[ros2param] ros2 param set does not work for array types

[sgvandijk]

Bug report

• Operating System:
  • Arch Linux 4.20.8-arch1-1-ARCH
• Installation type:
  • source
• Version or commit hash:
  • 66efd10
• DDS implementation:
  • Fast-RTPS

Steps to reproduce issue

rclpy:

• Create a node with a parameter of an array type, such as integer array:

import rclpy
from rclpy.parameter import Parameter


def main(args=None):
    rclpy.init(args=args)

    node = rclpy.create_node('param_array')
    node.set_parameters([Parameter("foo", Parameter.Type.INTEGER_ARRAY, [0, 0])])
    
    def timer_callback():
        node.get_logger().info('Value: {}, type: {}'.format(
            node.get_parameter("foo").value,
            type(node.get_parameter("foo").value)))

    timer = node.create_timer(1, timer_callback)
    rclpy.spin(node)

    node.destroy_node()
    rclpy.shutdown()


if __name__ == '__main__':
    main()

• Set parameter using ros2 param set:

ros2 param set /param_array foo "[1, 1]"

rclcpp:

• Create a node with a parameter of an array type, such as integer array:

std::vector<int64_t> foo;
get_parameter("foo", foo);

• Set parameter using ros2 param set

Expected behavior

Array parameter set successfully.

Actual behavior

rclpy:
No exception, but parameter is set to the raw string value:

[INFO] [param_array]: Value: [0, 0], type: <class 'list'>
[INFO] [param_array]: Value: [0, 0], type: <class 'list'>
# param set is run
[INFO] [param_array]: Value: [1, 1], type: <class 'str'>
[INFO] [param_array]: Value: [1, 1], type: <class 'str'>
[INFO] [param_array]: Value: [1, 1], type: <class 'str'>

rclcpp:
ParameterTypeException thrown:

terminate called after throwing an instance of 'rclcpp::ParameterTypeException'                                     
  what():  expected [integer_array] got [string]