/usr/lib/python2.7/dist-packages/IPython/core/events.py is in python-ipython 5.1.0-3.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 | """Infrastructure for registering and firing callbacks on application events.
Unlike :mod:`IPython.core.hooks`, which lets end users set single functions to
be called at specific times, or a collection of alternative methods to try,
callbacks are designed to be used by extension authors. A number of callbacks
can be registered for the same event without needing to be aware of one another.
The functions defined in this module are no-ops indicating the names of available
events and the arguments which will be passed to them.
.. note::
This API is experimental in IPython 2.0, and may be revised in future versions.
"""
from __future__ import print_function
class EventManager(object):
"""Manage a collection of events and a sequence of callbacks for each.
This is attached to :class:`~IPython.core.interactiveshell.InteractiveShell`
instances as an ``events`` attribute.
.. note::
This API is experimental in IPython 2.0, and may be revised in future versions.
"""
def __init__(self, shell, available_events):
"""Initialise the :class:`CallbackManager`.
Parameters
----------
shell
The :class:`~IPython.core.interactiveshell.InteractiveShell` instance
available_callbacks
An iterable of names for callback events.
"""
self.shell = shell
self.callbacks = {n:[] for n in available_events}
def register(self, event, function):
"""Register a new event callback
Parameters
----------
event : str
The event for which to register this callback.
function : callable
A function to be called on the given event. It should take the same
parameters as the appropriate callback prototype.
Raises
------
TypeError
If ``function`` is not callable.
KeyError
If ``event`` is not one of the known events.
"""
if not callable(function):
raise TypeError('Need a callable, got %r' % function)
self.callbacks[event].append(function)
def unregister(self, event, function):
"""Remove a callback from the given event."""
self.callbacks[event].remove(function)
def trigger(self, event, *args, **kwargs):
"""Call callbacks for ``event``.
Any additional arguments are passed to all callbacks registered for this
event. Exceptions raised by callbacks are caught, and a message printed.
"""
for func in self.callbacks[event][:]:
try:
func(*args, **kwargs)
except Exception:
print("Error in callback {} (for {}):".format(func, event))
self.shell.showtraceback()
# event_name -> prototype mapping
available_events = {}
def _define_event(callback_proto):
available_events[callback_proto.__name__] = callback_proto
return callback_proto
# ------------------------------------------------------------------------------
# Callback prototypes
#
# No-op functions which describe the names of available events and the
# signatures of callbacks for those events.
# ------------------------------------------------------------------------------
@_define_event
def pre_execute():
"""Fires before code is executed in response to user/frontend action.
This includes comm and widget messages and silent execution, as well as user
code cells."""
pass
@_define_event
def pre_run_cell():
"""Fires before user-entered code runs."""
pass
@_define_event
def post_execute():
"""Fires after code is executed in response to user/frontend action.
This includes comm and widget messages and silent execution, as well as user
code cells."""
pass
@_define_event
def post_run_cell():
"""Fires after user-entered code runs."""
pass
@_define_event
def shell_initialized(ip):
"""Fires after initialisation of :class:`~IPython.core.interactiveshell.InteractiveShell`.
This is before extensions and startup scripts are loaded, so it can only be
set by subclassing.
Parameters
----------
ip : :class:`~IPython.core.interactiveshell.InteractiveShell`
The newly initialised shell.
"""
pass
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