signals.py 文件源码

def __init__(self, default_handler):
        self.called = False
        self.original_handler = default_handler
        if isinstance(default_handler, int):
            if default_handler == signal.SIG_DFL:
                # Pretend it's signal.default_int_handler instead.
                default_handler = signal.default_int_handler
            elif default_handler == signal.SIG_IGN:
                # Not quite the same thing as SIG_IGN, but the closest we
                # can make it: do nothing.
                def default_handler(unused_signum, unused_frame):
                    pass
            else:
                raise TypeError("expected SIGINT signal handler to be "
                                "signal.SIG_IGN, signal.SIG_DFL, or a "
                                "callable object")
        self.default_handler = default_handler