twisted的installReactor()函数

#twisted的安装反应堆函数
def installReactor(reactor):
    """
    Install reactor C{reactor}.

    @param reactor: An object that provides one or more IReactor* interfaces.
    """
    # this stuff should be common to all reactors.
    import twisted.internet#导入包，会在sys.modules添加一个module
    import sys
    if 'twisted.internet.reactor' in sys.modules:
        raise error.ReactorAlreadyInstalledError("reactor already installed")
    twisted.internet.reactor = reactor#为twisted.internet模块添加一个属性
    sys.modules['twisted.internet.reactor'] = reactor#手动添加一个模块

>>> import twisted.internet
>>> print type(twisted.internet)
<type 'module'>
>>> twisted.internet.__name__
'twisted.internet'
>>> twisted.internet.reactor = 'ok'
>>> twisted.internet.reactor
'ok'

reactor的选择，不同平台会选择不同的reactor，比如linux会选epollreactor，从internet导入reactor.py时，执行下面代码

from __future__ import division, absolute_import

import sys
del sys.modules['twisted.internet.reactor']
from twisted.internet import default
default.install()

#default.py模块返回安装函数
def _getInstallFunction(platform):

    try:
        if platform.isLinux():
            try:
                from twisted.internet.epollreactor import install
            except ImportError:
                from twisted.internet.pollreactor import install
        elif platform.getType() == 'posix' and not platform.isMacOSX():
            from twisted.internet.pollreactor import install
        else:
            from twisted.internet.selectreactor import install
    except ImportError:
        from twisted.internet.selectreactor import install
    return install

install = _getInstallFunction(platform)

调用default.install()时就安装了reactor