INTERPRETER.md

Using rwloadsim as an interpreter

You can use rwloadsim as in interpreter using

#!/usr/bin/env rwloadsim

as the first lines of a script file that is given execute permission. As an example, if you create a file called echo.rwl with the following contents, put it in your PATH, and give it execute permission:

#!/usr/bin/env rwloadsim

# This is an implementation of the "echo" command
# using rwloadsim with an optional --commaseparate

$longoption:file-count=1 # Tell there is just this input rwl file
$longoption:quiet # Do not show the banner

integer commaseparate := 0;
$userswitch:commaseparate:"--commaseparate : Separate using comma"

while $# execute
  if $# = 1 then
    printline $1;
  else
    print $1 commaseparate ? "," : " ";
  end if;
  shift;
end while;

you have effectively implemented the echo command using rwloadsim, and it can used like this:

$ echo.rwl --commaseparate hello world
hello,world

Note that inclusion of the directives $longoption:file-count=1 and $longoption:quiet in echo.rwl imply both --quiet to not display the banner and --file-count=1 to make rwloadsim use all subsequent arguments as positional arguments made available as $1, etc. You can also ask for help text:

$ echo.rwl -H
RWP*Load Simulator user options from /path/to/bin/echo.rwl:

--commaseparate:
Separate using comma

Note that the script file must be named with the .rwl suffix for the $longoption directive to be effective.

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