Python classes losing attributes

Question

I have a peculiar python problem. During the course of execution of my gtk python application, some of my class objects mysteriously lose attributes, causing some of the fun

Answer 1

Well you can use property and inspect module to trace changes to attribute like this:

import sys
import inspect

def from_where_called():
    info = inspect.getframeinfo(sys._getframe(2))
    code = info.code_context[0] if info.code_context else ''
    return '%s:%s %s' % (info.filename, info.lineno, code)

def add_watched_attribute(name):  
    def attr_watch_get(self):
        value = getattr(self, '_' + name, 'unset')
        print from_where_called(), name, 'is', value
        return value

    def attr_watch_set(self, value):
        print from_where_called(), name, 'set to', value
        setattr(self, '_' + name, value)

    def attr_watch_delete(self):
        print from_where_called(), name, 'deleted'
        delattr(self,'_' + name)

    sys._getframe(1).f_locals[name] = property(
        attr_watch_get, attr_watch_set, attr_watch_delete
    )


class InspectedClass(object):
    add_watched_attribute('victim')

    def __init__(self):
        self.victim = 2

    def kill(self):
        del self.victim


x = InspectedClass()
x.victim = 'asdf'
x.kill()

Or you can use sys.settrace from this answer: https://stackoverflow.com/a/13404866/816449