FindPython — CMake 3.29.3 Documentation

# FindPython

New in version 3.12.

Find Python interpreter, compiler and development environment (include directories and libraries).

New in version 3.19: When a version is requested, it can be specified as a simple value or as a range. For a detailed description of version range usage and capabilities, refer to the `find_package()` command.

The following components are supported:

- `Interpreter`: search for Python interpreter.

- `Compiler`: search for Python compiler. Only offered by IronPython.

- `Development`: search for development artifacts (include directories and libraries).

  New in version 3.18: This component includes two sub-components which can be specified independently:

  - `Development.Module`: search for artifacts for Python module developments.

  - `Development.Embed`: search for artifacts for Python embedding developments.

  New in version 3.26:

  - `Development.SABIModule`: search for artifacts for Python module developments using the Stable Application Binary Interface. This component is available only for version `3.2` and upper.

- `NumPy`: search for NumPy include directories.

New in version 3.14: Added the `NumPy` component.

If no `COMPONENTS` are specified, `Interpreter` is assumed.

If component `Development` is specified, it implies sub-components `Development.Module` and `Development.Embed`.

To ensure consistent versions between components `Interpreter`, `Compiler`, `Development` (or one of its sub-components) and `NumPy`, specify all components at the same time:

    find_package (Python COMPONENTS Interpreter Development)

This module looks preferably for version 3 of Python. If not found, version 2 is searched. To manage concurrent versions 3 and 2 of Python, use `FindPython3` and `FindPython2` modules rather than this one.

Note

If components `Interpreter` and `Development` (or one of its sub-components) are both specified, this module search only for interpreter with same platform architecture as the one defined by CMake configuration. This constraint does not apply if only `Interpreter` component is specified.

## Imported Targets

This module defines the following Imported Targets:

Changed in version 3.14: Imported Targets are only created when `CMAKE_ROLE` is `PROJECT`.

`Python::Interpreter`

  Python interpreter. Target defined if component `Interpreter` is found.

`Python::Compiler`

  Python compiler. Target defined if component `Compiler` is found.

`Python::Module`

  New in version 3.15.

  Python library for Python module. Target defined if component `Development.Module` is found.

`Python::SABIModule`

  New in version 3.26.

  Python library for Python module using the Stable Application Binary Interface. Target defined if component `Development.SABIModule` is found.

`Python::Python`

  Python library for Python embedding. Target defined if component `Development.Embed` is found.

`Python::NumPy`

  New in version 3.14.

  NumPy Python library. Target defined if component `NumPy` is found.

## Result Variables

This module will set the following variables in your project (see Standard Variable Names):

`Python_FOUND`

  System has the Python requested components.

`Python_Interpreter_FOUND`

  System has the Python interpreter.

`Python_EXECUTABLE`

  Path to the Python interpreter.

`Python_INTERPRETER_ID`
  A short string unique to the interpreter. Possible values include:

    - Python

    - ActivePython

    - Anaconda

    - Canopy

    - IronPython

    - PyPy

`Python_STDLIB`

  Standard platform independent installation directory.

  Information returned by `sysconfig.get_path('stdlib')`.

`Python_STDARCH`

  Standard platform dependent installation directory.

  Information returned by `sysconfig.get_path('platstdlib')`.

`Python_SITELIB`

  Third-party platform independent installation directory.

  Information returned by `sysconfig.get_path('purelib')`.

`Python_SITEARCH`

  Third-party platform dependent installation directory.

  Information returned by `sysconfig.get_path('platlib')`.

`Python_SOABI`

  New in version 3.17.

  Extension suffix for modules.

  Information computed from `sysconfig.get_config_var('EXT_SUFFIX')` or `sysconfig.get_config_var('SOABI')` or `python3-config --extension-suffix`.

`Python_SOSABI`

  New in version 3.26.

  Extension suffix for modules using the Stable Application Binary Interface.

