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# -*- test-case-name: twisted.test.test_application -*- # Copyright (c) 2006-2007 Twisted Matrix Laboratories. # See LICENSE for details.
""" Plugin-based system for enumerating available reactors and installing one of them. """
from zope.interface import Interface, Attribute, implements
from twisted.plugin import IPlugin, getPlugins from twisted.python.reflect import namedAny
class IReactorInstaller(Interface): """ Definition of a reactor which can probably be installed. """ shortName = Attribute(""" A brief string giving the user-facing name of this reactor. """)
description = Attribute(""" A longer string giving a user-facing description of this reactor. """)
def install(): """ Install this reactor. """
# TODO - A method which provides a best-guess as to whether this reactor # can actually be used in the execution environment.
class NoSuchReactor(KeyError): """ Raised when an attempt is made to install a reactor which cannot be found. """
class Reactor(object): """ @ivar moduleName: The fully-qualified Python name of the module of which the install callable is an attribute. """ implements(IPlugin, IReactorInstaller)
def __init__(self, shortName, moduleName, description): self.shortName = shortName self.moduleName = moduleName self.description = description
def install(self): namedAny(self.moduleName).install()
def getReactorTypes(): """ Return an iterator of L{IReactorInstaller} plugins. """ return getPlugins(IReactorInstaller)
def installReactor(shortName): """ Install the reactor with the given C{shortName} attribute.
@raise NoSuchReactor: If no reactor is found with a matching C{shortName}.
@raise: anything that the specified reactor can raise when installed. """ for installer in getReactorTypes(): if installer.shortName == shortName: return installer.install() raise NoSuchReactor(shortName)
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