# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.

"""
Backwards-compatibility plugin for the Qt reactor.

This provides a Qt reactor plugin named C{qt} which emits a deprecation
warning and a pointer to the separately distributed Qt reactor plugins.
"""

import warnings

from twisted.application.reactors import Reactor, NoSuchReactor

wikiURL = 'http://twistedmatrix.com/trac/wiki/QTReactor'
errorMessage = ('qtreactor is no longer a part of Twisted due to licensing '
'issues. Please see %s for details.' % (wikiURL,))

class QTStub(Reactor):
"""
Reactor plugin which emits a deprecation warning on the successful
installation of its reactor or a pointer to further information if an
ImportError occurs while attempting to install it.
"""
def __init__(self):
super(QTStub, self).__init__(
'qt', 'qtreactor', 'QT integration reactor')


def install(self):
"""
Install the Qt reactor with a deprecation warning or try to point
the user to further information if it cannot be installed.
"""
try:
super(QTStub, self).install()
except (ValueError, ImportError):
raise NoSuchReactor(errorMessage)
else:
warnings.warn(
"Please use -r qt3 to import qtreactor",
category=DeprecationWarning)


qt = QTStub()