yaml parser raises an error "Sequence should be of same type" when meets .nan in list of doubles

[iquater]

ros2 launch raises an exception while parsing list with .nan value

• Operating System:
  • Ubuntu 18.04
• Installation type:
  • binaries
• Version or commit hash:
  • dashing
• DDS implementation:
  • Fast-RTPS
• Client library (if applicable):
  • rclcpp, rclpy

Steps to reproduce issue

Create python or cpp package:

import rclpy
from rclpy.node import Node


class TestNode(Node):
    def __init__(self):
        super().__init__("parameter_holder")

def main(args=None):
    rclpy.init(args=args)
    parameter_holder = TestNode()
    rclpy.spin(parameter_holder)
    parameter_holder.destroy_node()
    rclpy.shutdown()
    return 0

launch file:

from launch.launch_description import LaunchDescription
from launch_ros.actions import Node

def generate_launch_description():
    return LaunchDescription([
        Node(package='reprod',
             node_executable='param_holder',
             node_name='parameter_holder',
             output='screen',
             parameters=[
                 "/tmp/test.yaml"
             ])
    ])

configuration file

parameter_holder:
    ros__parameters:
        test_list: [1.0, 2.0]
        test_list2: [1.0, .nan]

Expected behavior

Yaml parser should treat .nan as valid double (or float) value.

Actual behavior

Yaml parser treats .nan as string and throws exception:

RuntimeError: Failed to parse yaml params file '/tmp/test.yaml': Sequence should be of same type. Value type 'string' do not belong at line_num 4

[dirk-thomas]

Loosely related to ros2/rosidl#351.

[ivanpauno]

@iquater Thanks for opening the issue. This is not currently supported, but it's a desired feature.
A PR adding support to special floating point values is more than welcomed.