Martin v. Löwis <mar...@v.loewis.de> added the comment:
> The missing key reports the default object, but doesn't set that key
> or value object in the dict.
That's just not true. Re-read the line in the doc string where it
puts the default value into the dict, under the key being accessed.
> For example, to represent a graph structure, it is helpful to use a
> dict-of-dicts.
No problem:
py> from collections import defaultdict
py> weights=defaultdict(dict)
py> weights['a']['b']=17
py> weights['a']['c']=5
py> weights['a']
{'c': 5, 'b': 17}
See? It remembered the default value, and the value for the 'a'
key got changed and can now be modified. The whole point of defaultdict
was to replace setdefault, so that setdefault can eventually be
eliminated, see
http://mail.python.org/pipermail/python-dev/2006-February/061169.html
http://mail.python.org/pipermail/python-dev/2006-February/061261.html
Apparently, the plan for removing setdefault is now forgotten. Perhaps
this would be a good time to revive it, with a proper deprecation
procedure. If it is to be removed, I'm -1 for "fixing" anything about
it.
----------
_______________________________________
Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue5730>
_______________________________________
_______________________________________________
Python-bugs-list mailing list
Unsubscribe:
http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
