21.11.17 11:27, Kirill Balunov пише:
    Your implementation iterates seq multiple times. But iterable
    unpacking syntax works with an arbitrary iterable, and iterates it
    only once.


Oh sorry, I know that my implementation iterates seq multiple times, I only provide this to show the idea. It can be much optimized at C level. I just want to understand if it's worth the time and effort.

You can implement the first case, but for other cases you will need a storage for saving intermediate items. And using a list is a good option.

    And you already have mentioned a question about mutable sequence.

    If these conditions and restrictions suit you, you can use your
    good_star_exp() in your code or share it with others. But the
    semantic of iterable unpacking can't be changed.


And how do you look at something like this (deferred star evaluation)?:

a, ?*b, c, d = something_iterable

This will be not different from

a, *b, c, d = something_iterable
b = iter(b)

There is nothing deferred here.

The only possible benefit can be in the case

a, b, ?*c = something_iterable

But I have doubts that this special case deserves introducing a new syntax.

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