Add conan-py-build example (#231)

* add conan-py-build example

* wip

* wip

Author: czoido

examples/extensions/README.md

@@ -19,3 +19,7 @@
 #### [Sigstore (cosign)](plugins/sigstore_sign)
 
 - Sign and verify packages with [Sigstore](https://www.sigstore.dev/) using [cosign](https://github.com/sigstore/cosign).
+
+### [Python extension built with conan-py-build](python_build_backend)
+
+- Learn how to build a Python package with a C/C++ extension whose dependencies are managed by Conan through [conan-py-build](https://github.com/conan-io/conan-py-build). [Docs](https://docs.conan.io/2/integrations/python.html)

examples/extensions/python_build_backend/.gitignore

@@ -0,0 +1 @@
+dist/

examples/extensions/python_build_backend/CMakeLists.txt

@@ -0,0 +1,12 @@
+cmake_minimum_required(VERSION 3.15)
+project(myadder LANGUAGES CXX)
+
+find_package(Python3 REQUIRED COMPONENTS Interpreter Development.Module)
+set(PYBIND11_FINDPYTHON ON)
+find_package(pybind11 CONFIG REQUIRED)
+find_package(fmt REQUIRED)
+
+pybind11_add_module(_core src/myadder.cpp)
+target_link_libraries(_core PRIVATE pybind11::module fmt::fmt)
+
+install(TARGETS _core DESTINATION myadder)

examples/extensions/python_build_backend/LICENSE

@@ -0,0 +1,27 @@
+The MIT License (MIT)
+
+Copyright (c) 2026 JFrog LTD
+
+
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.

examples/extensions/python_build_backend/README.md

@@ -0,0 +1,35 @@
+# Python extension built with conan-py-build
+
+A minimal example of a Python package with a C++ extension (built with
+**pybind11** and **fmt**) where all the C++ dependencies are managed by
+Conan through [`conan-py-build`](https://github.com/conan-io/conan-py-build),
+a PEP 517 build backend.
+
+- Conan blog post: https://blog.conan.io/cpp/conan/python/2026/05/05/Introducing-conan-py-build.html
+- `conan-py-build` documentation: https://conan-py-build.conan.io
+
+## How it works
+
+- `pyproject.toml` declares `conan-py-build` as the build backend.
+- `conanfile.py` is a regular Conan recipe declaring `pybind11` and `fmt`
+  as requirements, and building the extension with CMake using the same
+  Python interpreter as `pip`.
+- `CMakeLists.txt` builds the `_core` extension module and installs it
+  into a `myadder` directory, matching the Python package name so the
+  compiled module ends up next to `__init__.py` in the resulting wheel.
+- `python/myadder/__init__.py` re-exports the `add()` function from the
+  compiled `_core` module.
+
+## Build and test
+
+```bash
+git clone https://github.com/conan-io/examples2.git
+cd examples2/examples/extensions/python_build_backend
+
+pip wheel . -w dist/
+
+pip install dist/myadder-*.whl
+python -c "from myadder import add; add(2, 3)"
+```
+
+This prints `2 + 3 = 5` in bold green (via `fmt`'s color support) and returns `5.0`.

examples/extensions/python_build_backend/ci_test_example.py

@@ -0,0 +1,23 @@
+import glob
+import os
+import shutil
+
+from test.examples_tools import run
+
+# ############# Example ################
+print("Build a Python C++ extension (pybind11 + fmt) with conan-py-build")
+
+run("pip wheel . -w dist/ -v")
+
+wheels = glob.glob(os.path.join("dist", "myadder-*.whl"))
+assert wheels, "No wheel was generated"
+
+run(f"pip install --force-reinstall {wheels[0]}")
+
+output = run('python -c "from myadder import add; add(2, 3)"')
+assert "2 + 3 = 5" in output
+
+run("pip uninstall myadder -y")
+
+shutil.rmtree("dist", ignore_errors=True)
+shutil.rmtree("build", ignore_errors=True)

examples/extensions/python_build_backend/conanfile.py

@@ -0,0 +1,33 @@
+import sys
+
+from conan import ConanFile
+from conan.tools.cmake import CMake, CMakeDeps, CMakeToolchain, cmake_layout
+
+
+class MyAdderConan(ConanFile):
+    name = "myadder"
+    settings = "os", "compiler", "build_type", "arch"
+
+    def layout(self):
+        cmake_layout(self)
+
+    def requirements(self):
+        self.requires("pybind11/3.0.1")
+        self.requires("fmt/12.1.0")
+
+    def generate(self):
+        # Keep CMake on the same Python interpreter pip uses
+        tc = CMakeToolchain(self)
+        tc.cache_variables["Python3_EXECUTABLE"] = sys.executable
+        tc.generate()
+        deps = CMakeDeps(self)
+        deps.generate()
+
+    def build(self):
+        cmake = CMake(self)
+        cmake.configure()
+        cmake.build()
+
+    def package(self):
+        cmake = CMake(self)
+        cmake.install()

examples/extensions/python_build_backend/pyproject.toml

@@ -0,0 +1,14 @@
+[build-system]
+requires = ["conan-py-build"]
+build-backend = "conan_py_build.build"
+
+[project]
+name = "myadder"
+version = "0.1.0"
+description = "A simple Python package with a C++ extension (pybind11 + fmt) built through Conan"
+license = "MIT"
+license-files = ["LICENSE"]
+requires-python = ">=3.8"
+
+[tool.conan-py-build.wheel]
+packages = ["python/myadder"]

examples/extensions/python_build_backend/python/myadder/__init__.py

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+from myadder._core import add
+
+__all__ = ["add"]

examples/extensions/python_build_backend/src/myadder.cpp

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+#include <pybind11/pybind11.h>
+#include <fmt/core.h>
+#include <fmt/color.h>
+
+namespace py = pybind11;
+
+double add(double a, double b) {
+    double result = a + b;
+    fmt::print(fg(fmt::color::green) | fmt::emphasis::bold,
+               "{} + {} = {}\n", a, b, result);
+    return result;
+}
+
+PYBIND11_MODULE(_core, m) {
+    m.doc() = "Simple Python extension using fmt via Conan.";
+    m.def("add", &add, "Add two numbers and print the result formatted with fmt.",
+          py::arg("a"), py::arg("b"));
+}