required-args

Required vs Optional Arguments

The purpose of this example is to demonstrate the difference between required and optional arguments using string arguments.

Setup

The first step for any project is to build a new parser:

parser := argparse.NewParser("Required-args", "Example of required vs optional arguments")

For this demonstration, two shorthand arguments are used:

// Required shorthand argument
foo := parser.String("f", "foo", &argparse.Options{Required: true, Help: "foo is a required string option"})

// Optional shorthand argument
bar := parser.String("b", "bar", &argparse.Options{Required:false, Help: "bar is not a required option"})

foo is a required string argument, and bar is an optional string argument.

Using required-arguments.go without foo demonstrates this:

$ go run required-args.go
[-f|--foo] is required
usage: Required-args [-h|--help] -f|--foo "<value>" [-b|--bar "<value>"]

                     Example of required vs optional arguments

Arguments:

   -h   --help    Print help information
   -f   --foo     foo is a required string option
   -b   --bar     bar is not a required option

Output when foo is provided:

$ go run required-args.go --foo foo
Provided arguments:
foo (required): foo