gt<> validator sets incorrect from_value in parameter descriptor

[ottojo]

The ranges in the parameter descriptor are inclusive (https://github.com/ros2/rcl_interfaces/blob/rolling/rcl_interfaces/msg/FloatingPointRange.msg#L3), but currently the gt<> validator sets the lower limit to the specified value (instead of the next larger value):

generate_parameter_library/generate_parameter_library_py/generate_parameter_library_py/jinja_templates/cpp/declare_parameter

Line 17 in 13a1043

descriptor.floating_point_range.at({{loop.index0}}).from_value = {{validation.arguments[0]}};

This results in inconsistent behavior between parameter descriptor and parameter validation:

jonas@ade $ ros2 param describe /example_node background.gt_zero_float                            
Parameter name: background.gt_zero_float
  Type: double
  Description: Parameter with default value 1.0 and gt<>: 0.0 validation
  Constraints:
    Min value: 0.0
    Max value: 1.7976931348623157e+308
jonas@ade $ ros2 param set /example_node background.gt_zero_float 0.0 
Setting parameter failed: Parameter 'background.gt_zero_float' with the value '0' must be greater than '0'

[christophfroehlich]

I don't understand this tbh. From the link, the floating_point_range is inclusive, but why is your ros2 param set command failing then?

Setting gt an gt_eq to the same value is obviously not correct

generate_parameter_library/generate_parameter_library_py/generate_parameter_library_py/jinja_templates/cpp/declare_parameter

Lines 15 to 22 in c9bd79f

	{%- elif ("lower" in validation.function_name or "gt" == validation.function_base_name or "gt_eq" == validation.function_base_name) and validation.arguments|length == 1 %}
	descriptor.floating_point_range.resize({{loop.index}});
	descriptor.floating_point_range.at({{loop.index0}}).from_value = {{validation.arguments[0]}};
	descriptor.floating_point_range.at({{loop.index0}}).to_value = std::numeric_limits<double>::max();
	{%- elif ("upper" in validation.function_name or "lt" == validation.function_base_name or "lt_eq" == validation.function_base_name) and validation.arguments|length == 1 %}
	descriptor.floating_point_range.resize({{loop.index}});
	descriptor.floating_point_range.at({{loop.index0}}).from_value = std::numeric_limits<double>::lowest();
	descriptor.floating_point_range.at({{loop.index0}}).to_value = {{validation.arguments[0]}};

[ottojo]

I think i made a mistake and meant to write "The ranges in the parameter descriptor are inclusive" in the first sentence of the issue. I will edit it correspondingly.

As far as i can tell the ros2 param set failing is because the validator uses the provided argument directly, instead of the ROS parameter descriptor. ( I specified the parameter should be greater than zero, so setting it to zero fails).

The only thing actually wrong is the output of ros2 param describe, which shows the contents of the parameter descriptor. (And incorrectly suggests that setting the parameter to zero is allowed).

[christophfroehlich]

With #336 I had a closer look. The validators called from ros2 param set always were fine because the use directly the validators from rsl.
As you mentioned, the ros2 param describe from rcl_interfaces::msg::ParameterDescriptor is not aware of exclusive bounds.
#339 could fix this.

[christophfroehlich]

@ottojo do you mind having a look at the PR and leave a review there?