Build a single abi3 (Stable ABI) wheel for CPython 3.11+, release 1.0.0

Target the CPython Limited API via scikit-build-core's wheel.py-api so a single
abi3 wheel per platform covers CPython 3.11 and later. CPython 3.10 still
receives a regular, version-specific wheel, preserving support for all
currently-supported Python versions.

- pyproject.toml: set wheel.py-api = "cp311" and raise the scikit-build-core
  build requirement to >=0.11 for the SKBUILD_SABI_COMPONENT and
  SKBUILD_SABI_VERSION variables
- CMakeLists.txt: request the Development.SABIModule component and pass USE_SABI
  to python_add_library when targeting the Stable ABI, so FindPython defines
  Py_LIMITED_API and names the extension cutil.abi3.so
- README: document the abi3 wheels and the 3.11 floor (and fix a stray
  reference to Simplification)
- Bump version to 1.0.0 (CITATION.cff and pyproject.toml; uv.lock follows)

The floor is 3.11 because the typed memoryviews used in cutil.pyx are only
available under the Limited API from CPython 3.11 onwards. The Rust lonlat_bng
FFI library is a pure C-ABI dependency and is unaffected. cibuildwheel 4.0.0
handles abi3 wheels automatically (build once, test on all later versions, run
abi3audit after repair), so no CI changes are required.

Author: urschrei

CITATION.cff

@@ -7,12 +7,12 @@ authors:
     given-names: Stephan
     orcid: "https://orcid.org/0000-0003-4379-2450"
 title: "Convertbng"
-date-released: 2021-12-12
+date-released: 2026-06-08
 doi: "10.5281/zenodo.5774931"
 keywords:
   - geo
   - gis
   - polyline
 license: BlueOak-1.0.0
 repository-code: "https://github.com/urschrei/convertbng"
-version: "0.2.72"
+version: "1.0.0"

CMakeLists.txt

@@ -8,9 +8,12 @@ project(
 set(convertbng_SRC_DIR "${CMAKE_CURRENT_SOURCE_DIR}/src/convertbng")
 
 # Find Python
+# ${SKBUILD_SABI_COMPONENT} resolves to "Development.SABIModule" when
+# scikit-build-core is targeting the Stable ABI (see wheel.py-api in
+# pyproject.toml) and to an empty string otherwise (e.g. CPython 3.10, PyPy).
 find_package(
   Python
-  COMPONENTS Interpreter Development.Module NumPy
+  COMPONENTS Interpreter Development.Module NumPy ${SKBUILD_SABI_COMPONENT}
   REQUIRED)
 include(UseCython)
 
@@ -24,8 +27,17 @@ cython_transpile(
   CYTHON_ARGS -I "${convertbng_SRC_DIR}"
 )
 
-# Create the extension module
-python_add_library(cutil MODULE "${cutil}" WITH_SOABI)
+# Create the extension module.
+# When targeting the Stable ABI, ${SKBUILD_SABI_VERSION} holds the minimum
+# CPython version (e.g. "3.11"); passing it via USE_SABI makes FindPython define
+# Py_LIMITED_API and name the module cutil.abi3.so. When it is empty (CPython
+# 3.10, PyPy) we fall back to a regular, version-specific extension module.
+if(NOT "${SKBUILD_SABI_VERSION}" STREQUAL "")
+  message(STATUS "Building cutil against the Limited API for ${SKBUILD_SABI_VERSION}")
+  python_add_library(cutil MODULE "${cutil}" WITH_SOABI USE_SABI ${SKBUILD_SABI_VERSION})
+else()
+  python_add_library(cutil MODULE "${cutil}" WITH_SOABI)
+endif()
 
 # Set include directories
 target_include_directories(cutil PRIVATE

README.md

@@ -27,7 +27,9 @@ To build from the sdist, download the release archive for your platform from the
 Changes in `pyx` and `pxd` files, and the Rust library and header will bust the cache, triggering a rebuild when `uv` commands are run.
 
 ### Supported Python Versions
-Simplification supports all [_currently_ supported Python versions](https://devguide.python.org/versions/).
+convertbng supports all [_currently_ supported Python versions](https://devguide.python.org/versions/).
+
+Binary wheels target the CPython [Stable ABI](https://docs.python.org/3/c-api/stable.html) (`abi3`): a single `abi3` wheel per platform covers CPython 3.11 and later, while CPython 3.10 receives a standard version-specific wheel.
 
 ### Supported Platforms
 - Linux (`manylinux`-compatible) x86_64 and aarch64

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "convertbng"
-version = "0.7.12"
+version = "1.0.0"
 description = "Fast lon, lat to and from ETRS89 and BNG (OSGB36) using the OS OSTN15 transform via Rust FFI"
 readme = "README.md"
 requires-python = ">=3.10"
@@ -39,10 +39,15 @@ dev = [
 [tool.scikit-build]
 minimum-version = "build-system.requires"
 wheel.packages = ["src/convertbng"]
+# Build a single Stable ABI (abi3) wheel for CPython 3.11+. Typed memoryviews,
+# which cutil.pyx relies on, are only available under the Limited API from
+# CPython 3.11 onwards, so that is the floor. CPython 3.10 still receives a
+# regular, version-specific wheel.
+wheel.py-api = "cp311"
 
 [build-system]
 requires = [
-    "scikit-build-core>=0.10",
+    "scikit-build-core>=0.11",
     "numpy >= 2.0.0",
     "cython >= 3.1.0",
     "cython-cmake"