[Python-Dev] On the METH_FASTCALL calling convention (original) (raw)

Victor Stinner vstinner at redhat.com
Tue Jul 10 19:20:12 EDT 2018

2018-07-07 10:55 GMT+02:00 Serhiy Storchaka <storchaka at gmail.com>:

There is my idea. Split every of keyword argument parsing functions on two parts. The first part linearize keyword arguments, it converts positional and keyword arguments (in whatever form they were presented) into a linear array of PyObject* (with NULLs for not specified optional arguments). The second part is common and similar to PyArgParseStack(), but supports NULLs. It converts an array of PyObject* to a sequence of C values. I tried to implement this idea, is is not simple, and results were mixed, but I don't loss a hope.

And here we return to METHFASTCALL|METHKEYWORDS. The first part of handling arguments can be made outside of the C function, by the calling API. Then the signature of the C function can be simpler, the same as for METHFASTCALL. But we need to expose the list of keyword parameter names as an attribute of CFunction. I don't know whether this ides is vital or dead, but I' going to try it. And implementing it will change the METHFASTCALL|METHKEYWORDS calling convention a lot.

I don't understand why changing the implementation of PyArg_Parse*() would require to require the FASTCALL calling convention?

Victor

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