[Python-Dev] defaultdict and on_missing() (original) (raw)

Edward C. Jones edcjones at comcast.net
Wed Feb 22 21:27:56 CET 2006

Guido van Rossen wrote:

I think the pattern hasn't been commonly known; people have been struggling with setdefault() all these years.

I use setdefault only to speed up the following code pattern:

if akey not in somedict: somedict[akey] = list() somedict[akey].append(avalue)

These lines of simple Python are much easier to read and write than

somedict.setdefault(akey, list()).append(avalue)