diff options
Diffstat (limited to '3rdparty/pybind11/docs/compiling.rst')
| -rw-r--r-- | 3rdparty/pybind11/docs/compiling.rst | 455 |
1 files changed, 398 insertions, 57 deletions
diff --git a/3rdparty/pybind11/docs/compiling.rst b/3rdparty/pybind11/docs/compiling.rst index c50c7d8a..f26e6cf6 100644 --- a/3rdparty/pybind11/docs/compiling.rst +++ b/3rdparty/pybind11/docs/compiling.rst @@ -3,6 +3,8 @@ Build systems ############# +.. _build-setuptools: + Building with setuptools ======================== @@ -13,6 +15,203 @@ the [python_example]_ repository. .. [python_example] https://github.com/pybind/python_example +A helper file is provided with pybind11 that can simplify usage with setuptools. + +To use pybind11 inside your ``setup.py``, you have to have some system to +ensure that ``pybind11`` is installed when you build your package. There are +four possible ways to do this, and pybind11 supports all four: You can ask all +users to install pybind11 beforehand (bad), you can use +:ref:`setup_helpers-pep518` (good, but very new and requires Pip 10), +:ref:`setup_helpers-setup_requires` (discouraged by Python packagers now that +PEP 518 is available, but it still works everywhere), or you can +:ref:`setup_helpers-copy-manually` (always works but you have to manually sync +your copy to get updates). + +An example of a ``setup.py`` using pybind11's helpers: + +.. code-block:: python + + from glob import glob + from setuptools import setup + from pybind11.setup_helpers import Pybind11Extension + + ext_modules = [ + Pybind11Extension( + "python_example", + sorted(glob("src/*.cpp")), # Sort source files for reproducibility + ), + ] + + setup( + ..., + ext_modules=ext_modules + ) + +If you want to do an automatic search for the highest supported C++ standard, +that is supported via a ``build_ext`` command override; it will only affect +``Pybind11Extensions``: + +.. code-block:: python + + from glob import glob + from setuptools import setup + from pybind11.setup_helpers import Pybind11Extension, build_ext + + ext_modules = [ + Pybind11Extension( + "python_example", + sorted(glob("src/*.cpp")), + ), + ] + + setup( + ..., + cmdclass={"build_ext": build_ext}, + ext_modules=ext_modules + ) + +Since pybind11 does not require NumPy when building, a light-weight replacement +for NumPy's parallel compilation distutils tool is included. Use it like this: + +.. code-block:: python + + from pybind11.setup_helpers import ParallelCompile + + # Optional multithreaded build + ParallelCompile("NPY_NUM_BUILD_JOBS").install() + + setup(...) + +The argument is the name of an environment variable to control the number of +threads, such as ``NPY_NUM_BUILD_JOBS`` (as used by NumPy), though you can set +something different if you want. You can also pass ``default=N`` to set the +default number of threads (0 will take the number of threads available) and +``max=N``, the maximum number of threads; if you have a large extension you may +want set this to a memory dependent number. + +If you are developing rapidly and have a lot of C++ files, you may want to +avoid rebuilding files that have not changed. For simple cases were you are +using ``pip install -e .`` and do not have local headers, you can skip the +rebuild if a object file is newer than it's source (headers are not checked!) +with the following: + +.. code-block:: python + + from pybind11.setup_helpers import ParallelCompile, naive_recompile + + SmartCompile("NPY_NUM_BUILD_JOBS", needs_recompile=naive_recompile).install() + + +If you have a more complex build, you can implement a smarter function and pass +it to ``needs_recompile``, or you can use [Ccache]_ instead. ``CXX="cache g++" +pip install -e .`` would be the way to use it with GCC, for example. Unlike the +simple solution, this even works even when not compiling in editable mode, but +it does require Ccache to be installed. + +Keep in mind that Pip will not even attempt to rebuild if it thinks it has +already built a copy of your code, which it deduces from the version number. +One way to avoid this is to use [setuptools_scm]_, which will generate a +version number that includes the number of commits since your last tag and a +hash for a dirty directory. Another way to force a rebuild is purge your cache +or use Pip's ``--no-cache-dir`` option. + +.. [Ccache] https://ccache.dev + +.. [setuptools_scm] https://github.com/pypa/setuptools_scm + +.. _setup_helpers-pep518: + +PEP 518 requirements (Pip 10+ required) +--------------------------------------- + +If you use `PEP 518's <https://www.python.org/dev/peps/pep-0518/>`_ +``pyproject.toml`` file, you can ensure that ``pybind11`` is available during +the compilation of your project. When this file exists, Pip will make a new +virtual environment, download just the packages listed here in ``requires=``, +and build a wheel (binary Python package). It will then throw away the +environment, and install your wheel. + +Your ``pyproject.toml`` file will likely look something like this: + +.. code-block:: toml + + [build-system] + requires = ["setuptools", "wheel", "pybind11==2.6.0"] + build-backend = "setuptools.build_meta" + +.. note:: + + The main drawback to this method is that a `PEP 517`_ compliant build tool, + such as Pip 10+, is required for this approach to work; older versions of + Pip completely ignore this file. If you distribute binaries (called wheels + in Python) using something like `cibuildwheel`_, remember that ``setup.py`` + and ``pyproject.toml`` are not even contained in the wheel, so this high + Pip requirement is only for source builds, and will not affect users of + your binary wheels. + +.. _PEP 517: https://www.python.org/dev/peps/pep-0517/ +.. _cibuildwheel: https://cibuildwheel.readthedocs.io + +.. _setup_helpers-setup_requires: + +Classic ``setup_requires`` +-------------------------- + +If you want to support old versions of Pip with the classic +``setup_requires=["pybind11"]`` keyword argument to setup, which triggers a +two-phase ``setup.py`` run, then you will need to use something like this to +ensure the first pass works (which has not yet installed the ``setup_requires`` +packages, since it can't install something it does not know about): + +.. code-block:: python + + try: + from pybind11.setup_helpers import Pybind11Extension + except ImportError: + from setuptools import Extension as Pybind11Extension + + +It doesn't matter that the Extension class is not the enhanced subclass for the +first pass run; and the second pass will have the ``setup_requires`` +requirements. + +This is obviously more of a hack than the PEP 518 method, but it supports +ancient versions of Pip. + +.. _setup_helpers-copy-manually: + +Copy manually +------------- + +You can also copy ``setup_helpers.py`` directly to your project; it was +designed to be usable standalone, like the old example ``setup.py``. You can +set ``include_pybind11=False`` to skip including the pybind11 package headers, +so you can use it with git submodules and a specific git version. If you use +this, you will need to import from a local file in ``setup.py`` and ensure the +helper file is part of your MANIFEST. + + +Closely related, if you include pybind11 as a subproject, you can run the +``setup_helpers.py`` inplace. If loaded correctly, this should even pick up +the correct include for pybind11, though you can turn it off as shown above if +you want to input it manually. + +Suggested usage if you have pybind11 as a submodule in ``extern/pybind11``: + +.. code-block:: python + + DIR = os.path.abspath(os.path.dirname(__file__)) + + sys.path.append(os.path.join(DIR, "extern", "pybind11")) + from pybind11.setup_helpers import Pybind11Extension # noqa: E402 + + del sys.path[-1] + + +.. versionchanged:: 2.6 + + Added ``setup_helpers`` file. + Building with cppimport ======================== @@ -33,8 +232,8 @@ extension module can be created with just a few lines of code: .. code-block:: cmake - cmake_minimum_required(VERSION 2.8.12) - project(example) + cmake_minimum_required(VERSION 3.4...3.18) + project(example LANGUAGES CXX) add_subdirectory(pybind11) pybind11_add_module(example example.cpp) @@ -50,6 +249,11 @@ PyPI integration, can be found in the [cmake_example]_ repository. .. [cmake_example] https://github.com/pybind/cmake_example +.. versionchanged:: 2.6 + CMake 3.4+ is required. + +Further information can be found at :doc:`cmake/index`. + pybind11_add_module ------------------- @@ -59,7 +263,7 @@ function with the following signature: .. code-block:: cmake pybind11_add_module(<name> [MODULE | SHARED] [EXCLUDE_FROM_ALL] - [NO_EXTRAS] [SYSTEM] [THIN_LTO] source1 [source2 ...]) + [NO_EXTRAS] [THIN_LTO] [OPT_SIZE] source1 [source2 ...]) This function behaves very much like CMake's builtin ``add_library`` (in fact, it's a wrapper function around that command). It will add a library target @@ -86,53 +290,68 @@ latter optimizations are never applied in ``Debug`` mode. If ``NO_EXTRAS`` is given, they will always be disabled, even in ``Release`` mode. However, this will result in code bloat and is generally not recommended. -By default, pybind11 