[Python-Dev] Update on PEP 523 and adding a co_extra field to code objects (original) (raw)

Serhiy Storchaka storchaka at gmail.com
Tue Aug 30 14:55:16 EDT 2016

On 30.08.16 21:20, Antoine Pitrou wrote:

On Tue, 30 Aug 2016 18:12:01 +0000 Brett Cannon <brett at python.org> wrote:

Why not make it always a list? List objects are reasonably cheap in memory and access time... (unlike dicts)

Because I would prefer to avoid any form of unnecessary performance overhead for the common case. But the performance overhead of iterating over a 1-element list is small enough (it's just an array access after a pointer dereference) that it may not be larger than the overhead of the multiple tests and conditional branches your example shows.

Iterating over a tuple is even faster. It needs one pointer dereference less.

And for memory efficiency we can use just a raw array of pointers.

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