what does **kw mean?

zslevi@gmail.com levilista at gmail.com
Fri Jan 11 18:21:21 CET 2008


On Jan 11, 12:24 pm, Lie <Lie.1... at gmail.com> wrote:
> On Jan 11, 4:38 pm, "zsl... at gmail.com" <levili... at gmail.com> wrote:
>
> > I've been reading the following example, and couldn't figure out, what
> > **kw mean. (It's an empty dictionary, but what's the semantics):
>
> It's a keyword argument. It's some kind of repository for arguments
> that aren't recognized.
>
> If you have function like this:
> def func(a, *args, *kw):
>     print a
>     print args
>     print kw
>
> and you call the functin like this:
> func('value A', 'value B', 'value C', argumentA = 'value D', argumentB
> = 'value D')
> the extra arguments would normally raise an error, but with the * and
> **, Python would:
> - assign 'value B' and 'value C' to args
> - assign 'argumentA':'value D' and 'argumentB':'value E' to kw
>
> so if you run the function, it will output:
> ####
> value A
> ('value B', 'value C')
> {'argumentB': 'value E', 'argumentA': 'value D'}
> ####
>
> this args and kw can be accessed like a tuple and dictionary
> respectively
>
> See '4.7.2 Keyword Arguments' and '4.7.3 Arbitrary Argument Lists' on
> Python Help File

Thanks!



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