From 762c9f95ae31956e8f6b93b6b52b60fb322bdf85 Mon Sep 17 00:00:00 2001 From: Barry Warsaw Date: Wed, 6 May 2026 04:22:54 -0700 Subject: [PATCH] gh-148641: Flesh out PEP 829 for What's New (#149347) Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com> --- Doc/whatsnew/3.15.rst | 27 ++++++++++++++++++++++++++- 1 file changed, 26 insertions(+), 1 deletion(-) diff --git a/Doc/whatsnew/3.15.rst b/Doc/whatsnew/3.15.rst index 3cf69718e63..1a5e5fe2fc0 100644 --- a/Doc/whatsnew/3.15.rst +++ b/Doc/whatsnew/3.15.rst @@ -81,6 +81,7 @@ Summary -- Release highlights ` * :pep:`686`: :ref:`Python now uses UTF-8 as the default encoding ` +* :pep:`829`: :ref:`Package startup configuration files ` * :pep:`728`: :ref:`TypedDict with typed extra items ` * :pep:`747`: :ref:`Annotating type forms with TypeForm ` @@ -94,7 +95,6 @@ Summary -- Release highlights * :ref:`Improved error messages ` * :ref:`The official Windows 64-bit binaries now use the tail-calling interpreter ` -* :pep:`829`: Package Startup Configuration Files New features ============ @@ -452,6 +452,31 @@ agen() for x in a)``. (Contributed by Adam Hartz in :gh:`143055`.) +.. _whatsnew315-startup-files: + +:pep:`829`: Package startup configuration files +----------------------------------------------- + +Loaded by the :mod:`site` module when ``-S`` is not given, :ref:`.pth files ` +can contain lines that both extend :data:`sys.path` and execute arbitrary code +when the line starts with ``import`` (followed by a space or tab). The latter +functionality can be problematic, since it is difficult to know exactly what +gets executed when Python starts up. + +As a step towards improving the ability to audit pre-start executable code, +Python 3.15 introduces :ref:`.start files ` which contain entry point +specifications of the form ``pkg.mod:callable`` where ``pkg.mod`` is the +import path to the given callable. When Python starts up, the callable is +located and called with no arguments. + +``import`` lines in :file:`.pth` files are silently deprecated. When a +matching :file:`.start` file is found, ``import`` lines in :file:`.pth` files +are ignored. There is no change to :data:`sys.path` extension lines in +:file:`.pth` files. + +(Contributed by Barry Warsaw in :gh:`148641`.) + + .. _whatsnew315-abi3t: :pep:`803` -- Stable ABI for Free-Threaded Builds