PEP 803: add comments from David Hewitt and Ralf Gommers

Author: ngoldbaum

peps/pep-0803.rst

@@ -112,8 +112,8 @@ on Discourse for a free-threaded stable ABI:
     long as we have O(1) builds, that’s ok. What we can’t/won’t do is O(n)
     where we need new builds for every Python release.
 
-When one of the PEP authors asked him in the ``#pyca`` Libera IRC channel, he
-said:
+When one of the PEP authors asked Alex in the ``#pyca`` Libera IRC channel for
+his current opinion, he said:
 
     One other thing I'll note that's *really* valuable about ``abi3`` is that it
     means our old wheels keep working for new Python versions. If we have
@@ -149,9 +149,51 @@ free-threaded build, he commented:
     I will revisit this again once Python 3.15 is released. Hopefully the ABI
     will be stable (or even better, free-threading will be the default).
 
-These two libraries -- cryptography and moocore -- both have low maintainer
-bandwidth and would like to have a stable ABI on the free-threaded build they
-can use to ship wheels and reduce their maintenance burden.
+Pydantic
+^^^^^^^^
+
+Pydantic maintainer David Hewitt `observed
+<https://github.com/python/peps/pull/4831#issuecomment-3972183807>`_:
+
+    Pydantic distributes wheels for a native core built using Rust & PyO3. The
+    latest release of `pydantic-core distributed
+    <https://pypi.org/project/pydantic_core/2.42.0/#files>`_ 112 wheels and
+    this number is set to grow as more environments are to be added
+    (e.g. Android, iOS, wasm). Pydantic has historically not distributed using
+    the stable ABI because the feature set was too immature. Much Pydantic
+    functionality interacts with Python objects via the C API in hot loops so
+    performance is key concern. As the stable ABI matures it will be ideal for
+    Pydantic to switch tier 2 platforms to the stable ABI (and perhaps
+    eventually tier 1 platforms too), which will significantly reduce the
+    number of wheels to build, test, and distribute.
+
+    I would like to highlight that if free-threading does not adopt a stable
+    ABI, all the benefits above will be lost when free-threading becomes the
+    default and only build (which seems the expected long-term plan).
+
+
+SciPy
+^^^^^
+
+The SciPy project uploaded 60 version-specific wheel files for its `last release
+<https://pypi.org/project/scipy/1.17.1/#files>`_ to support four different
+CPython versions. They do not upload wheels for PyPy.
+
+When asked about this proposal, SciPy steering council chair Ralf Gommers `said
+<https://github.com/python/peps/pull/4831#issuecomment-3968143777>`_:
+
+    SciPy and a number of other projects in the scientific Python ecosystem
+    are quite interested in starting to use the Stable ABI, in particular to
+    reduce the maintenance load of `providing more wheels
+    <https://pypackaging-native.github.io/meta-topics/user_expectations_wheels/>`_.
+    With recent CPython, Cython and NumPy releases, this now seems
+    possible. The performance costs seem acceptable and small, although we'll
+    only really build confidence in that assessment after having made the
+    switch.
+
+By providing a new free-threaded stable ABI in Python 3.15, SciPy will not have
+to consider the lack of a stable ABI on the free-threaded build as the project
+considers switching to stable API wheels.
 
 
 Bindings generators
@@ -169,7 +211,26 @@ defined in CPython's ``main`` branch, indicates that PyO3, CFFI, and Cython will
 all work with PEP 803 using packaging tools that have been patched to account
 for an ``abi3.abi3t`` tag.
 
-Cython maintainer David Woods `says
+PyO3 maintainer David Hewitt `said
+<https://github.com/python/peps/pull/4831#issuecomment-3972183807>`_ in
+support of this proposal:
+
+    PyO3 greatly benefits from having a stable ABI - one of the biggest
+    challenges for the framework is the need to abstract over a wide range of
+    Python / OS / CPU / environment combinations. We also offer the
+    possibility to build with the stable ABI for each of these environments
+    (targeting a given minimum Python version's stable ABI). The goal is
+    always that all functionality PyO3 offers works the same on all these
+    combinations (sometimes with a Python version floor to access certain
+    features). We currently support Python 3.7+. All functionality added to
+    the stable ABI is a very welcome promise that PyO3 will not need to
+    introduce further conditional code to support a given feature. In the long
+    run this makes it possible for PyO3 to simplify code paths as support for
+    older Python versions is dropped, helping to keep maintenance burden under
+    control.
+
+When asked to comment about this proposal, Cython
+maintainer David Woods `said
 <https://github.com/cython/cython/issues/7399#issuecomment-3947605797>`_:
 
     Cython doesn't have huge problems with the number of wheels we distribute