[Python-ideas] Allow using ** twice

[Markus Unterwaditzer]

Actually i wouldn't expect += to be the same as dict.update, but it rather would create a new dictionary.

-- Markus (from phone)

Andrew Barnert <abarnert at yahoo.com> wrote:
>On Jun 6, 2013, at 8:43, Haoyi Li <haoyi.sg at gmail.com> wrote:
>
>> > There should be one way to do it...
>> 
>> I'd agree except, well, there are two different things that people
>want to do here!
>
>Actually, there's three:
>
>1. Right values take precedence.
>2. Left values take precedence.
>3. Assert that there are no duplicate keys.
>
>I think the first is what people would expect, and want, more often,
>because it's exactly what you get when you do the obvious thing today.
>It also means a+=b means a.update(b), just as it means a.extend(b) for
>sequences--and note that there is no method that adds the new keys from
>b while leaving existing ones alone or raising an exception.
>
>But I also think that most of the time people won't care. If you write
>draw(x, y, **(image_keywords * window_keywords)), you've got two non
>overlapping sets of keys.
>
>> So in the end you're gonna have to let people do both, somehow.
>
>Or you can provide one obvious way to do the common case that people
>will use all the time, and explain how you do the less obvious cases
>when they occasionally come up.
>
>Also, note that if we implement case 1, it's pretty obvious how to do
>case 2: just do b+a instead of a+b.