python_launch_description_source.py

# Copyright 2018 Open Source Robotics Foundation, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""Module for the PythonLaunchDescriptionSource class."""

from .python_launch_file_utilities import get_launch_description_from_python_launch_file
from ..launch_description_source import LaunchDescriptionSource
from ..some_substitutions_type import SomeSubstitutionsType


class PythonLaunchDescriptionSource(LaunchDescriptionSource):
    """Encapsulation of a Python launch file, which can be loaded during launch."""

    def __init__(
        self,
        launch_file_path: SomeSubstitutionsType,
    ) -> None:
        """
        Create a PythonLaunchDescriptionSource.

        The given file path should be to a ``.launch.py`` style file.
        The path should probably be absolute, since the current working
        directory will be wherever the launch file was run from, which might
        change depending on the situation.
        The path can be made up of Substitution instances which are expanded
        when :py:meth:`get_launch_description()` is called.

        See also :py:func:`get_launch_description_from_python_launch_file`.

        :param launch_file_path: the path to the launch file
        """
        super().__init__(
            None,
            launch_file_path,
            'interpreted python launch file'
        )

    def _get_launch_description(self, location):
        """Get the LaunchDescription from location."""
        return get_launch_description_from_python_launch_file(location)