Hi Guido,

On 22/01/2021 5:20 am, Guido van Rossum wrote:

On Wed, Jan 20, 2021 at 9:16 AM Mark Shannon <mark@hotpy.org mailto:mark@hotpy.org> wrote:

I've updated the PEP in light of my experiments and feedback.
The new API is simpler and a bit more backwards compatible.

https://www.python.org/dev/peps/pep-0651
<https://www.python.org/dev/peps/pep-0651/>

Minor question: what's the `where` argument to `Py_CheckStackDepth()` for?

The same as for Py_EnterRecursiveCall(where); it gets incorporated into the exception message.

The implementation section doesn't mention how you intend to avoid the C stack for Python-to-Python calls. I have some idea, but it would be nice if you explained this a bit more. (I'm guessing you are planning to move some state from local variables into the frame object, store a "return location" (really frame object + bytecode program counter) somewhere, and then jump to the top of `_PyEval_EvalFrameDefault()`, or at least somewhere near the top. Of course this requires adjusting the various `CALL_*` opcodes to check whether the target is a Python function or not. On `RETURN_VALUE` you reverse the process, but only if the call came from the previous mechanism. Do I get a lollipop? :-)

Yes you do. 🍭

I'll expand the PEP a bit to include that information.

I'm guessing you needn't do anything for generators -- IIRC recursion through `next()` is not possible, since an active generator cannot be entered recursively.

Yes. It might be nice to handle generators as well, but it is not necessary.

Cheers, Mark.

-- --Guido van Rossum (python.org/~guido http://python.org/~guido) /Pronouns: he/him //(why is my pronoun here?)/ http://feministing.com/2015/02/03/how-using-they-as-a-singular-pronoun-can-change-the-world/