  Information computed from `importlib.machinery.EXTENSION_SUFFIXES` if the COMPONENT `Interpreter` was specified. Otherwise, the extension is `abi3` except for `Windows`, `MSYS` and `CYGWIN` for which this is an empty string.

`Python_Compiler_FOUND`

  System has the Python compiler.

`Python_COMPILER`

  Path to the Python compiler. Only offered by IronPython.

`Python_COMPILER_ID`
  A short string unique to the compiler. Possible values include:

    - IronPython

`Python_DOTNET_LAUNCHER`

  New in version 3.18.

  The `.Net` interpreter. Only used by `IronPython` implementation.

`Python_Development_FOUND`

  System has the Python development artifacts.

`Python_Development.Module_FOUND`

  New in version 3.18.

  System has the Python development artifacts for Python module.

`Python_Development.SABIModule_FOUND`

  New in version 3.26.

  System has the Python development artifacts for Python module using the Stable Application Binary Interface.

`Python_Development.Embed_FOUND`

  New in version 3.18.

  System has the Python development artifacts for Python embedding.

`Python_INCLUDE_DIRS`

> The Python include directories.

`Python_LINK_OPTIONS`

  New in version 3.19.

  The Python link options. Some configurations require specific link options for a correct build and execution.

`Python_LIBRARIES`

  The Python libraries.

`Python_LIBRARY_DIRS`

  The Python library directories.

`Python_RUNTIME_LIBRARY_DIRS`

  The Python runtime library directories.

`Python_SABI_LIBRARIES`

  New in version 3.26.

  The Python libraries for the Stable Application Binary Interface.

`Python_SABI_LIBRARY_DIRS`

  New in version 3.26.

  The Python `SABI` library directories.

`Python_RUNTIME_SABI_LIBRARY_DIRS`

  New in version 3.26.

  The Python runtime `SABI` library directories.

`Python_VERSION`

  Python version.

`Python_VERSION_MAJOR`

  Python major version.

`Python_VERSION_MINOR`

  Python minor version.

`Python_VERSION_PATCH`

  Python patch version.

`Python_PyPy_VERSION`

  New in version 3.18.

  Python PyPy version.

`Python_NumPy_FOUND`

  New in version 3.14.

  System has the NumPy.

`Python_NumPy_INCLUDE_DIRS`

  New in version 3.14.

  The NumPy include directories.

`Python_NumPy_VERSION`

  New in version 3.14.

  The NumPy version.

## Hints

`Python_ROOT_DIR`

  Define the root directory of a Python installation.

`Python_USE_STATIC_LIBS`

  - If not defined, search for shared libraries and static libraries in that order.

  - If set to TRUE, search only for static libraries.

  - If set to FALSE, search only for shared libraries.

  Note

  This hint will be ignored on `Windows` because static libraries are not available on this platform.

`Python_FIND_ABI`

  New in version 3.16.

  This variable defines which ABIs, as defined in PEP 3149, should be searched.

  Note

  This hint will be honored only when searched for `Python` version 3.

  Note

  If `Python_FIND_ABI` is not defined, any ABI will be searched.

  The `Python_FIND_ABI` variable is a 3-tuple specifying, in that order, `pydebug` (`d`), `pymalloc` (`m`) and `unicode` (`u`) flags. Each element can be set to one of the following:

  - `ON`: Corresponding flag is selected.

  - `OFF`: Corresponding flag is not selected.

  - `ANY`: The two possibilities (`ON` and `OFF`) will be searched.

  From this 3-tuple, various ABIs will be searched starting from the most specialized to the most general. Moreover, `debug` versions will be searched after `non-debug` ones.

  For example, if we have:

      set (Python_FIND_ABI "ON" "ANY" "ANY")

  The following flags combinations will be appended, in that order, to the artifact names: `dmu`, `dm`, `du`, and `d`.

  And to search any possible ABIs:

      set (Python_FIND_ABI "ANY" "ANY" "ANY")

  The following combinations, in that order, will be used: `mu`, `m`, `u`, `<empty>`, `dmu`, `dm`, `du` and `d`.

