On 04/11/2011 05:44 PM, Chris Angelico wrote:
On Tue, Apr 12, 2011 at 8:41 AM, MRAB<pyt...@mrabarnett.plus.com> wrote:
I'm not sure that "setdefault" should take **kw args for this because
of its existing argument structure (key + optional value).
A new method like "updatedefault" may be better, IMHO. It would act
like "update" except that it wouldn't overwrite existing values.
Wouldn't x.updatedefault(y) be pretty much y.update(x) ?
As I understand, the difference would be the following pseudocode:
def update(self, d):
for k,v in dict(d).iteritems():
self[k] = v
def updatedefault(self, d={}, **kwargs):
for k,v in chain(
dict(d).iteritems(),
kwargs.iteritems()
):
# MRAB's comment about "wouldn't overwrite existing"
if k not in self:
self[k] = v
My concern with the initial request is that dict.setdefault()
already returns the (existent or defaulted) value, so you can do
things like
d.setdefault(my_key, []).append(item)
If you allow it to take multiple kwargs, what would the return
value be (positionality of kwargs is lost, so returning a tuple
wouldn't be readily possible)?
Finally, if it were added, I'd call it something like merge()
-tkc
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