在python中用静态方法指针分配构造函数参数？

Question

使用下面的程序得到未定义的错误

class SignalHandler(object):  # pylint:  disable=too-few-public-methods
"""
Handles various user generated signals
"""

    def __init__(self,
             sigint_signalhandler=SignalHandler.signal_handler,
             sigquit_signalhandler=SignalHandler.signal_handler,
             sighup_signalhandler=SignalHandler.signal_handler):

        signal.signal(signal.SIGINT, sigint_signalhandler)
        signal.signal(signal.SIGQUIT, sigquit_signalhandler)
        signal.signal(signal.SIGHUP, sighup_signalhandler)

    @staticmethod
    def signal_handler(signalnum):
        print ('Ignoring signal : ', signalnum)

这就是错误的样子

import signalhandler
File "/usr/local/sandvine/scripts/upgrade-assistance/signalhandler.py", line 10, in <module>
class SignalHandler(object):  # pylint:  disable=too-few-public-methods
File "/usr/local/sandvine/scripts/upgrade-assistance/signalhandler.py", line 22, in SignalHandler
sigint_signalhandler=SignalHandler.signal_handler,
NameError: name 'SignalHandler' is not defined

所以最终我想传递一些自定义方法，如果没有，我将使用 SignalHandler 类提供的 signal_handler 方法。

Answer 1

将类上方的signal_handler 定义为普通方法，而不是在其内部作为静态方法。你不能在定义之前引用一个类，这就是你的__init__ 正在尝试做的事情。

或者，在 init 正文中使用 self.signal_handler 而不是 SignalHandler.signal_handler：

class Foo(object):
    def __init__(self, bar_printer=None):
        self.bar_printer = bar_printer if bar_printer else self._default_bar_printer

    @staticmethod
    def _default_bar_printer():
        print("bar")


f = Foo()
f.bar_printer()  # Prints "bar"

def better_bar_printer():
    print("The best bar!")

f2 = Foo(better_bar_printer)
f2.bar_printer()  # Prints "The best bar!"