Pre-PEP: Dictionary accumulator methods

[Brian van den Broek]

Raymond Hettinger said unto the world upon 2005-03-18 20:24:
> I would like to get everyone's thoughts on two new dictionary methods:
> 
>         def count(self, value, qty=1):
>             try:
>                 self[key] += qty
>             except KeyError:
>                 self[key] = qty
> 
>         def appendlist(self, key, *values):
>             try:
>                 self[key].extend(values)
>             except KeyError:
>                 self[key] = list(values)
> 
> The rationale is to replace the awkward and slow existing idioms 
> for dictionary based accumulation:
> 
>     d[key] = d.get(key, 0) + qty
>     d.setdefault(key, []).extend(values)

<SNIP>


Hi all,

I am *far* less experienced with Python and programming than those 
who've weighed in as yet.

I quite like count, though I agree with posts up thread that `count' 
might not be the best name.

For appendlist, I would have expected

def appendlist(self, key, sequence):
     try:
         self[key].extend(sequence)
     except KeyError:
         self[key] = list(sequence)


I am, however, very open to the possibility that this says more about 
my level of experience than it does about which way is best :-)

Best to all,

Brian vdB