs(f, **{n:v for n,v in new_kwargs})
     # Now build the widgets from the abbreviations.
     kwargs_widgets.extend(_widgets_from_abbreviations(new_kwargs))
     kwargs_widgets.extend(_widgets_from_abbreviations(sorted(kwargs.items(), key = lambda x: x[0])))
 
     # This has to be done as an assignment, not using container.children.append,
     # so that traitlets notices the update. We skip any objects (such as fixed) that
     # are not DOMWidgets.
     c = [w for w in kwargs_widgets if isinstance(w, DOMWidget)]
     container.children = c
 
     # Build the callback
     def call_f(name, old, new):
         container.kwargs = {}
         for widget in kwargs_widgets:
             value = widget.value
             container.kwargs[widget.description] = value
         if co:
             clear_output(wait=True)
-        container.result = f(**container.kwargs)
+        try:
+            container.result = f(**container.kwargs)
+        except Exception as e:
+            ip = get_ipython()
+            if ip is None:
+                container.log.warn("Exception in interact callback: %s", e, exc_info=True)
+            else:
+                ip.showtraceback()
 
     # Wire up the widgets
     for widget in kwargs_widgets:
         widget.on_trait_change(call_f, 'value')
 
     container.on_displayed(lambda _: call_f(None, None, None))
 
     return container
 
 def interact(__interact_f=None, **kwargs):
     """interact(f, **kwargs)
     
     Interact with a function using widgets."""
     # positional arg support in: https://gist.github.com/8851331
     if __interact_f is not None:
         # This branch handles the cases:
         # 1. interact(f, **kwargs)
         # 2. @interact
         #    def f(*args, **kwargs):
         #        ...
         f = __interact_f
         w = interactive(f, **kwargs)
         f.widget = w
         display(w)
         return f
     else:
         # This branch handles the case:
         # @interact(a=30, b=40)
         # def f(*args, **kwargs):
         #     ...
         def dec(f):
             w = interactive(f, **kwargs)
             f.widget = w
             display(w)
             return f
         return dec
 
 class fixed(HasTraits):
     """A pseudo-widget whose value is fixed and never synced to the client."""
     value = Any(help="Any Python object")
     description = Unicode('', help="Any Python object")
     def __init__(self, value, **kwargs):
         super(fixed, self).__init__(value=value, **kwargs)

IPython/html/widgets/widget.py

@@ -1,423 +1,441 b''
 """Base Widget class.  Allows user to create widgets in the back-end that render
 in the IPython notebook front-end.
 """
 #-----------------------------------------------------------------------------
 # 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 contextlib import contextmanager
 
+from IPython.core.getipython import get_ipython
 from IPython.kernel.comm import Comm
 from IPython.config import LoggingConfigurable
 from IPython.utils.traitlets import Unicode, Dict, Instance, Bool, List, Tuple
 from IPython.utils.py3compat import string_types
 
 #-----------------------------------------------------------------------------
 # Classes
 #-----------------------------------------------------------------------------
 class CallbackDispatcher(LoggingConfigurable):
     """A structure for registering and running callbacks"""
     callbacks = List()
     
     def __call__(self, *args, **kwargs):
         """Call all of the registered callbacks."""
         value = None
         for callback in self.callbacks:
             try:
                 local_value = callback(*args, **kwargs)
             except Exception as e:
-                self.log.warn("Exception in callback %s: %s", callback, e)
+                ip = get_ipython()
+                if ip is None:
+                    self.log.warn("Exception in callback %s: %s", callback, e, exc_info=True)
+                else:
+                    ip.showtraceback()
             else:
                 value = local_value if local_value is not None else value
         return value
 
     def register_callback(self, callback, remove=False):
         """(Un)Register a callback
 
         Parameters
         ----------
         callback: method handle
             Method to be registered or unregistered.
         remove=False: bool
             Whether to unregister the callback."""
         
         # (Un)Register the callback.
         if remove and callback in self.callbacks:
             self.callbacks.remove(callback)
         elif not remove and callback not in self.callbacks:
             self.callbacks.append(callback)
 
+def _show_traceback(method):
+    """decorator for showing tracebacks in IPython"""
+    def m(self, *args, **kwargs):
+        try:
+            return(method(self, *args, **kwargs))
+        except Exception as e:
+            ip = get_ipython()
+            if ip is None:
+                self.log.warn("Exception in widget method %s: %s", method, e, exc_info=True)
+            else:
+                ip.showtraceback()
+    return m
 
 class Widget(LoggingConfigurable):
     #-------------------------------------------------------------------------
     # Class attributes
     #-------------------------------------------------------------------------
     _widget_construction_callback = None
     widgets = {}
 
