Bash can also employ a kind of function pointer, which can greatly simplify command-line argument parsing. Consider the following simplified example:

    ARG_ARCH="amd64"

    ARGUMENTS+=(
      "ARG_ARCH,a,arch,Target operating system architecture (${ARG_ARCH})"
      "log=utile_log,V,verbose,Log messages while processing"
    )

    utile_log() { echo "$1" }

    noop()      { return 1 }

    log=noop

By creating a comma-delimited list of command-line arguments, the parsing logic and control flow can be influenced from a single location in the code base. The trick is to eval-uate "log=utile_log" when the "-V" command-line argument is provided (or assign ARG_ARCH to the user-supplied value after "-a"). Using the $log variable invokes the function, such as in:

    preprocess() {
      $log "Preprocess"
    }

If "-V" isn't supplied, then every invocation of $log simply returns without printing a message. The upshot is a reduction in conditional statements. Function pointers FTW. I wrote about this technique in my Typesetting Markdown series:

https://dave.autonoma.ca/blog/2019/05/22/typesetting-markdow...

Here's a rudimentary implementation and example usage to wet your whistle:

https://github.com/DaveJarvis/keenwrite/blob/master/scripts/...

https://github.com/DaveJarvis/keenwrite/blob/master/installe...