A simple set of CLI argument parsing procedures using std/parseopt that covers the majority of basic cases for parsing CLI arguments.

simpleargs.nim

# by Chris Collazo
# Released to the public domain

import std/parseopt

# `short` is optional
proc get_option*(oparser: var OptParser, name: string, default: string, short: string = ""): string =
    for kind, key, val in oparser.getopt():
        if kind == cmdLongOption and key == name:
            return val
        elif short != "" and kind == cmdShortOption and key == short:
            return val
    return default

# For options which are only short
proc get_option_short*(oparser: var OptParser, short: string, default: string): string =
    for kind, key, val in oparser.getopt():
        if kind == cmdShortOption and key == short:
            return val
    return default

# `short` is optional
proc get_flag*(oparser: var OptParser, name: string, short: string = ""): bool =
    for kind, key, val in oparser.getopt():
        if kind == cmdLongOption and key == name:
            return true
        elif short != "" and kind == cmdShortOption and key == short:
            return true
    return false

# For flags which are only short
proc get_flag_short*(oparser: var OptParser, short: string): bool =
    for kind, key, val in oparser.getopt():
        if kind == cmdShortOption and key == short:
            return true
    return false

# For positional args
proc get_arg_at_index*(oparser: var OptParser, index: int): string =
    var i = 0
    for kind, key, val in oparser.getopt():
        if i == index and kind == cmdArgument:
            return key
        i += 1
    return ""

# First argument, which is often a command, is at position 0
proc command_was*(oparser: var OptParser, cmd: string): bool =
    oparser.get_arg_at_index(0) == cmd

# Second argument, which is sometimes a subcommand, is at position 1
proc subcommand_was*(oparser: var OptParser, cmd: string): bool =
    oparser.get_arg_at_index(1) == cmd



when isMainModule:
    import std/strformat
    import std/strutils

    var cli = init_opt_parser()
    echo &"""Command was `foo`?: {cli.command_was("foo")}"""
    echo &"""Subcommand was `bar`?: {cli.subcommand_was("bar")}"""
    echo &"""Option `switch` was: {cli.get_option("switch", "none", short = "s")}"""
    echo &"""Option `quality` was: {cli.get_option("quality", "100", short = "q").parse_int()}"""
    echo &"""Flag `convert` was: {cli.get_flag("convert", short = "c")}"""
    echo &"""Option `t` was: {cli.get_option_short("t", "none")}"""
    echo &"""Flag a was: {cli.get_flag_short("a")}"""
    echo &"""Flag e was: {cli.get_flag_short("e")}"""
    echo &"""Flag i was: {cli.get_flag_short("i")}"""
    echo &"""Flag o was: {cli.get_flag_short("o")}"""
    echo &"""Flag u was: {cli.get_flag_short("u")}"""