whiteflag

whiteflag

A sane flag-package for gophers who just need some CLI flags in Golang projects, not command-structuring frameworks for space ships. If you waved a white flag on the usual whoppers, whiteflag is here to assist.

Features

• simply provides FlagPresent() to check for specified flags, and GetBool|Int|String() to access their values (these functions can be utilized directly without further setup of each flag)
• allows you to distinguish between absent and zero-valued flags
• -h/--help prints basic generated Usage/Help text (see examples)
• Default values for flags can be specified
• Required flags can be achieved implicitly (see examples)

Examples

Please have a look at the comprehensive example source file.

Basic

The following snippet would print "gopher" when called with -p gopher.

package main

import wf "github.com/danielb42/whiteflag"

func main() {
    if wf.FlagPresent("p") {
        println(wf.GetString("p"))
    }
}

With long+required+default flags and nice 'Usage' output

The next snippet will print the sum of two integers given through -x and -y. For y we specify a default value. Let's also associate long flags to the short flags so we could equivalently run the snippet with --first and --second. Aliasing flags makes them known to the Usage/Help text generation.

package main

import wf "github.com/danielb42/whiteflag"

func main() {
    wf.Alias("x", "first",  "The first number.")
    wf.Alias("y", "second", "The second number.")
    wf.SetIntDefault("y", 42)

    // we don't do a FlagPresent() check on x und y before Get'ting them so
    // the program will exit if x is not specified, thus making x 'required'.
    // For a missing y flag, the default value of 42 would be used.

    x := wf.GetInt("x")
    y := wf.GetInt("y")
    sum := x + y
    println("sum of x and y:", sum)
}

For the snippet above the following Usage/Help text would be available through -h/--help:

Usage: ./example <flags>

Flags:
  -x  --first    The first number.
  -y  --second   The second number.

License

MIT