and Python headers will be included with ``-I``. In order -to include pybind11 as system library, e.g. to avoid warnings in downstream -code with warn-levels outside of pybind11's scope, set the option ``SYSTEM``. - As stated above, LTO is enabled by default. Some newer compilers also support different flavors of LTO such as `ThinLTO`_. Setting ``THIN_LTO`` will cause the function to prefer this flavor if available. The function falls back to -regular LTO if ``-flto=thin`` is not available. +regular LTO if ``-flto=thin`` is not available. If +``CMAKE_INTERPROCEDURAL_OPTIMIZATION`` is set (either ``ON`` or ``OFF``), then +that will be respected instead of the built-in flag search. + +.. note:: + + If you want to set the property form on targets or the + ``CMAKE_INTERPROCEDURAL_OPTIMIZATION_<CONFIG>`` versions of this, you should + still use ``set(CMAKE_INTERPROCEDURAL_OPTIMIZATION OFF)`` (otherwise a + no-op) to disable pybind11's ipo flags. + +The ``OPT_SIZE`` flag enables size-based optimization equivalent to the +standard ``/Os`` or ``-Os`` compiler flags and the ``MinSizeRel`` build type, +which avoid optimizations that that can substantially increase the size of the +resulting binary. This flag is particularly useful in projects that are split +into performance-critical parts and associated bindings. In this case, we can +compile the project in release mode (and hence, optimize performance globally), +and specify ``OPT_SIZE`` for the binding target, where size might be the main +concern as performance is often less critical here. A ~25% size reduction has +been observed in practice. This flag only changes the optimization behavior at +a per-target level and takes precedence over the global CMake build type +(``Release``, ``RelWithDebInfo``) except for ``Debug`` builds, where +optimizations remain disabled. .. _ThinLTO: http://clang.llvm.org/docs/ThinLTO.html Configuration variables ----------------------- -By default, pybind11 will compile modules with the C++14 standard, if available -on the target compiler, falling back to C++11 if C++14 support is not -available. Note, however, that this default is subject to change: future -pybind11 releases are expected to migrate to newer C++ standards as they become -available. To override this, the standard flag can be given explicitly in -``PYBIND11_CPP_STANDARD``: +By default, pybind11 will compile modules with the compiler default or the +minimum standard required by pybind11, whichever is higher. You can set the +standard explicitly with +`CMAKE_CXX_STANDARD <https://cmake.org/cmake/help/latest/variable/CMAKE_CXX_STANDARD.html>`_: .. code-block:: cmake - # Use just one of these: - # GCC/clang: - set(PYBIND11_CPP_STANDARD -std=c++11) - set(PYBIND11_CPP_STANDARD -std=c++14) - set(PYBIND11_CPP_STANDARD -std=c++1z) # Experimental C++17 support - # MSVC: - set(PYBIND11_CPP_STANDARD /std:c++14) - set(PYBIND11_CPP_STANDARD /std:c++latest) # Enables some MSVC C++17 features + set(CMAKE_CXX_STANDARD 14 CACHE STRING "C++ version selection") # or 11, 14, 17, 20 + set(CMAKE_CXX_STANDARD_REQUIRED ON) # optional, ensure standard is supported + set(CMAKE_CXX_EXTENSIONS OFF) # optional, keep compiler extensionsn off - add_subdirectory(pybind11) # or find_package(pybind11) +The variables can also be set when calling CMake from the command line using +the ``-D<variable>=<value>`` flag. You can also manually set ``CXX_STANDARD`` +on a target or use ``target_compile_features`` on your targets - anything that +CMake supports. -Note that this and all other configuration variables must be set **before** the -call to ``add_subdirectory`` or ``find_package``. The variables can also be set -when calling CMake from the command line using the ``-D<variable>=<value>`` flag. - -The target Python version can be selected by setting ``PYBIND11_PYTHON_VERSION`` -or an exact Python installation can be specified with ``PYTHON_EXECUTABLE``. -For example: +Classic Python support: The target Python version can be selected by setting +``PYBIND11_PYTHON_VERSION`` or an exact Python installation can be specified +with ``PYTHON_EXECUTABLE``. For example: .. code-block:: bash cmake -DPYBIND11_PYTHON_VERSION=3.6 .. - # or - cmake -DPYTHON_EXECUTABLE=path/to/python .. + + # Another method: + cmake -DPYTHON_EXECUTABLE=/path/to/python .. + + # This often is a good way to get the current Python, works in environments: + cmake -DPYTHON_EXECUTABLE=$(python3 -c "import sys; print(sys.executable)") .. + find_package vs. add_subdirectory --------------------------------- @@ -143,8 +362,8 @@ See the `Config file`_ docstring for details of relevant CMake variables. .. code-block:: cmake - cmake_minimum_required(VERSION 2.8.12) - project(example) + cmake_minimum_required(VERSION 3.4...3.18) + project(example LANGUAGES CXX) find_package(pybind11 REQUIRED) pybind11_add_module(example example.cpp) @@ -155,12 +374,19 @@ the pybind11 repository : .. code-block:: bash + # Classic CMake cd pybind11 mkdir build cd build cmake .. make install + # CMake 3.15+ + cd pybind11 + cmake -S . -B build + cmake --build build -j 2 # Build on 2 cores + cmake --install build + Once detected, the aforementioned ``pybind11_add_module`` can be employed as before. The function usage and configuration variables are identical no matter if pybind11 is added as a subdirectory or found as an installed package. You @@ -169,41 +395,134 @@ can refer to the same [cmake_example]_ repository for a full sample project .. _Config file: https://github.com/pybind/pybind11/blob/master/tools/pybind11Config.cmake.in -Advanced: interface library target ----------------------------------- -When using a version of CMake greater than 3.0, pybind11 can additionally -be used as a special *interface library* . The target ``pybind11::module`` -is available with pybind11 headers, Python headers and libraries as needed, -and C++ compile definitions attached. This target is suitable for linking -to an independently constructed (through ``add_library``, not -``pybind11_add_module``) target in the consuming project. +.. _find-python-mode: + +FindPython mode +--------------- + +CMake 3.12+ (3.15+ recommended) added a new module called FindPython that had a +highly improved search algorithm and modern targets and tools. If you use +FindPython, pybind11 will detect this and use the existing targets instead: + +.. code-block:: cmake + + cmake_minumum_required(VERSION 3.15...3.18) + project(example LANGUAGES CXX) + + find_package(Python COMPONENTS Interpreter Development REQUIRED) + find_package(pybind11 CONFIG REQUIRED) + # or add_subdirectory(pybind11) + + pybind11_add_module(example example.cpp) + +You can also use the targets (as listed below) with FindPython. If you define +``PYBIND11_FINDPYTHON``, pybind11 will perform the FindPython step for you +(mostly useful when building pybind11's own tests, or as a way to change search +algorithms from the CMake invocation, with ``-DPYBIND11_FINDPYTHON=ON``. + +.. warning:: + + If you use FindPython2 and FindPython3 to dual-target Python, use the + individual targets listed below, and avoid targets that directly include + Python parts. + +There are `many ways to hint or force a discovery of a specific Python +installation <https://cmake.org/cmake/help/latest/module/FindPython.html>`_), +setting ``Python_ROOT_DIR`` may be the most common one (though with +virtualenv/venv support, and Conda support, this tends to find the correct +Python version more often than the old system did). + +.. versionadded:: 2.6 + +Advanced: interface library targets +----------------------------------- + +Pybind11 supports modern CMake usage patterns with a set of interface targets, +available in all modes. The targets provided are: + + ``pybind11::headers`` + Just the pybind11 headers and minimum compile requirements + + ``pybind11::python2_no_register`` + Quiets the warning/error when mixing C++14 or higher and Python 2 + + ``pybind11::pybind11`` + Python headers + ``pybind11::headers`` + ``pybind11::python2_no_register`` (Python 2 only) + + ``pybind11::python_link_helper`` + Just the "linking" part of pybind11:module + + ``pybind11::module`` + Everything for extension modules - ``pybind11::pybind11`` + ``Python::Module`` (FindPython CMake 3.15+) or ``pybind11::python_link_helper`` + + ``pybind11::embed`` + Everything for embedding the Python interpreter - ``pybind11::pybind11`` + ``Python::Embed`` (FindPython) or Python libs + + ``pybind11::lto`` / ``pybind11::thin_lto`` + An alternative to `INTERPROCEDURAL_OPTIMIZATION` for adding link-time optimization. + + ``pybind11::windows_extras`` + ``/bigobj`` and ``/mp`` for MSVC. + + ``pybind11::opt_size`` + ``/Os`` for MSVC, ``-Os`` for other compilers. Does nothing for debug builds. + +Two helper functions are also provided: + + ``pybind11_strip(target)`` + Strips a target (uses ``CMAKE_STRIP`` after the target is built) + + ``pybind11_extension(target)`` + Sets the correct extension (with SOABI) for a target. + +You can use these targets to build complex applications. For example, the +``add_python_module`` function is identical to: .. code-block:: cmake - cmake_minimum_required(VERSION 3.0) - project(example) + cmake_minimum_required(VERSION 3.4) + project(example LANGUAGES CXX) find_package(pybind11 REQUIRED) # or add_subdirectory(pybind11) add_library(example MODULE main.cpp) - target_link_libraries(example PRIVATE pybind11::module) - set_target_properties(example PROPERTIES PREFIX "${PYTHON_MODULE_PREFIX}" - SUFFIX "${PYTHON_MODULE_EXTENSION}") + + target_link_libraries(example PRIVATE pybind11::module pybind11::lto pybind11::windows_extras) + + pybind11_extension(example) + pybind11_strip(example) + + set_target_properties(example PROPERTIES CXX_VISIBILITY_PRESET "hidden" + CUDA_VISIBILITY_PRESET "hidden") + +Instead of setting properties, you can set ``CMAKE_*`` variables to initialize these correctly. .. warning:: Since pybind11 is a metatemplate library, it is crucial that certain compiler flags are provided to ensure high quality code generation. In contrast to the ``pybind11_add_module()`` command, the CMake interface - library only provides the *minimal* set of parameters to ensure that the - code using pybind11 compiles, but it does **not** pass these extra compiler - flags (i.e. this is up to you). + provides a *composable* set of targets to ensure that you retain flexibility. + It can be expecially important to provide or set these properties; the + :ref:`FAQ <faq:symhidden>` contains an explanation on why these are needed. + +.. versionadded:: 2.6 - These include Link Time Optimization (``-flto`` on GCC/Clang/ICPC, ``/GL`` - and ``/LTCG`` on Visual Studio) and .OBJ files with many sections on Visual - Studio (``/bigobj``). The :ref:`FAQ <faq:symhidden>` contains an - explanation on why these are needed. +.. _nopython-mode: + +Advanced: NOPYTHON mode +----------------------- + +If you want complete control, you can set ``PYBIND11_NOPYTHON`` to completely +disable Python integration (this also happens if you run ``FindPython2`` and +``FindPython3`` without running ``FindPython``). This gives you complete +freedom to integrate into an existing system (like `Scikit-Build's +<https://scikit-build.readthedocs.io>`_ ``PythonExtensions``). +``pybind11_add_module`` and ``pybind11_extension`` will be unavailable, and the +targets will be missing any Python specific behavior. + +.. versionadded:: 2.6 Embedding the Python interpreter -------------------------------- @@ -217,8 +536,8 @@ information about usage in C++, see :doc:`/advanced/embedding`. .. code-block:: cmake - cmake_minimum_required(VERSION 3.0) - project(example) + cmake_minimum_required(VERSION 3.4...3.18) + project(example LANGUAGES CXX) find_package(pybind11 REQUIRED) # or add_subdirectory(pybind11) @@ -255,7 +574,7 @@ Besides, the ``--extension-suffix`` option may or may not be available, dependin on the distribution; in the latter case, the module extension can be manually set to ``.so``. -On Mac OS: the build command is almost the same but it also requires passing +On macOS: the build command is almost the same but it also requires passing the ``-undefined dynamic_lookup`` flag so as to ignore missing symbols when building the module: @@ -279,6 +598,13 @@ build system that works on all platforms including Windows. of possibly importing a second Python library into a process that already contains one (which will lead to a segfault). + +Building with Bazel +=================== + +You can build with the Bazel build system using the `pybind11_bazel +<https://github.com/pybind/pybind11_bazel>`_ repository. + Generating binding code automatically ===================================== @@ -287,3 +613,18 @@ code by introspecting existing C++ codebases using LLVM/Clang. See the [binder]_ documentation for details. .. [binder] http://cppbinder.readthedocs.io/en/latest/about.html + +[AutoWIG]_ is a Python library that wraps automatically compiled libraries into +high-level languages. It parses C++ code using LLVM/Clang technologies and +generates the wrappers using the Mako templating engine. The approach is automatic, +extensible, and applies to very complex C++ libraries, composed of thousands of +classes or incorporating modern meta-programming constructs. + +.. [AutoWIG] https://github.com/StatisKit/AutoWIG + +[robotpy-build]_ is a is a pure python, cross platform build tool that aims to +simplify creation of python wheels for pybind11 projects, and provide +cross-project dependency management. Additionally, it is able to autogenerate +customizable pybind11-based wrappers by parsing C++ header files. + +.. [robotpy-build] https://robotpy-build.readthedocs.io |