If you don't know?

• pip install -e . or uv sync
• Edit python files
• Changes show up immediately (± importlib.reload)

scikit-build-core caveat

• Edit C/C++/CMake source files
• Changes show up
  • Since 1.0: just call loader.rebuild()

Example: pyproject.toml

[build-system]
requires = ["scikit-build-core>=1"]
build-backend = "scikit_build_core.build"

[project]
name = "example"
version = "0.1.0"

[tool.scikit-build]
build-dir = "build"

Example: python/example/__init__.py

from importlib.resources import files


def show_file():
    cmake_file = files("example") / "file.txt"
    print(cmake_file.read_text())

Example: CMakeLists.txt

cmake_minimum_required(VERSION 3.15...4.3)
project(${SKBUILD_PROJECT_NAME} LANGUAGES NONE)

add_custom_target(copy_file ALL
  COMMAND ${CMAKE_COMMAND} -E copy
    ${CMAKE_CURRENT_SOURCE_DIR}/source.txt
    ${CMAKE_CURRENT_BINARY_DIR}/file.txt
)

install(FILES
  ${CMAKE_CURRENT_BINARY_DIR}/file.txt
  DESTINATION ${SKBUILD_PROJECT_NAME}
 )

Example: It works!

>>> import importlib.util
>>> importlib.util.find_spec("example").loader.rebuild()
Running cmake --build & --install in /home/cle/tmp/simple-py/build
[1/1] cd build && /usr/bin/cmake -E copy source.txt build/file.txt
-- Install configuration: "Release"
-- Installing: .venv/lib64/python3.14/site-packages/example/file.txt
>>> import example
>>> example.show_file()
Off to the races!

Two editable.mode: redirect

• CMake build in predictable build-dir (if you include it )
• _editable_skbc_{project}.(py|pth) point <pkg>.<module> to build-dir or source-dir

Actually forget about: inplace

• If you think you need it
  • Do you really need it?
• If you're sure you need it
  • Have you exhausted all options?
• If inplace is really what you want
  • Why?

Why avoid inplace

• build-dir == source-dir
  • CMakeCache.txt etc.
  • We cannot help you delete build files
• You have to put build artifacts in correct place

• Since 1.0: try editable.rebuild-dir instead

Tips and pitfalls

Dependencies in build-system.requires

• CMake dependencies (pybind11) DO NOT persist
• Make sure you use --no-build-isolation

  $ pip install --no-build-isolation -e .
  $ uv sync --no-build-isolation
  

Tips and pitfalls

Use importlib.resources

>>> from pathlib import Path
>>> lib = Path(__file__).parent / "my_lib.so"
>>> lib.open()
FileNotFoundError: [Errno 2] No such file or directory: 'my_lib.so'

my_lib.so is in build-dir, test.py is in source-dir

Tips and pitfalls

Use importlib.resources

>>> from importlib.resources import files
>>> lib = files("my_pkg") / "my_lib.so"
>>> lib.open()

Tips and pitfalls

1.0 changes

• importlib.util.find_spec("<pkg>").loader.rebuild(): rebuild on demand
• editable.rebuild-dir: specify where to install
• importlib.resources should work properly (custom implementation)

What to expect in 1.1?

• editable.mode without install
  • better support for debuggers and code coverage