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handle undefined or closed zmq_stream in on_message...
handle undefined or closed zmq_stream in on_message can happen if a message is waiting in a pipe and the web socket is closed before the message is handled. And give ZMQChannels a nice repr with their kernel ID

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widget_button.py
56 lines | 2.1 KiB | text/x-python | PythonLexer
"""ButtonWidget class.
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 DOMWidget, CallbackDispatcher
from IPython.utils.traitlets import Unicode, Bool
#-----------------------------------------------------------------------------
# Classes
#-----------------------------------------------------------------------------
class ButtonWidget(DOMWidget):
_view_name = Unicode('ButtonView', sync=True)
# Keys
description = Unicode('', help="Description of the button (label).", sync=True)
disabled = Bool(False, help="Enable or disable user changes.", sync=True)
def __init__(self, **kwargs):
"""Constructor"""
super(ButtonWidget, self).__init__(**kwargs)
self._click_handlers = CallbackDispatcher()
self.on_msg(self._handle_button_msg)
def on_click(self, callback, remove=False):
"""Register a callback to execute when the button is clicked.
The callback will be called with one argument,
the clicked button widget instance.
Parameters
----------
remove : bool (optional)
Set to true to remove the callback from the list of callbacks."""
self._click_handlers.register_callback(callback, remove=remove)
def _handle_button_msg(self, _, content):
"""Handle a msg from the front-end.
Parameters
----------
content: dict
Content of the msg."""
if content.get('event', '') == 'click':
self._click_handlers(self)