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"""Base class to manage widgets"""
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#-----------------------------------------------------------------------------
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# Copyright (C) 2013 The IPython Development Team
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#
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# Distributed under the terms of the BSD License. The full license is in
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# the file COPYING, distributed as part of this software.
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#-----------------------------------------------------------------------------
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#-----------------------------------------------------------------------------
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# Imports
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#-----------------------------------------------------------------------------
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from weakref import ref
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from IPython.config import LoggingConfigurable
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from IPython.core.prompts import LazyEvaluate
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from IPython.core.getipython import get_ipython
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from IPython.utils.traitlets import Instance, Unicode, Dict, Any
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#-----------------------------------------------------------------------------
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# Code
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#-----------------------------------------------------------------------------
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def lazy_keys(dikt):
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"""Return lazy-evaluated string representation of a dictionary's keys
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Key list is only constructed if it will actually be used.
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Used for debug-logging.
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"""
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return LazyEvaluate(lambda d: list(d.keys()))
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class WidgetManager(LoggingConfigurable):
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"""Manager for Widgets in the Kernel"""
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shell = Instance('IPython.core.interactiveshell.InteractiveShellABC')
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def _shell_default(self):
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return get_ipython()
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iopub_socket = Any()
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def _iopub_socket_default(self):
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return self.shell.parent.iopub_socket
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session = Instance('IPython.kernel.zmq.session.Session')
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def _session_default(self):
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if self.shell is None:
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return
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return self.shell.parent.session
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widgets = Dict()
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# Public APIs
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def register_widget(self, widget):
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"""Register a new widget"""
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self.widgets[widget.widget_id] = ref(widget)
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widget.shell = self.shell
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widget.iopub_socket = self.iopub_socket
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widget.create()
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return widget.widget_id
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def unregister_widget(self, widget_id):
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"""Unregister a widget, and destroy its counterpart"""
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# unlike get_widget, this should raise a KeyError
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widget_ref = self.widgets.pop(widget_id)
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widget = widget_ref()
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if widget is None:
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# already destroyed, nothing to do
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return
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widget.destroy()
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def get_widget(self, widget_id):
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"""Get a widget with a particular id
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Returns the widget if found, otherwise None.
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This will not raise an error,
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it will log messages if the widget cannot be found.
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"""
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if widget_id not in self.widgets:
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self.log.error("No such widget: %s", widget_id)
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self.log.debug("Current widgets: %s", lazy_keys(self.widgets))
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return
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# call, because we store weakrefs
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widget = self.widgets[widget_id]()
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if widget is None:
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self.log.error("Widget %s has been removed", widget_id)
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del self.widgets[widget_id]
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self.log.debug("Current widgets: %s", lazy_keys(self.widgets))
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return
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return widget
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# Message handlers
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def widget_update(self, stream, ident, msg):
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"""Handler for widget_update messages"""
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content = msg['content']
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widget_id = content['widget_id']
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widget = self.get_widget(widget_id)
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if widget is None:
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# no such widget
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return
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widget.handle_update(content['data'])
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def widget_destroy(self, stream, ident, msg):
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"""Handler for widget_destroy messages"""
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content = msg['content']
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widget_id = content['widget_id']
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widget = self.get_widget(widget_id)
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if widget is None:
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# no such widget
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return
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widget.handle_destroy(content['data'])
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del self.widgets[widget_id]
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__all__ = ['WidgetManager']
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