Suppose I have a boolean argument foo

def generate_launch_description() -> launch.LaunchDescription:
    foo = LaunchConfiguration("foo")
    foo_arg = DeclareLaunchArgument("foo_arg", default_value="False")

First part of my question: let's say I have a node that takes in a string parameter. And I would like to set the value of the string parameter conditioned on the value of foo. How do I achieve this?

node = Node(
    package="mypkg",
    executable="mynode",
    output="screen",
    parameters=[{
        "my_string_param": # <...> value should depend on `foo`
    }]
)
ld.add_action(node)

Here is the second part of my question. What if, let's say, the value to my_string_param is the output of some function func(str) -> str, so the node block looks like:

node = Node(
    package="mypkg",
    executable="mynode",
    output="screen",
    parameters=[{
        "my_string_param": func(temp_str) # temp_str's value depends on `foo`
    }]
)
ld.add_action(node)

and I would like to set temp_str to be dependent on the truth value of foo. How do I achieve this?

Assume that the node itself is complex and there is no way to change how it behaves.

Node(
    package="my_pkg",
    executable="my_node",
    parameters=[{"my_string_param": "value if True"}],
    condition=IfCondition(your_boolean_arg)
    )
Node(
    package="my_pkg",
    executable="my_node",
    parameters=[{"my_string_param": "value if False"}],
    condition=UnlessCondition(your_boolean_arg)
    )