opts.go is lightweight package for POSIX- and GNU-style options for go.

Important features that opts.go has:

• Automatic help screen generation
• Support for both short and long options (-o and --opt)
• Support for multiple short options in one argument
  • Including the case where the last option requires an argument
• Automatically allows both -I file and -Ifile formats.
• Support for options being specified multiple times, with different values
• Support for optional arguments.

Things opts.go lacks, by design:

• All arguments to options are strings.
• opts.go does not support multiple mandatory arguments to a single option

``` package main

import ( "fmt" "./opts" )

func printVersion() { fmt.Printf("VERSION\n") }

var showVersion = opts.Flag("", "--version", "Description") var output = opts.Half("-o", "--output", "write output to file", "", "output") var format = opts.Single("-f", "--format", "the output format to use", "csv") var include = opts.Multi("-I", "--include", "files to include", "file")

func main() { opts.Parse() if *showVersion { printVersion() } if *output != "" { fmt.Printf("Writing output to %s\n", *output) } fmt.Printf("Using format %s\n", *format) for _, file := range *include { fmt.Printf("Including %s\n", file) } } ```

./hello --output -f myformat Bob -I myfile -Imyotherfile --include=yetanotherfile