Comment by layer8

Another parsing step is the common case. Few parameters represent untyped strings where all characters and values are valid. For numbers as well, you often have a limited admissible range that you have to validate for. In the present case, you wouldn’t allow negative numbers, and maybe wouldn’t allow fractional numbers. Checking for a valid number isn’t inherently different from checking for a regex match. A number plus unit suffix is a straightforward regex.