  Note

  This hint is useful only on `POSIX` systems. So, on `Windows` systems, when `Python_FIND_ABI` is defined, `Python` distributions from python.org will be found only if value for each flag is `OFF` or `ANY`.

`Python_FIND_STRATEGY`

  New in version 3.15.

  This variable defines how lookup will be done. The `Python_FIND_STRATEGY` variable can be set to one of the following:

  - `VERSION`: Try to find the most recent version in all specified locations. This is the default if policy `CMP0094` is undefined or set to `OLD`.

  - `LOCATION`: Stops lookup as soon as a version satisfying version constraints is founded. This is the default if policy `CMP0094` is set to `NEW`.

  See also `Python_FIND_UNVERSIONED_NAMES`.

`Python_FIND_REGISTRY`

  New in version 3.13.

  On Windows the `Python_FIND_REGISTRY` variable determine the order of preference between registry and environment variables. the `Python_FIND_REGISTRY` variable can be set to one of the following:

  - `FIRST`: Try to use registry before environment variables. This is the default.

  - `LAST`: Try to use registry after environment variables.

  - `NEVER`: Never try to use registry.

`Python_FIND_FRAMEWORK`

  New in version 3.15.

  On macOS the `Python_FIND_FRAMEWORK` variable determine the order of preference between Apple-style and unix-style package components. This variable can take same values as `CMAKE_FIND_FRAMEWORK` variable.

  Note

  Value `ONLY` is not supported so `FIRST` will be used instead.

  If `Python_FIND_FRAMEWORK` is not defined, `CMAKE_FIND_FRAMEWORK` variable will be used, if any.

`Python_FIND_VIRTUALENV`

  New in version 3.15.

  This variable defines the handling of virtual environments managed by `virtualenv` or `conda`. It is meaningful only when a virtual environment is active (i.e. the `activate` script has been evaluated). In this case, it takes precedence over `Python_FIND_REGISTRY` and `CMAKE_FIND_FRAMEWORK` variables. The `Python_FIND_VIRTUALENV` variable can be set to one of the following:

  - `FIRST`: The virtual environment is used before any other standard paths to look-up for the interpreter. This is the default.

  - `ONLY`: Only the virtual environment is used to look-up for the interpreter.

  - `STANDARD`: The virtual environment is not used to look-up for the interpreter but environment variable `PATH` is always considered. In this case, variable `Python_FIND_REGISTRY` (Windows) or `CMAKE_FIND_FRAMEWORK` (macOS) can be set with value `LAST` or `NEVER` to select preferably the interpreter from the virtual environment.

  New in version 3.17: Added support for `conda` environments.

  Note

  If the component `Development` is requested, it is strongly recommended to also include the component `Interpreter` to get expected result.

`Python_FIND_IMPLEMENTATIONS`

  New in version 3.18.

  This variable defines, in an ordered list, the different implementations which will be searched. The `Python_FIND_IMPLEMENTATIONS` variable can hold the following values:

  - `CPython`: this is the standard implementation. Various products, like `Anaconda` or `ActivePython`, rely on this implementation.

  - `IronPython`: This implementation use the `CSharp` language for `.NET Framework` on top of the Dynamic Language Runtime (`DLR`). See IronPython.

  - `PyPy`: This implementation use `RPython` language and `RPython translation toolchain` to produce the python interpreter. See PyPy.

  The default value is:

  - Windows platform: `CPython`, `IronPython`

  - Other platforms: `CPython`

  Note

  This hint has the lowest priority of all hints, so even if, for example, you specify `IronPython` first and `CPython` in second, a python product based on `CPython` can be selected because, for example with `Python_FIND_STRATEGY=LOCATION`, each location will be search first for `IronPython` and second for `CPython`.

  Note

  When `IronPython` is specified, on platforms other than `Windows`, the `.Net` interpreter (i.e. `mono` command) is expected to be available through the `PATH` variable.

