assert hackable

I've got this real silly problem - assert is a reserved word in Python.

I can't define a function named assert because then I get a SyntaxError. At the moment I'm using _assert instead. It is ugly, and also, the _ is universally recognized as representing a private function or attribute so it's not a very good alternative.

I'll probably end up using assert_fact/retract_fact instead of assert/retract and that's fine. But, I just don't want to give up that easy. I did some experimenting and came up with this:

Kids! Don't try this at home! ;-)

This makes assert_hook catch ALL unhandled exceptions.

>>> import sys
>>> def assert_hook(t, val, tb):
...   if "exceptions.AssertionError" in repr(t):
...     ## call pyRete._assert(val)
...     print "I caught %s and now, I'm gonna assert it!" % (val)
...   else:
...     ## this is not an AssertionError, re-raise Exception
...     raise
>>> sys.excepthook = assert_hook

I just have to make sure that ALL Fact objects fail an Assertion

>>> class Fact(object):
...   def __nonzero__(self):
...     return False

Let's try it:

>>> foo = Fact()
>>> bar = { 'spam' : True, 'eggs' : False, }
>>> bar['spam']
True
>>> bar['foo']
Traceback (most recent call last):
...
KeyError: foo

Ok, so far, so good.

>>> assert foo
I caught <__main__.fact> and now, I'm gonna assert it!

Score! ;-)