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gh-129342: Explain how to replace Py_GetProgramName() in C #129361

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Feb 3, 2025
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gh-129342: Explain how to replace Py_GetProgramName() in C #129361

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gh-129342: Explain how to replace Py_GetProgramName() in C
vstinner Jan 27, 2025
e7de63c
Remove PySys_GetObject()
vstinner Jan 28, 2025
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27 changes: 18 additions & 9 deletions Doc/c-api/init.rst
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Expand Up @@ -622,7 +622,8 @@ Process-wide parameters
It now returns ``NULL`` if called before :c:func:`Py_Initialize`.

.. deprecated-removed:: 3.13 3.15
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I think that we should postpone hard deprecation until there is a non-deprecated replacement that works in all maintained Python versions.

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PySys_GetObject() works on all Python versions, it's not deprecated: https://docs.python.org/dev/c-api/sys.html#c.PySys_GetObject

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You can use pythoncapi-compat to get PyConfig_Get() on Python 3.13 and older.

Get :data:`sys.executable` instead.
Use ``PySys_GetObject("executable")`` (:data:`sys.executable`) or
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I think that PyConfig_Get("executable") is more preferable in a new code, isn't it?

PySys_GetObject() will be deprecated in future (it returns a borrowed reference and silences errors).

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PySys_GetObject() works on all Python versions, whereas PyConfig_Get() is new in Python 3.14. The note can be updated once PySys_GetObject() will be deprecated.

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We should suggest first what will work in future versions. We do not want users to rewrite the same code twice (and curse us twice).

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PySys_GetObject() works on all Python versions, whereas PyConfig_Get() is new in Python 3.14.

I don't understand; this PR is for the 3.14 docs, so it should be ok to mention new-in-3.14 APIs here, no?

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If possible, I would prefer to provide a replacement working on old Python versions as well.

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I updated the PR to use only PyConfig_Get().

``PyConfig_Get("executable")`` instead.


.. c:function:: wchar_t* Py_GetPrefix()
Expand All @@ -644,8 +645,11 @@ Process-wide parameters
It now returns ``NULL`` if called before :c:func:`Py_Initialize`.

.. deprecated-removed:: 3.13 3.15
Get :data:`sys.base_prefix` instead, or :data:`sys.prefix` if
:ref:`virtual environments <venv-def>` need to be handled.
Use ``PySys_GetObject("base_prefix")`` (:data:`sys.base_prefix`) or
``PyConfig_Get("base_prefix")`` instead. Use
``PySys_GetObject("prefix")`` (:data:`sys.prefix`) or
``PyConfig_Get("prefix")`` if :ref:`virtual environments <venv-def>` need
to be handled.


.. c:function:: wchar_t* Py_GetExecPrefix()
Expand Down Expand Up @@ -690,8 +694,11 @@ Process-wide parameters
It now returns ``NULL`` if called before :c:func:`Py_Initialize`.

.. deprecated-removed:: 3.13 3.15
Get :data:`sys.base_exec_prefix` instead, or :data:`sys.exec_prefix` if
:ref:`virtual environments <venv-def>` need to be handled.
Use ``PySys_GetObject("base_exec_prefix")``
(:data:`sys.base_exec_prefix`) or ``PyConfig_Get("base_exec_prefix")``
instead. Use ``PySys_GetObject("exec_prefix")`` (:data:`sys.exec_prefix`)
or ``PyConfig_Get("exec_prefix")`` if :ref:`virtual environments
<venv-def>` need to be handled.


.. c:function:: wchar_t* Py_GetProgramFullPath()
Expand All @@ -712,7 +719,8 @@ Process-wide parameters
It now returns ``NULL`` if called before :c:func:`Py_Initialize`.

.. deprecated-removed:: 3.13 3.15
Get :data:`sys.executable` instead.
Use ``PySys_GetObject("executable")`` (:data:`sys.executable`) or
``PyConfig_Get("executable")`` instead.


