python_install_path.py

# Copyright 2022 Open Source Robotics Foundation, Inc.
# Licensed under the Apache License, Version 2.0

from pathlib import Path
import sysconfig


def get_python_install_path(name, vars_=()):
    """
    Get Python install paths matching Colcon's preferred scheme.

    See sysconfig.get_path for more info about the arguments.

    :param name: Name of the path type
    :param vars_: A dictionary of variables updating the values of
        sysconfig.get_config_vars()
    :rtype: Pathlib.Path
    """
    kwargs = {}
    kwargs['vars'] = dict(vars_)

    install_base = kwargs['vars'].get('base', sysconfig.get_config_var('base'))
    if install_base != sysconfig.get_config_var('base'):
        # If we are not actually installing to the default location, the
        # default path scheme may be inadequate. Check if we need to override.
        schemes = sysconfig.get_scheme_names()
        if 'deb_system' in schemes or 'osx_framework_library' in schemes:
            # Avoid deb_system because it requires using --install-layout deb
            # which ignores --prefix and hardcodes it to /usr
            kwargs['scheme'] = 'posix_prefix'
        elif 'rpm_prefix' in schemes:
            # The presence of the rpm_prefix scheme indicates that posix_prefix
            # has been patched to inject `local` into the installation
            # locations. The rpm_prefix scheme is a backup of what posix_prefix
            # was before it was patched.
            kwargs['scheme'] = 'rpm_prefix'

    return Path(sysconfig.get_path(name, **kwargs))