A reference to a parameter for use in DSL fields.

Instead of providing a literal unit value in the DSL, users can reference a parameter that will be resolved at runtime. This enables runtime-adjustable configuration for values that would otherwise be compile-time constants.

Usage

parameters do
  group :motion do
    param :max_effort, type: {:unit, :newton_meter}, default: ~u(10 newton_meter)
  end
end

topology do
  link :base do
    joint :shoulder do
      limit do
        effort(param([:motion, :max_effort]))
      end
    end
  end
end

The param/1 function creates a reference that:

• Is validated at compile-time to ensure the parameter exists
• Is resolved at robot startup to get the current parameter value
• Subscribes to parameter changes to keep the robot struct updated