Guido van Rossum wrote:
> But there were
> several suggestions that this would be fine functionality to add to
> the standard dict type -- and then I really don't see any other way to
> do this.
Given the constructor problem, and the issue with "this function expects a
plain dictionary", I think your original instinct to use a subclass may have
been correct.
The constructor is much cleaner that way:
# bag like behavior
dd = collections.autodict(int)
for elem in collection:
dd[elem] += 1
# setdefault-like behavior
dd = collections.autodict(list)
for page_number, page in enumerate(book):
for word in page.split():
dd[word].append(word)
And it can be a simple fact that for an autodict, "if key in d" and "d[key]"
may give different answers.
Much cleaner than making the semantics of normal dicts dependent on:
a. whether or not on_missing has been overridden
b. whether or not default_factory has been set
Cheers,
Nick.
--
Nick Coghlan | ncoghlan at gmail.com | Brisbane, Australia
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