[Python-Dev] Proposal: defaultdict

[Gareth McCaughan]

> >>   d.get(key, [], True).append(value)
> > 
> > hmm.  are you sure you didn't just reinvent setdefault ?
> 
> I'm reasonably sure I copied it on purpose, only with a name that isn't 100% 
> misleading as to what it does ;)

Heh. From the original Usenet posting that suggested the capability
that was added in the form of "setdefault":

  | I suggest a minor change: another optional argument to
  | "get" so that
  | 
  |     dict.get(item,default,flag)
  | 
  | is equivalent to
  | 
  |     if dict.has_key(item):
  |       VALUE IS dict[item]
  |     else:
  |       if flag: dict[item] = default    <-- This is all that's new
  |       VALUE IS default
  | 
  | but presumably more efficient.

The response was a chorus of people saying "Not a bad idea, but
that flag sucks. It needs a separate method." :-)

-- 
g