The problem with LiveJournal is that youcan't stop partway through reading your friendslist; unless you have abetter memory than me, once you start reading it you need to read allthe way back to where you last stopped. The result is somewhat likeSpace Invaders; a stream of entries comes at you and you have to readthem all or die. In turn, this makes reading LiveJournal friendslistsnot a casual activity; if I can't commit enough time to read all of thenew entries that have

This is the kind of hack where I present the Python code first andexplain it later:

def memo1(func):  def _wrap(self):    r = func(self)    setattr(self, func.func_name, \            lambda : r)    return r  return _wrapclass Foo(object):  ...  def invar(self):    return complex(self.field1) or \           complex2(self.field2)  invar = memo1(invar)

Here,