[launch] add new concept for LaunchArgument #107
The idea behind the concept of
If the launch description is included by another launch description then the arguments would be part of that action, but if the launch description is "run" by
This is partially equivalent to the
It should take a name, optionally a default value, optionally documentation for the argument, and possibly other things commonly associated with command line arguments, like being a flag rather than a key-value option or with special validation logic (is it the right type or in the right range)? Initially it should always have a type of string, and it can be evaluated by the things consuming it.
The result (default value or user provided) would be stored in a