This project is not maintained anymore and is archived. Feel free to fork and make your own changes if needed. For more detail read my blog post: Taking an indefinite sabbatical from my projects
Thanks to everyone for their valuable feedback and contributions.
Flags is a low level package for parsing or managing single flag arguments and their associated values from a list of arguments. It's useful for CLI applications or creating logic for parsing arguments(custom or os.Args) manually.
Note that there is no context available for flags. You need to know upfront how flags are supposed to be parsed.
Checkout the usage below for examples:
go get github.com/fatih/flagsLet us define three flags. Flags needs to be compatible with the flag package.
args := []string{"--key", "123", "--name=example", "--debug"}Check if a flag exists in the argument list
flags.Has("key", args) // true
flags.Has("--key", args) // true
flags.Has("secret", args) // falseGet the value for from a flag name
val, _ := flags.Value("--key", args) // val -> "123"
val, _ := flags.Value("name", args) // val -> "example"
val, _ := flags.Value("debug", args) // val -> "" (means true boolean)Exclude a flag and it's value from the argument list
rArgs := flags.Exclude("key", args) // rArgs -> ["--name=example", "--debug"]
rArgs := flags.Exclude("name", args) // rArgs -> ["--key", "123", "--debug"]
rArgs := flags.Exclude("foo", args) // rArgs -> ["--key", "123", "--name=example "--debug"]Is a flag in its valid representation (compatible with the flag package)?
flags.Valid("foo") // false
flags.Valid("--foo") // true
flags.Valid("-key=val") // true
flags.Valid("-name=") // trueParse a flag and return the name
name, _ := flags.Parse("foo") // returns error, because foo is invalid
name, _ := flags.Parse("--foo") // name -> "foo
name, _ := flags.Parse("-foo") // name -> "foo
name, _ := flags.Parse("-foo=value") // name -> "foo
name, _ := flags.Parse("-foo=") // name -> "fooParse into a []string or []int variable
os.Args = []string{"cmd", "--key", "123,456", "--regions", "us-east-1,eu-west-1"}
var regions []string
var ids []int
flags.StringSliceVar(®ions, []string{}, "to", "Regions to be used")
flags.IntSliceVar(&ids, []int{678}, "ids", "Servers to be used")
flag.Parse()
fmt.Println(regions) // prints: ["us-east-1", "eu-west-1"]
fmt.Println(ids) // prints: [123,456]Or plug it into a flag.FlagSet instance:
args := []string{"--key", "123,456", "--regions", "us-east-1,eu-west-1"}
var regions []string
var ids []int
f := flag.NewFlagSet()
f.Var(flags.NewStringSlice(nil, ®ions), "to", "Regions to be used")
f.Var(flags.NewIntSlice(nil, &ids), "to", "Regions to be used")
f.Parse(args)
fmt.Println(regions) // prints: ["us-east-1", "eu-west-1"]
fmt.Println(ids) // prints: [123,456]
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