     @staticmethod
     def on_widget_constructed(callback):
         """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
 
     @staticmethod
     def _call_widget_constructed(widget):
         """Static 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)
 
     #-------------------------------------------------------------------------
     # Traits
     #-------------------------------------------------------------------------
     _model_name = Unicode('WidgetModel', help="""Name of the backbone model 
         registered in the front-end to create and sync this widget with.""")
     _view_name = Unicode(help="""Default view registered in the front-end
         to use to represent the widget.""", sync=True)
     _comm = Instance('IPython.kernel.comm.Comm')
     
     closed = Bool(False)
     
     keys = List()
     def _keys_default(self):
         return [name for name in self.traits(sync=True)]
     
     _property_lock = Tuple((None, None))
     
     _display_callbacks = Instance(CallbackDispatcher, ())
     _msg_callbacks = Instance(CallbackDispatcher, ())
     
     #-------------------------------------------------------------------------
     # (Con/de)structor
     #-------------------------------------------------------------------------
     def __init__(self, **kwargs):
         """Public constructor"""
         super(Widget, self).__init__(**kwargs)
 
         self.on_trait_change(self._handle_property_changed, self.keys)
         Widget._call_widget_constructed(self)
 
     def __del__(self):
         """Object disposal"""
         self.close()
 
     #-------------------------------------------------------------------------
     # Properties
     #-------------------------------------------------------------------------
 
     @property
     def comm(self):
         """Gets the Comm associated with this widget.
 
         If a Comm doesn't exist yet, a Comm will be created automagically."""
         if self._comm is None:
             # Create a comm.
             self._comm = Comm(target_name=self._model_name)
             self._comm.on_msg(self._handle_msg)
             self._comm.on_close(self._close)
             Widget.widgets[self.model_id] = self
 
             # first update
             self.send_state()
         return self._comm
     
     @property
     def model_id(self):
         """Gets the model id of this widget.
 
         If a Comm doesn't exist yet, a Comm will be created automagically."""
         return self.comm.comm_id
 
     #-------------------------------------------------------------------------
     # Methods
     #-------------------------------------------------------------------------
     def _close(self):
         """Private close - cleanup objects, registry entries"""
         del Widget.widgets[self.model_id]
         self._comm = None
         self.closed = True
 
     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 front-end."""
         if not self.closed:
             self._comm.close()
             self._close()
 
     def send_state(self, key=None):
         """Sends the widget state, or a piece of it, to the front-end.
 
         Parameters
         ----------
         key : unicode (optional)
             A single property's name to sync with the front-end.
         """
         self._send({
             "method" : "update",
             "state"  : self.get_state()
         })
 
     def get_state(self, key=None):
         """Gets the widget state, or a piece of it.
 
         Parameters
         ----------
         key : unicode (optional)
             A single property's name to get.
         """
         keys = self.keys if key is None else [key]
         return {k: self._pack_widgets(getattr(self, k)) for k in keys} 
 
     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", "content": content})
 
     def on_msg(self, callback, remove=False):
         """(Un)Register a custom msg receive callback.
 
         Parameters
         ----------
         callback: callable
             callback will be passed two arguments when a message arrives::
             
                 callback(widget, content)
             
         remove: bool
             True if the callback should be unregistered."""
         self._msg_callbacks.register_callback(callback, remove=remove)
 
     def on_displayed(self, callback, remove=False):
         """(Un)Register a widget displayed callback.
 
         Parameters
         ----------
         callback: method handler
             Must have a signature of::
             
                 callback(widget, **kwargs)
             
             kwargs from display are passed through without modification.
         remove: bool
             True if the callback should be unregistered."""
         self._display_callbacks.register_callback(callback, remove=remove)
 
     #-------------------------------------------------------------------------
     # Support methods
     #-------------------------------------------------------------------------
     @contextmanager
     def _lock_property(self, key, value):
         """Lock a property-value pair.
 
         NOTE: This, in addition to the single lock for all state changes, is 
         flawed.  In the future we may want to look into buffering state changes 
         back to the front-end."""
         self._property_lock = (key, value)
         try:
             yield
         finally:
             self._property_lock = (None, None)
 
     def _should_send_property(self, key, value):
         """Check the property lock (property_lock)"""
         return key != self._property_lock[0] or \
         value != self._property_lock[1]
     
     # Event handlers
+    @_show_traceback
     def _handle_msg(self, msg):
         """Called when a msg is received from the front-end"""
         data = msg['content']['data']
         method = data['method']
         if not method in ['backbone', 'custom']:
             self.log.error('Unknown front-end to back-end widget msg with method "%s"' % method)
 
