Nick Coghlan wrote:
1. Applies only if you are making large slices, or a lot of slices with each containing at least 3 elements.
A view can also *cost* memory, when it looks at a small piece of a large item. The view will keep the entire item alive, even though it needs only a small piece.
That is correct.
2. Hell no. The *elements* aren't copied, pointers to the elements are. If you *don't* copy the pointers, then every item access through the view involves an indirection as the index into the original sequence gets calculated.
If you have
x=(1,2,...100001) y=x[:-1]
then you copy 100000 pointers AND you INCREF them AND you DECREF them when y dies.
The unfortunate case by (1) would be:
x=(1,2,...100001) x=x[:1]
So views *may* save memory in some applications, but are unlikely to save time in any application (except any saving resulting from the memory saving).
They do. If tp_dealloc of a tuple view doesn't decref the pointers.
We should look for what is the most common case.
Gerald
-PS: the PEP for the removal ought to have a ":)" at the end.
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