`Python_FIND_UNVERSIONED_NAMES`

  New in version 3.20.

  This variable defines how the generic names will be searched. Currently, it only applies to the generic names of the interpreter, namely, `python3` or `python2` and `python`. The `Python_FIND_UNVERSIONED_NAMES` variable can be set to one of the following values:

  - `FIRST`: The generic names are searched before the more specialized ones (such as `python2.5` for example).

  - `LAST`: The generic names are searched after the more specialized ones. This is the default.

  - `NEVER`: The generic name are not searched at all.

  See also `Python_FIND_STRATEGY`.

## Artifacts Specification

New in version 3.16.

To solve special cases, it is possible to specify directly the artifacts by setting the following variables:

`Python_EXECUTABLE`

  The path to the interpreter.

`Python_COMPILER`

  The path to the compiler.

`Python_DOTNET_LAUNCHER`

  New in version 3.18.

  The `.Net` interpreter. Only used by `IronPython` implementation.

`Python_LIBRARY`

  The path to the library. It will be used to compute the variables `Python_LIBRARIES`, `Python_LIBRARY_DIRS` and `Python_RUNTIME_LIBRARY_DIRS`.

`Python_SABI_LIBRARY`

  New in version 3.26.

  The path to the library for Stable Application Binary Interface. It will be used to compute the variables `Python_SABI_LIBRARIES`, `Python_SABI_LIBRARY_DIRS` and `Python_RUNTIME_SABI_LIBRARY_DIRS`.

`Python_INCLUDE_DIR`

  The path to the directory of the `Python` headers. It will be used to compute the variable `Python_INCLUDE_DIRS`.

`Python_NumPy_INCLUDE_DIR`

  The path to the directory of the `NumPy` headers. It will be used to compute the variable `Python_NumPy_INCLUDE_DIRS`.

Note

All paths must be absolute. Any artifact specified with a relative path will be ignored.

Note

When an artifact is specified, all `HINTS` will be ignored and no search will be performed for this artifact.

If more than one artifact is specified, it is the user's responsibility to ensure the consistency of the various artifacts.

By default, this module supports multiple calls in different directories of a project with different version/component requirements while providing correct and consistent results for each call. To support this behavior, CMake cache is not used in the traditional way which can be problematic for interactive specification. So, to enable also interactive specification, module behavior can be controlled with the following variable:

`Python_ARTIFACTS_INTERACTIVE`

  New in version 3.18.

  Selects the behavior of the module. This is a boolean variable:

  - If set to `TRUE`: Create CMake cache entries for the above artifact specification variables so that users can edit them interactively. This disables support for multiple version/component requirements.

  - If set to `FALSE` or undefined: Enable multiple version/component requirements.

## Commands

This module defines the command `Python_add_library` (when `CMAKE_ROLE` is `PROJECT`), which has the same semantics as `add_library()` and adds a dependency to target `Python::Python` or, when library type is `MODULE`, to target `Python::Module` or `Python::SABIModule` (when `USE_SABI` option is specified) and takes care of Python module naming rules:

    Python_add_library (<name> [STATIC | SHARED | MODULE [USE_SABI <version>] [WITH_SOABI]]
                        <source1> [<source2> ...])

If the library type is not specified, `MODULE` is assumed.

New in version 3.17: For `MODULE` library type, if option `WITH_SOABI` is specified, the module suffix will include the `Python_SOABI` value, if any.

New in version 3.26: For `MODULE` type, if the option `USE_SABI` is specified, the preprocessor definition `Py_LIMITED_API` will be specified, as `PRIVATE`, for the target `<name>` with the value computed from `<version>` argument. The expected format for `<version>` is `major[.minor]`, where each component is a numeric value. If `minor` component is specified, the version should be, at least, `3.2` which is the version where the Stable Application Binary Interface was introduced. Specifying only major version `3` is equivalent to `3.2`.

When option `WITH_SOABI` is also specified, the module suffix will include the `Python_SOSABI` value, if any.