mirror of
https://github.com/SickGear/SickGear.git
synced 2024-12-01 08:53:37 +00:00
131 lines
3.8 KiB
Python
131 lines
3.8 KiB
Python
# event/api.py
|
|
# Copyright (C) 2005-2014 the SQLAlchemy authors and contributors <see AUTHORS file>
|
|
#
|
|
# This module is part of SQLAlchemy and is released under
|
|
# the MIT License: http://www.opensource.org/licenses/mit-license.php
|
|
|
|
"""Public API functions for the event system.
|
|
|
|
"""
|
|
from __future__ import absolute_import
|
|
|
|
from .. import util, exc
|
|
from .base import _registrars
|
|
from .registry import _EventKey
|
|
|
|
CANCEL = util.symbol('CANCEL')
|
|
NO_RETVAL = util.symbol('NO_RETVAL')
|
|
|
|
|
|
def _event_key(target, identifier, fn):
|
|
for evt_cls in _registrars[identifier]:
|
|
tgt = evt_cls._accept_with(target)
|
|
if tgt is not None:
|
|
return _EventKey(target, identifier, fn, tgt)
|
|
else:
|
|
raise exc.InvalidRequestError("No such event '%s' for target '%s'" %
|
|
(identifier, target))
|
|
|
|
def listen(target, identifier, fn, *args, **kw):
|
|
"""Register a listener function for the given target.
|
|
|
|
e.g.::
|
|
|
|
from sqlalchemy import event
|
|
from sqlalchemy.schema import UniqueConstraint
|
|
|
|
def unique_constraint_name(const, table):
|
|
const.name = "uq_%s_%s" % (
|
|
table.name,
|
|
list(const.columns)[0].name
|
|
)
|
|
event.listen(
|
|
UniqueConstraint,
|
|
"after_parent_attach",
|
|
unique_constraint_name)
|
|
|
|
|
|
A given function can also be invoked for only the first invocation
|
|
of the event using the ``once`` argument::
|
|
|
|
def on_config():
|
|
do_config()
|
|
|
|
event.listen(Mapper, "before_configure", on_config, once=True)
|
|
|
|
.. versionadded:: 0.9.3 Added ``once=True`` to :func:`.event.listen`
|
|
and :func:`.event.listens_for`.
|
|
|
|
"""
|
|
|
|
_event_key(target, identifier, fn).listen(*args, **kw)
|
|
|
|
|
|
def listens_for(target, identifier, *args, **kw):
|
|
"""Decorate a function as a listener for the given target + identifier.
|
|
|
|
e.g.::
|
|
|
|
from sqlalchemy import event
|
|
from sqlalchemy.schema import UniqueConstraint
|
|
|
|
@event.listens_for(UniqueConstraint, "after_parent_attach")
|
|
def unique_constraint_name(const, table):
|
|
const.name = "uq_%s_%s" % (
|
|
table.name,
|
|
list(const.columns)[0].name
|
|
)
|
|
|
|
A given function can also be invoked for only the first invocation
|
|
of the event using the ``once`` argument::
|
|
|
|
@event.listens_for(Mapper, "before_configure", once=True)
|
|
def on_config():
|
|
do_config()
|
|
|
|
|
|
.. versionadded:: 0.9.3 Added ``once=True`` to :func:`.event.listen`
|
|
and :func:`.event.listens_for`.
|
|
|
|
"""
|
|
def decorate(fn):
|
|
listen(target, identifier, fn, *args, **kw)
|
|
return fn
|
|
return decorate
|
|
|
|
|
|
def remove(target, identifier, fn):
|
|
"""Remove an event listener.
|
|
|
|
The arguments here should match exactly those which were sent to
|
|
:func:`.listen`; all the event registration which proceeded as a result
|
|
of this call will be reverted by calling :func:`.remove` with the same
|
|
arguments.
|
|
|
|
e.g.::
|
|
|
|
# if a function was registered like this...
|
|
@event.listens_for(SomeMappedClass, "before_insert", propagate=True)
|
|
def my_listener_function(*arg):
|
|
pass
|
|
|
|
# ... it's removed like this
|
|
event.remove(SomeMappedClass, "before_insert", my_listener_function)
|
|
|
|
Above, the listener function associated with ``SomeMappedClass`` was also
|
|
propagated to subclasses of ``SomeMappedClass``; the :func:`.remove` function
|
|
will revert all of these operations.
|
|
|
|
.. versionadded:: 0.9.0
|
|
|
|
"""
|
|
_event_key(target, identifier, fn).remove()
|
|
|
|
def contains(target, identifier, fn):
|
|
"""Return True if the given target/ident/fn is set up to listen.
|
|
|
|
.. versionadded:: 0.9.0
|
|
|
|
"""
|
|
|
|
return _event_key(target, identifier, fn).contains()
|