[Python-Dev] Tweak to PEP 523 for storing a tuple in co_extra (original) (raw)

Yury Selivanov yselivanov.ml at gmail.com
Sat Sep 3 18:03:17 EDT 2016

On 2016-09-03 12:27 PM, Brett Cannon wrote:

Below is the coextra section of PEP 523 with the update saying that users are expected to put a tuple in the field for easier simultaneous use of the field.

Since the coextra discussions do not affect CPython itself I'm planning on landing the changes stemming from the PEP probably on Monday.

Tuples are immutable. If you have multiple co_extra users then they will have to either mutate tuple (which isn't always possible, for instance, you can't increase size), or to replace it with another tuple.

Creating lists is a bit more expensive, but item access speed should be in the same ballpark.

Another question -- sorry if this was discussed before -- why do we want a PyObject* there at all? I.e. why don't we create a dedicated struct CoExtraContainer to manage the stuff in co_extra? My understanding is that the users of co_extra are C-level python optimizers and profilers, which don't need the overhead of CPython API.

This way my work to add an extra caching layer (which I'm very much willing to continue to work on) wouldn't require another set of extra fields for code objects.

Yury

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