.. c:function:: wchar_t* Py_GetPath()
Expand Down Expand Up @@ -740,7 +748,8 @@ Process-wide parameters
It now returns ``NULL`` if called before :c:func:`Py_Initialize`.

.. deprecated-removed:: 3.13 3.15
Get :data:`sys.path` instead.
Use ``PySys_GetObject("path")`` (:data:`sys.path`)
or ``PyConfig_Get("module_search_paths")`` instead.


.. c:function:: const char* Py_GetVersion()
Expand Down Expand Up @@ -926,8 +935,8 @@ Process-wide parameters
It now returns ``NULL`` if called before :c:func:`Py_Initialize`.

.. deprecated-removed:: 3.13 3.15
Get :c:member:`PyConfig.home` or :envvar:`PYTHONHOME` environment
variable instead.
Use :c:func:`PyConfig_Get("home") <PyConfig_Get>`
or the :envvar:`PYTHONHOME` environment variable instead.


.. _threads:
Expand Down
28 changes: 19 additions & 9 deletions Doc/deprecations/c-api-pending-removal-in-3.15.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -10,22 +10,30 @@ Pending removal in Python 3.15
:c:func:`PyWeakref_GetRef` on Python 3.12 and older.
* :c:type:`Py_UNICODE` type and the :c:macro:`!Py_UNICODE_WIDE` macro:
Use :c:type:`wchar_t` instead.
* Python initialization functions:
* Python initialization functions, deprecated in Python 3.13:

* :c:func:`PySys_ResetWarnOptions`:
Clear :data:`sys.warnoptions` and :data:`!warnings.filters` instead.
* :c:func:`Py_GetExecPrefix`:
Get :data:`sys.base_exec_prefix` and :data:`sys.exec_prefix` instead.
Use ``PySys_GetObject("base_exec_prefix")`` (:data:`sys.base_exec_prefix`)
or ``PyConfig_Get("base_exec_prefix")`` instead. Use
``PySys_GetObject("exec_prefix")`` (:data:`sys.exec_prefix`) or
``PyConfig_Get("exec_prefix")`` if :ref:`virtual environments <venv-def>`
need to be handled.
* :c:func:`Py_GetPath`:
Get :data:`sys.path` instead.
Use ``PySys_GetObject("path")`` (:data:`sys.path`)
or ``PyConfig_Get("module_search_paths")`` instead.
* :c:func:`Py_GetPrefix`:
Get :data:`sys.base_prefix` and :data:`sys.prefix` instead.
Use ``PySys_GetObject("base_prefix")`` (:data:`sys.base_prefix`) or
``PyConfig_Get("base_prefix")`` instead. Use ``PySys_GetObject("prefix")``
(:data:`sys.prefix`) or ``PyConfig_Get("prefix")`` if :ref:`virtual
environments <venv-def>` need to be handled.
* :c:func:`Py_GetProgramFullPath`:
Get :data:`sys.executable` instead.
Use ``PySys_GetObject("executable")`` (:data:`sys.executable`)
or ``PyConfig_Get("executable")`` instead.
* :c:func:`Py_GetProgramName`:
Get :data:`sys.executable` instead.
Use ``PySys_GetObject("executable")`` (:data:`sys.executable`)
or ``PyConfig_Get("executable")`` instead.
* :c:func:`Py_GetPythonHome`:
Get :c:func:`PyConfig_Get("home") <PyConfig_Get>`
Use :c:func:`PyConfig_Get("home") <PyConfig_Get>`
or the :envvar:`PYTHONHOME` environment variable instead.

See also the :c:func:`PyConfig_Get` function.
Expand All @@ -40,6 +48,8 @@ Pending removal in Python 3.15
Set :c:member:`PyConfig.program_name` instead.
* :c:func:`!Py_SetPythonHome()`:
Set :c:member:`PyConfig.home` instead.
* :c:func:`PySys_ResetWarnOptions`:
Clear :data:`sys.warnoptions` and :data:`!warnings.filters` instead.

The :c:func:`Py_InitializeFromConfig` API should be used with
:c:type:`PyConfig` instead.
Expand Down
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