[Python-Dev] Directions for reproducing the coredump (original) (raw)

Ka-Ping Yee ping@lfw.org
Sat, 12 Aug 2000 01:09:53 -0700 (PDT)

On Fri, 11 Aug 2000, Ka-Ping Yee wrote:

On Fri, 11 Aug 2000, Ka-Ping Yee wrote: > I have successfully reproduced the core dump.

I'm investigating. Top of the stack looks like:

This chunk of stack repeats lots and lots of times. The problem is due to infinite recursion in your repr routine:

class Requirement:
    "A requirement, together with a message to be shown if it's violated."
    def __init__(self, wff, message=None):
        self.predicate = wff
        self.message = message

    def str(self):
        return display_expression(self.predicate)

    def __repr__(self):
        if self.message:
            return self.message
        else:
            return str(self)

Notice that Requirement.repr calls str(self), which triggers Requirement.repr again because there is no str method.

If i change "def str(self)" to "def str(self)", the problem goes away and everything works properly.

With a reasonable stack depth limit in place, this would produce a run-time error rather than a segmentation fault.

-- ?!ng

"This code is better than any code that doesn't work has any right to be." -- Roger Gregory, on Xanadu