16.10.21 17:07, Erik Demaine пише:
> Extended unpacking notation (* and **) from PEP 448 gives us great ways
> to concatenate a few iterables or dicts:
>
> ```
> (*it1, *it2, *it3) # tuple with the concatenation of three iterables
> [*it1, *it2, *it3] # list with the concatenation of three iterables
> {*it1, *it2, *it3} # set with the union of three iterables
> {**dict1, **dict2, **dict3} # dict with the combination of three dicts
> # roughly equivalent to dict1 | dict2 | dict3 thanks to PEP 584
> ```
>
> I propose (not for the first time) that similarly concatenating an
> unknown number of iterables or dicts should be possible via comprehensions:
>
> ```
> (*it for it in its) # tuple with the concatenation of iterables in 'its'
> [*it for it in its] # list with the concatenation of iterables in 'its'
> {*it for it in its} # set with the union of iterables in 'its'
> {**d for d in dicts} # dict with the combination of dicts in 'dicts'
> ```
It was considered and rejected in PEP 448. What was changed since? What
new facts or arguments have emerged?
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