Order of object cleanup at interpreter exit?

Rob W. W. Hooft rob at hooft.net
Mon Feb 14 10:35:58 CET 2000

I am writing a package (98% python) that controls an analytical robot.
The robot is controlled via a simple text protocol over a socket

When the robot control object is garbage-collected, the __del__ method
takes care of a proper termination of the socket connection by sending
a last "EXIT" command:

def sendfixed(sock,data):
    while l<len(data):

class Robot:
    def __del__(self):
	if self.status>0:

I have noticed that this does not work if the __del__ method is called
when the interpreter is exiting (i.e., when I am using a Robot() object
in the __main__ module at the global scope). I get:

Exception exceptions.TypeError: 'call of non-function (type None)' in 
 <method Robot.__del__ of Robot instance at 81c8778> ignored

And indeed, it seems that the "sendfixed" function was already garbage
collected: "print sendfixed" just before the call reports "None"....

I was not aware that it was "illegal" to call a function from a destructor.
Is this a strange caveat? Bug? Feature? Any way to avoid it?
Rob Hooft
=====   rob at hooft.net          http://www.xs4all.nl/~hooft/rob/  =====
=====   R&D, Nonius BV, Delft  http://www.nonius.nl/             =====
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