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To: python-list@python.org
From: Peter Otten <__peter__@web.de>
Subject: Re: Suggestion: PEP for popping slices from lists
Date: Thu, 08 Aug 2013 12:07:16 +0200
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Neatu Ovidiu Gabriel wrote:

> The list.pop(index) returns the element represented by the index and also
> reduces the list by removing that element. So it a short one liner for
> doing both things. But when it comes for popping a slice of the list there
> is nothing similar for doing in that simple way.
> 
> If you want to remove a slice and also reduce the list you will have
> something like this:
> 
> a_list, a_slice = a_list[:size], a_list[size:]
> 
> or even worser if you try to do the same for something in the middle.
> 
> My proposal is the extension of list.pop for accepting a way for popping
> slices.
> 
> When doing this:
> 
> a_list.pop(i,j)
> 
> pop will return the slice [i,j] and remove it from the list.
> 
> For popping from an index to the end:
> 
> a_list.pop(i, len(a_list))
> 
> Or even emptying the whole list:
> 
> a_list.pop(0, len(a_list))
> 
> 
> So this is it :)

You'd use 'del' to remove a slice from a list. So:

>>> def pop_slice(items, *indices):
...     x = slice(*indices)
...     result = items[x]
...     del items[x]
...     return result
... 
>>> items = range(10)
>>> pop_slice(items, 3)
[0, 1, 2]
>>> items
[3, 4, 5, 6, 7, 8, 9]
>>> pop_slice(items, 3, 4)
[6]
>>> items
[3, 4, 5, 7, 8, 9]
>>> pop_slice(items, None, None, 2)
[3, 5, 8]
>>> items
[4, 7, 9]

But what's your use case?
Does it occur often enough that you cannot afford a two-liner like

result = items[start:stop]
del items[start:stop]

?