Hi Martti,

On 11.10.2016 14:42, Martti Kühne wrote:
Hello list

I love the "new" unpacking generalisations as of pep448. And I found
myself using them rather regularly, both with lists and dict.
Today I somehow expected that [*foo for foo in bar] was equivalent to
itertools.chain(*[foo for foo in bar]), which it turned out to be a
The dict equivalent of the above might then be something along the
lines of {**v for v in dict_of_dicts.values()}. In case the values
(which be all dicts) are records with the same keys, one might go and
prepend the keys with their former keys using
         ("{}_{}".format(k, k_sub), v_sub)
         for k_sub, v_sub in v.items()
     ) for k, v in dict_of_dicts.items()
Was anyone able to follow me through this?

Reading PEP448 it seems to me that it's already been considered: https://www.python.org/dev/peps/pep-0448/#variations

The reason for not-inclusion were about concerns about acceptance because of "strong concerns about readability" but also received "mild support". I think your post strengthens the support given that you "expected it to just work". This shows at least to me that the concerns about readability/understandability are not justified much.

Personally, I find inclusion of */** expansion for comprehensions very natural. It would again strengthen the meaning of */** for unpacking which I am also in favor of.

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