[shihai1991]

https://bugs.python.org/issue43009

• Issue: Port curses capi pointer array to a struct #87175

[vstinner]

Hum, this change is backward incompatible. I don't know how to proceed. Is this API used outside Python, in 3rd party projects?

@encukou @serhiy-storchaka @methane: Is this change reasonable?

Note: I asked @shihai1991 to write this change ;-)

[methane]

The only user I found is this.
https://foss.heptapod.net/pypy/cffi/-/blob/cea8f1260587a4cf6ad230a00148cabea0f61572/demo/_curses.py#L972

[vstinner]

https://foss.heptapod.net/pypy/cffi/-/blob/cea8f1260587a4cf6ad230a00148cabea0f61572/demo/_curses.py#L972

It's a demo and it's commented, so it seems ok.

Moreover, the demo uses PyCursesInitialised; which is not affected by this change.

[vstinner]

Please document the incompatible change with a NEWS entry (blurb) and document in C API > Porting to Python 3.10 of:
https://docs.python.org/dev/whatsnew/3.10.html#id2

[vstinner]

The only user I found is this.
https://foss.heptapod.net/pypy/cffi/-/blob/cea8f1260587a4cf6ad230a00148cabea0f61572/demo/_curses.py#L972

@methane: Did you check for PyCurses_API and PyCurses_API_pointers usage?

[shihai1991]

The only user I found is this.
https://foss.heptapod.net/pypy/cffi/-/blob/cea8f1260587a4cf6ad230a00148cabea0f61572/demo/_curses.py#L972

@methane: Did you check for PyCurses_API and PyCurses_API_pointers usage?

I use https://searchcode.com/ to check who will use it. But I am not find the useful info in here.

[encukou]

Hum, this change is backward incompatible. I don't know how to proceed.

Well, PEP 387 is quite clear on this one, I think. PyCurses_API is obviously an API, so it can't be changed without a deprecation warning period.
IMO, this should be done by adding a new capsule and deprecating the old static one.

[shihai1991]

Hum, this change is backward incompatible. I don't know how to proceed.

Well, PEP 387 is quite clear on this one, I think. PyCurses_API is obviously an API, so it can't be changed without a deprecation warning period.
IMO, this should be done by adding a new capsule and deprecating the old static one.

Hm, it's more friendly to users. What's your suggestion? victor :) @vstinner

[serhiy-storchaka]

Why do you want to do this?

If we will do that, I think it is safe to replace an array with a structure as long as offsets of structure fields matches offsets of array items. I believe it is true on all supported platforms, because all fields are pointers. PyCurses_API_pointers should be kept for compatibility (but deprecated).

[vstinner]

Why do you want to do this?

I proposed this change (and @shihai1991 implemented it) since I don't see a raw array of pointers as an "API".

If we will do that, I think it is safe to replace an array with a structure as long as offsets of structure fields matches offsets of array items. I believe it is true on all supported platforms, because all fields are pointers. PyCurses_API_pointers should be kept for compatibility (but deprecated).

Even if PyCurses_API_pointers (4) is part of the public Include/py_curses.h header file (and it doesn't exclude anything from the limited C API), it seems like the API is mostly used through these 4 macros:

#define PyCursesWindow_Type (*(PyTypeObject *) PyCurses_API[0])
#define PyCursesSetupTermCalled  {if (! ((int (*)(void))PyCurses_API[1]) () ) return NULL;}
#define PyCursesInitialised      {if (! ((int (*)(void))PyCurses_API[2]) () ) return NULL;}
#define PyCursesInitialisedColor {if (! ((int (*)(void))PyCurses_API[3]) () ) return NULL;}

Not directly through static void **PyCurses_API;.

Maybe this API was only exposed for the _curses_panel module and is not intended to be used outside Python.

[vstinner]

Note: Include/py_curses.h is not included by Python.h.

[vstinner]

(oops, I closed the PR by mistake.)

[github-actions]

This PR is stale because it has been open for 30 days with no activity.

[arhadthedev]

I will rebase it tomorrow.

Could you target Doc/whatsnew/3.13.rst, please? 3.12 no longer accepts new features because of final preparations for 3.12b1.

[vstinner]

The least risky approach is to:

• Add a new internal C API, maybe using a struct rather than an array.
• Deprecate the old C API for 2 Python releases.

[shihai1991]

I will rebase it tomorrow.

Could you target Doc/whatsnew/3.13.rst, please? 3.12 no longer accepts new features because of final preparations for 3.12b1.

So 3.12 is prepare to release? I missed a lot of things recently.

[arhadthedev]

So 3.12 is prepare to release? I missed a lot of things recently.

Moreover, its release date was moved (python/peps#3139) from this Monday to May 22.

[erlend-aasland]

So 3.12 is prepare to release? I missed a lot of things recently.

No, only the beta (feature freeze). The release is not until this fall.

Anyway, I'm not sure how PEP-387 plays with stuff that's not exposed by Python.h.

[shihai1991]

So 3.12 is prepare to release? I missed a lot of things recently.

Moreover, its release date was moved (python/peps#3139) from this Monday to May 22.

I will rebase it tomorrow.

Could you target Doc/whatsnew/3.13.rst, please? 3.12 no longer accepts new features because of final preparations for 3.12b1.

Hi, I updated this PR(add the internal APIs) and the old APIs in py_curses.h hasn't been removed. So I think I add a note in 3.12 will be ok?

[arhadthedev]

So I think I add a note in 3.12 will be ok?

Probably yes, however, it's up to the core developers to decide.

Tests / Check if generated files are up to date (pull_request) Failing after 7m

checking analysis results...
Include/internal/pycore_curses.h   	-                                  	PyCurses_C_API                          	> not supported (mutable)           	static PyCurses_CAPI*
-------------------------
total failures: 1
done checking
Categorized by storage:


static-module-global
  Include/internal/pycore_curses.h   	-                                  	PyCurses_C_API
subtotal: 1

@erlend-aasland Should we store the new PyCurses_CAPI in the module state or the interpreter state?

[shihai1991]

@erlend-aasland Should we store the new PyCurses_CAPI in the module state or the interpreter state?

It's not common variable in interpreter(just the curses_panel extension module use this Capsule API), so saved in interpreter state is OK.

[erlend-aasland]

It's not common variable in interpreter(just the curses_panel extension module use this Capsule API), so saved in interpreter state is OK.

I assume you meant module state, no?

[shihai1991]

It's not common variable in interpreter(just the curses_panel extension module use this Capsule API), so saved in interpreter state is OK.

I assume you meant module state, no?

Oh, thanks for correcting my wrong writing.

In addition, Use the ignored.csv to ignore the warning maybe OK in this case.

[github-actions]

This PR is stale because it has been open for 30 days with no activity.

[read-the-docs-community]

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