Question

Simple question; How do you read the return value of a function that is called as a signal handler?

import signal

def SigHand(sig, frm):
    return 'SomeValue'

signal.signal(signal.SIGCHLD, SigHand)
signal.pause()

Is there a way to read the return value 'SomeValue' other than setting it as a global?

Answer 1

You could create a simple class with a return value attribute.

>>> import signal
>>> class SignalHandler(object):
...     def __init__(self):
...         self.retval = None
...     def handle(self, sig, frm):
...         self.retval = sig
... 
>>> s = SignalHandler()
>>> s.retval
>>> signal.signal(signal.SIGALRM, s.handle)
0
>>> signal.alarm(1)
0
>>> s.retval
14