[Python-Dev] Accepting PEP 590 (Vectorcall)

Petr Viktorin encukou at gmail.com
Tue May 28 07:52:53 EDT 2019

As BDFL-Delegate, I am accepting PEP 590 -- Vectorcall: a fast calling 
protocol for CPython.

There was a major last-minute change to the text (though one that was 
discussed since PyCon US): The API is not finalized yet, and it's 
provided using private names (with leading underscores). We intend to 
use the Python 3.8 cycle to get feedback from consumers, and finalize it 
in 3.9.

Thanks to Jeroen Demeyer, who spent a lot of time pushing this forward, 
and probably has some new gray hair from interactions with me and other 
core devs. Without his PEP 580 (and its implementation), the simpler PEP 
590 would not be possible.
It might not be apparent if some of his interactions are taken out of 
context, but throughout the process Jeroen always worked to make Python 
better, and he acted professionally even as we made decisions he didn't 
agree with.

Thanks to Mark Shannon for providing major insights, patiently 
explaining that they actually are good ideas, and for the initial 

Thanks to Stefan Behnel, Nick Coghlan, Victor Stinner and everyone else 
involved in PEPs 576, 579, 580 and 590.

I learned a lot in this process.

This is my first time as BDFL-delegate. If you have any criticism of the 
way I handled things, please share! (Assume I have tough skin, but keep 
to the code of conduct.) I'd be happy to know how I can improve.

And now, I'm off to get the implementation reviewed!

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