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Add PyFrame_SetLineNumber() for Cython #118720
Description
Feature or enhancement
Proposal:
CPython hides PyFrameObject internals so Cython include pycore_frame.h to set f_lineno.
Let's provide PyFrame_SetLineNumber() for Cython.
Has this already been discussed elsewhere?
This is a minor feature, which does not need previous discussion elsewhere
Activity
Ben4C commentedon Aug 14, 2024
Hello, I've been working on this for a little while, but I'm a bit lost on implementing the changes.
From what I understand think I'm supposed to create a public API to set the
f_filenovariable so I usedPyAPI_FUNC(int) PyFrame_SetLineNumber(PyFrameObject *f, int lineno)inInclude/cpython/frameobject.hwhich usesframe_setlinenofromframeobject.cto change thef_lineno. I've been trying to get a test to pass to verify that this works inLib/test/test_frame.pybut I'm not sure if my approach or logic is correct.This is what I have so far: Ben4C@1e82093
pythongh-118720: Add PyFrame_SetLineNumber() function
pythongh-118720: Add PyFrame_SetLineNumber() function
pythongh-118720: Add PyFrame_SetLineNumber() function
vstinner commentedon Mar 14, 2025
This function was also discussed at #130931.
vstinner commentedon Mar 14, 2025
I wrote PR gh-131246 to add
PyFrame_SetLineNumber().markshannon commentedon Mar 17, 2025
I think is going to be very confusing if
PyFrame_SetLineNumberhas different behavior from setting the line number in Pythonframe.f_lineno = ....The
f_linenofield in the the frame object is a cache for the computed line number.It may overwritten by the interpreter, so setting it will not work reliably.
vstinner commentedon Mar 17, 2025
I wrote this function to replace the Cython macro:
#define __Pyx_PyFrame_SetLineNumber(frame, lineno) (frame)->f_lineno = (lineno)I suppose that Cython sets
f_linenoto produce a traceback with specific line number.cc @scoder @da-woods
da-woods commentedon Mar 17, 2025
Yes - it's used directly after creating a frame for that purpose.
(It's also used in the old, pre-sys-monitoring code. I would not worry about replacing that usage because I think that's only on older Python versions)
markshannon commentedon Mar 18, 2025
So what are the proposed semantics of
PyFrame_SetLineNumber(), how do we test it?