launch_config_as_bool.py

# Copyright (c) 2025 Nishalan Govender
#
# 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.
 
import launch
from launch import LaunchContext
from launch.substitutions import LaunchConfiguration
from launch.utilities import perform_substitutions
 
 
class LaunchConfigAsBool(launch.Substitution):
    """
    Converts a LaunchConfiguration value into a normalized boolean string: 'true' or 'false'.
 
    Allows CLI arguments like 'True', 'true', '1', 'yes' and 'False', 'false', '0', 'no'.
    Returns a string 'true' or 'false' for use in PythonExpression and IfCondition contexts.
    """
 
    def __init__(self, name: str) -> None:
        super().__init__()
        self._config_config = LaunchConfiguration(name)
 
    def perform(self, context: LaunchContext) -> str:
        value = perform_substitutions(context, [self._config_config])
        if value.strip().lower() in ['true', '1', 'yes', 'on']:
            return 'True'
        return 'False'
 
    def describe(self) -> str:
        return f'LaunchConfigAsBool({self._config.describe()})'