One of the marks of good software is that it understands how usersthink it works, and makes itself work that way. Two little bits ofhow Firefox works make a good illustration of this.

Start with Control-+, the keyboard shortcut for increasing thefont size. You may have hit this all the time, but let me askyou: do you type it with Shift? The top number row '+' is ashifted key; without shift, you have actually been typingControl-=. Firefox

Presented in the now-traditional illustrated form:

; sdig ns gcluk.netns1.gcluk.net.ns2.gcluk.net.; dig mx web1.gcluk.net @ns1.gcluk.net[...];; ANSWER SECTION:web1.gcluk.net. IN A 65.98.36.90;; AUTHORITY SECTION:web1.gcluk.net. IN NS .

(TTLs have been omitted for clarity.)

That

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,