Dec 27, 2020
README
Go Flag Utils
This is a Go library that provides a few types you can use with flag.Var().
Sample Code
There are detailed examples for each type on pkg.go.dev, but here's a quick example:
// Default to red
var color flagutils.RGB{
R: 0xff,
}
flag.Var(
&color,
"color",
"The color to use",
)
var featureA, featureB flagutils.OneOf
flagutils.GroupOneOf(&featureA, &featureB)
flag.Var(
&featureA,
"featureA",
"Run feature A, unsets featureB",
)
flag.Var(
&featureB,
"featureB",
"Run feature B, unsets featureA",
)
flag.Parse()
switch {
case featureA.Bool:
// Run feature A
case featureB.Bool:
// Run feature B
}
License
Documentation
Overview ¶
Package flagutils provides a few types you can use with flag.Var().
Please refer to the examples to see more details.
Index ¶
Examples ¶
Constants ¶
Variables ¶
Functions ¶
func GroupAllOneOf ¶
GroupAllOneOf group all OneOf flag values inside the FlagSet together.
It finds all OneOf values in the FlagSet, then calls GroupOneOf.
func GroupOneOf ¶
func GroupOneOf(values ...*OneOf)
GroupOneOf groups OneOf values together.
Please note that in case of regrouping, it only affects the values in the new group. For example say you have a previous group:
var a, b, c OneOf GroupOneOf(&a, &b, &c)
Then you regroup a and b:
GroupOneOf(&a, &b)
After the second GroupOneOf, a and b have the group info of each other, but c still records the group info of all of them. You will need to also regroup c with itself to complete the regrouping:
GroupOneOf(&c)
Types ¶
type OneOf ¶
type OneOf struct {
Bool bool
// contains filtered or unexported fields
}
OneOf is a flag type that works like bool, but can be grouped together.
When you group several OneOf values together, (via GroupOneOf or GroupAllOneOf) whenever one of them is set to true, the rest of the group will be set to false automatically.
It implements flag.Getter interface.
Example ¶
This example demostrates how to use OneOf in your program.
Code:
package main
import (
"flag"
"fmt"
"os"
"go.yhsif.com/flagutils"
)
func main() {
// Or use flag.CommandLine instead.
fs := flag.NewFlagSet("", flag.ExitOnError)
// Define 3 features, can only run one of them at a time.
var a, b, c flagutils.OneOf
fs.Var(&a, "featureA", "Run feature A, unsets featureB and featureC")
fs.Var(&b, "featureB", "Run feature B, unsets featureA and featureC")
fs.Var(&c, "featureC", "Run feature C, unsets featureA and featureB")
// You can also use
// flagutils.GroupAllOneOf(fs)
// if you don't have any other OneOf flag values.
flagutils.GroupOneOf(&a, &b, &c)
// TODO: Set other flags here.
fs.Parse(os.Args[1:])
// Now your program supports -featureA, -featureB, and -featureC args,
// and the last one in the command line overrides previous one(s).
//
// This means you can define a bash (or other shell) alias to specify a
// default feature, e.g.:
// alias my-cmd='my-cmd -featureA'
// and still be able to override it in command line:
// my-cmd -featureB
// which is actually
// my-cmd -featureA -featureB
// and runs featureB instead of featureA.
switch {
default:
// Please note that OneOf group only guarantees that at most one of the
// values will be set to true. It's still possible that all of them are
// false.
fmt.Fprintln(
os.Stderr,
"You have to specify one of -featureA, -featureB, or -featureC flags.",
)
os.Exit(-1)
case a.Bool:
// TODO: Implement feature A here.
case b.Bool:
// TODO: Implement feature B here.
case c.Bool:
// TODO: Implement feature C here.
}
}
type RGB ¶
RGB is a flag type that can be used for RGB colors.
It converts between string format "rrggbb" (no leading "#") and RGB color.
It implements color.Color and flag.Getter interfaces.
Example ¶
This example demostrates how to use RGB in your program.
Code:
package main
import (
"flag"
"fmt"
"go.yhsif.com/flagutils"
)
func main() {
fs := flag.NewFlagSet("", flag.ExitOnError)
// Default value
color := flagutils.RGB{
R: 0xff,
}
fs.Var(&color, "color", "the color you want")
fs.Parse([]string{"-color", "0000ff"})
fmt.Println(&color)
fmt.Println(color.RGBA())
}
0000ff 0 0 65535 0
type RGBA ¶
RGBA is a flag type that can be used for RGBA colors.
It converts between string format "rrggbbaa" (no leading "#") and RGBA color.
It implements color.Color and flag.Getter interfaces.
Example ¶
This example demostrates how to use RGBA in your program.
Code:
package main
import (
"flag"
"fmt"
"go.yhsif.com/flagutils"
)
func main() {
fs := flag.NewFlagSet("", flag.ExitOnError)
// Default value
color := flagutils.RGBA{
R: 0xff,
}
fs.Var(&color, "color", "the color you want")
fs.Parse([]string{"-color", "ff000080"})
fmt.Println(&color)
fmt.Println(color.RGBA())
}
ff000080 65535 0 0 32896
Source Files
Valid 
Stable version