         # Handle backbone sync methods CREATE, PATCH, and UPDATE all in one.
         if method == 'backbone' and 'sync_data' in data:
             sync_data = data['sync_data']
             self._handle_receive_state(sync_data) # handles all methods
 
         # Handle a custom msg from the front-end
         elif method == 'custom':
             if 'content' in data:
                 self._handle_custom_msg(data['content'])
 
     def _handle_receive_state(self, sync_data):
         """Called when a state is received from the front-end."""
         for name in self.keys:
             if name in sync_data:
                 value = self._unpack_widgets(sync_data[name])
                 with self._lock_property(name, value):
                     setattr(self, name, value)
 
     def _handle_custom_msg(self, content):
         """Called when a custom msg is received."""
         self._msg_callbacks(self, content)
 
     def _handle_property_changed(self, name, old, new):
         """Called when a property has been changed."""
         # Make sure this isn't information that the front-end just sent us.
         if self._should_send_property(name, new):
             # Send new state to front-end
             self.send_state(key=name)
 
     def _handle_displayed(self, **kwargs):
         """Called when a view has been displayed for this widget instance"""
         self._display_callbacks(self, **kwargs)
 
     def _pack_widgets(self, x):
         """Recursively converts all widget instances to model id strings.
 
         Children widgets will be stored and transmitted to the front-end by 
         their model ids.  Return value must be JSON-able."""
         if isinstance(x, dict):
             return {k: self._pack_widgets(v) for k, v in x.items()}
         elif isinstance(x, list):
             return [self._pack_widgets(v) for v in x]
         elif isinstance(x, Widget):
             return x.model_id
         else:
             return x # Value must be JSON-able
 
     def _unpack_widgets(self, x):
         """Recursively converts all model id strings to widget instances.
 
         Children widgets will be stored and transmitted to the front-end by 
         their model ids."""
         if isinstance(x, dict):
             return {k: self._unpack_widgets(v) for k, v in x.items()}
         elif isinstance(x, list):
             return [self._unpack_widgets(v) for v in x]
         elif isinstance(x, string_types):
             return x if x not in Widget.widgets else Widget.widgets[x]
         else:
             return x
 
     def _ipython_display_(self, **kwargs):
         """Called when `IPython.display.display` is called on the widget."""
         # Show view.  By sending a display message, the comm is opened and the
         # initial state is sent.
         self._send({"method": "display"})
         self._handle_displayed(**kwargs)
 
     def _send(self, msg):
         """Sends a message to the model in the front-end."""
         self.comm.send(msg)
 
 
 class DOMWidget(Widget):
     visible = Bool(True, help="Whether the widget is visible.", sync=True)
     _css = Dict(sync=True) # Internal CSS property dict
 
     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, dict_or_key, value=None, selector=''):
         """Set one or more CSS properties of the widget.
 
         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, kwarg only)
             JQuery selector to use to apply the CSS key/value.  If no selector 
             is provided, an empty selector is used.  An empty selector makes the 
             front-end try to apply the css to a default element.  The default
             element is an attribute unique to each view, which is a DOM element
             of the view that should be styled with common CSS (see 
             `$el_to_style` in the Javascript code).
         """
         if not selector in self._css:
             self._css[selector] = {}
         my_css = self._css[selector]
         
         if value is None:
             css_dict = dict_or_key
         else:
             css_dict = {dict_or_key: value}
         
         for (key, value) in css_dict.items():
             if not (key in my_css and value == my_css[key]):
                 my_css[key] = value
         self.send_state('_css')
 
     def add_class(self, class_names, selector=""):
         """Add class[es] to a DOM element.
 
         Parameters
         ----------
         class_names: unicode or list
             Class name(s) to add to the DOM element(s).
         selector: unicode (optional)
             JQuery selector to select the DOM element(s) that the class(es) will
             be added to.
         """
         class_list = class_names
         if isinstance(class_list, list):
             class_list = ' '.join(class_list)
 
         self.send({
             "msg_type"   : "add_class",
             "class_list" : class_list,
             "selector"   : selector
         })
 
     def remove_class(self, class_names, selector=""):
         """Remove class[es] from a DOM element.
 
         Parameters
         ----------
         class_names: unicode or list
             Class name(s) to remove from  the DOM element(s).
         selector: unicode (optional)
             JQuery selector to select the DOM element(s) that the class(es) will
             be removed from.
         """
         class_list = class_names
         if isinstance(class_list, list):
             class_list = ' '.join(class_list)
 
         self.send({
             "msg_type"   : "remove_class",
             "class_list" : class_list,
             "selector"   : selector,
         })