[Python-ideas] Dict joining using + and +=

[Guido van Rossum]

On Wed, Feb 27, 2019 at 8:50 AM Rhodri James <rhodri at kynesim.co.uk> wrote:

> On 27/02/2019 16:25, João Matos wrote:
> > I would like to propose that instead of using this (applies to Py3.5 and
> upwards)
> > dict_a = {**dict_a, **dict_b}
> >
> > we could use
> > dict_a = dict_a + dict_b
> >
> > or even better
> > dict_a += dict_b
>
> While I don't object to the idea of concatenating dictionaries, I feel
> obliged to point out that this last is currently spelled
> dict_a.update(dict_b)
>

This is likely to be controversial. But I like the idea. After all, we have
`list.extend(x)` ~~ `list += x`. The key conundrum that needs to be solved
is what to do for `d1 + d2` when there are overlapping keys. I propose to
make d2 win in this case, which is what happens in `d1.update(d2)` anyways.
If you want it the other way, simply write `d2 + d1`.

-- 
--Guido van Rossum (python.org/~guido)
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