FindPython3

Find Python 3 interpreter, compiler and development environment (include directories and libraries).

The following components are supported:

  • Interpreter: search for Python 3 interpreter

  • Compiler: search for Python 3 compiler. Only offered by IronPython.

  • Development: search for development artifacts (include directories and libraries)

  • NumPy: search for NumPy include directories.

If no COMPONENTS are specified, Interpreter is assumed.

To ensure consistent versions between components Interpreter, Compiler, Development and NumPy, specify all components at the same time:

find_package (Python3 COMPONENTS Interpreter Development)

This module looks only for version 3 of Python. This module can be used concurrently with FindPython2 module to use both Python versions.

The FindPython module can be used if Python version does not matter for you.

Note

If components Interpreter and Development are both specified, this module search only for interpreter with same platform architecture as the one defined by CMake configuration. This contraint does not apply if only Interpreter component is specified.

Imported Targets

This module defines the following Imported Targets (when CMAKE_ROLE is PROJECT):

Python3::Interpreter

Python 3 interpreter. Target defined if component Interpreter is found.

Python3::Compiler

Python 3 compiler. Target defined if component Compiler is found.

Python3::Python

Python 3 library for Python embedding. Target defined if component Development is found.

Python3::Module

Python 3 library for Python module. Target defined if component Development is found.

Python3::NumPy

NumPy library for Python 3. Target defined if component NumPy is found.

Result Variables

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

Python3_FOUND

System has the Python 3 requested components.

Python3_Interpreter_FOUND

System has the Python 3 interpreter.

Python3_EXECUTABLE

Path to the Python 3 interpreter.

Python3_INTERPRETER_ID
A short string unique to the interpreter. Possible values include:

  • Python

  • ActivePython

  • Anaconda

  • Canopy

  • IronPython

Python3_STDLIB

Standard platform independent installation directory.

Information returned by distutils.sysconfig.get_python_lib(plat_specific=False,standard_lib=True).

Python3_STDARCH

Standard platform dependent installation directory.

Information returned by distutils.sysconfig.get_python_lib(plat_specific=True,standard_lib=True).

Python3_SITELIB

Third-party platform independent installation directory.

Information returned by distutils.sysconfig.get_python_lib(plat_specific=False,standard_lib=False).

Python3_SITEARCH

Third-party platform dependent installation directory.

Information returned by distutils.sysconfig.get_python_lib(plat_specific=True,standard_lib=False).

Python3_Compiler_FOUND

System has the Python 3 compiler.

Python3_COMPILER

Path to the Python 3 compiler. Only offered by IronPython.

Python3_COMPILER_ID
A short string unique to the compiler. Possible values include:

  • IronPython

Python3_Development_FOUND

System has the Python 3 development artifacts.

Python3_INCLUDE_DIRS

The Python 3 include directories.

Python3_LIBRARIES

The Python 3 libraries.

Python3_LIBRARY_DIRS

The Python 3 library directories.

Python3_RUNTIME_LIBRARY_DIRS

The Python 3 runtime library directories.

Python3_VERSION

Python 3 version.

Python3_VERSION_MAJOR

Python 3 major version.

Python3_VERSION_MINOR

Python 3 minor version.

Python3_VERSION_PATCH

Python 3 patch version.

Python3_NumPy_FOUND

System has the NumPy.

Python3_NumPy_INCLUDE_DIRS

The NumPy include directries.

Python3_NumPy_VERSION

The NumPy version.

Hints

Python3_ROOT_DIR

Define the root directory of a Python 3 installation.

Python3_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.

Python3_FIND_ABI

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

Note

If Python3_FIND_ABI is not defined, any ABI will be searched.

The Python3_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 posibilties (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 (Python3_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 (Python3_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 Python3_FIND_ABI is defined, Python distributions from python.org will be found only if value for each flag is OFF or ANY.

Python3_FIND_STRATEGY

This variable defines how lookup will be done. The Python3_FIND_STRATEGY variable can be set to empty or 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.

Python3_FIND_REGISTRY

On Windows the Python3_FIND_REGISTRY variable determine the order of preference between registry and environment variables. The Python3_FIND_REGISTRY variable can be set to empty or 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.

Python3_FIND_FRAMEWORK

On macOS the Python3_FIND_FRAMEWORK variable determine the order of preference between Apple-style and unix-style package components. This variable can be set to empty or take same values as CMAKE_FIND_FRAMEWORK variable.

Note

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

If Python3_FIND_FRAMEWORK is not defined, CMAKE_FIND_FRAMEWORK variable will be used, if any.

Python3_FIND_VIRTUALENV

This variable defines the handling of virtual environments. It is meaningfull only when a virtual environment is active (i.e. the activate script has been evaluated). In this case, it takes precedence over Python3_FIND_REGISTRY and CMAKE_FIND_FRAMEWORK variables. The Python3_FIND_VIRTUALENV variable can be set to empty or 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. In this case, variable Python3_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.

Note

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

Artifacts Specification

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

Python3_EXECUTABLE

The path to the interpreter.

Python3_COMPILER

The path to the compiler.

Python3_LIBRARY

The path to the library. It will be used to compute the variables Python3_LIBRARIES, Python3_LIBRAY_DIRS and Python3_RUNTIME_LIBRARY_DIRS.

Python3_INCLUDE_DIR

The path to the directory of the Python headers. It will be used to compute the variable Python3_INCLUDE_DIRS.

Python3_NumPy_INCLUDE_DIR

The path to the directory of the NumPy headers. It will be used to compute the variable Python3_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 responsability to ensure the consistency of the various artifacts.

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 Python3::Python or, when library type is MODULE, to target Python3::Module and takes care of Python module naming rules:

Python3_add_library (my_module MODULE src1.cpp)

If library type is not specified, MODULE is assumed.