diff options
Diffstat (limited to 'vendor/github.com/victorhaggqvist/pflag/README.md')
| -rw-r--r-- | vendor/github.com/victorhaggqvist/pflag/README.md | 157 |
1 files changed, 157 insertions, 0 deletions
diff --git a/vendor/github.com/victorhaggqvist/pflag/README.md b/vendor/github.com/victorhaggqvist/pflag/README.md new file mode 100644 index 0000000..d9b189f --- /dev/null +++ b/vendor/github.com/victorhaggqvist/pflag/README.md @@ -0,0 +1,157 @@ +[](https://travis-ci.org/ogier/pflag) + +## Description + +pflag is a drop-in replacement for Go's flag package, implementing +POSIX/GNU-style --flags. + +pflag is compatible with the [GNU extensions to the POSIX recommendations +for command-line options][1]. For a more precise description, see the +"Command-line flag syntax" section below. + +[1]: http://www.gnu.org/software/libc/manual/html_node/Argument-Syntax.html + +pflag is available under the same style of BSD license as the Go language, +which can be found in the LICENSE file. + +## Installation + +pflag is available using the standard `go get` command. + +Install by running: + + go get github.com/ogier/pflag + +Run tests by running: + + go test github.com/ogier/pflag + +## Usage + +pflag is a drop-in replacement of Go's native flag package. If you import +pflag under the name "flag" then all code should continue to function +with no changes. + +``` go +import flag "github.com/ogier/pflag" +``` + +There is one exception to this: if you directly instantiate the Flag struct +there is one more field "Shorthand" that you will need to set. +Most code never instantiates this struct directly, and instead uses +functions such as String(), BoolVar(), and Var(), and is therefore +unaffected. + +Define flags using flag.String(), Bool(), Int(), etc. + +This declares an integer flag, -flagname, stored in the pointer ip, with type *int. + +``` go +var ip *int = flag.Int("flagname", 1234, "help message for flagname") +``` + +If you like, you can bind the flag to a variable using the Var() functions. + +``` go +var flagvar int +func init() { + flag.IntVar(&flagvar, "flagname", 1234, "help message for flagname") +} +``` + +Or you can create custom flags that satisfy the Value interface (with +pointer receivers) and couple them to flag parsing by + +``` go +flag.Var(&flagVal, "name", "help message for flagname") +``` + +For such flags, the default value is just the initial value of the variable. + +After all flags are defined, call + +``` go +flag.Parse() +``` + +to parse the command line into the defined flags. + +Flags may then be used directly. If you're using the flags themselves, +they are all pointers; if you bind to variables, they're values. + +``` go +fmt.Println("ip has value ", *ip) +fmt.Println("flagvar has value ", flagvar) +``` + +After parsing, the arguments after the flag are available as the +slice flag.Args() or individually as flag.Arg(i). +The arguments are indexed from 0 through flag.NArg()-1. + +The pflag package also defines some new functions that are not in flag, +that give one-letter shorthands for flags. You can use these by appending +'P' to the name of any function that defines a flag. + +``` go +var ip = flag.IntP("flagname", "f", 1234, "help message") +var flagvar bool +func init() { + flag.BoolVarP("boolname", "b", true, "help message") +} +flag.VarP(&flagVar, "varname", "v", 1234, "help message") +``` + +Shorthand letters can be used with single dashes on the command line. +Boolean shorthand flags can be combined with other shorthand flags. + +The default set of command-line flags is controlled by +top-level functions. The FlagSet type allows one to define +independent sets of flags, such as to implement subcommands +in a command-line interface. The methods of FlagSet are +analogous to the top-level functions for the command-line +flag set. + +## Command line flag syntax + +``` +--flag // boolean flags only +--flag=x +``` + +Unlike the flag package, a single dash before an option means something +different than a double dash. Single dashes signify a series of shorthand +letters for flags. All but the last shorthand letter must be boolean flags. + +``` +// boolean flags +-f +-abc + +// non-boolean flags +-n 1234 +-Ifile + +// mixed +-abcs "hello" +-abcn1234 +``` + +Flag parsing stops after the terminator "--". Unlike the flag package, +flags can be interspersed with arguments anywhere on the command line +before this terminator. + +Integer flags accept 1234, 0664, 0x1234 and may be negative. +Boolean flags (in their long form) accept 1, 0, t, f, true, false, +TRUE, FALSE, True, False. +Duration flags accept any input valid for time.ParseDuration. + +## More info + +You can see the full reference documentation of the pflag package +[at godoc.org][3], or through go's standard documentation system by +running `godoc -http=:6060` and browsing to +[http://localhost:6060/pkg/github.com/ogier/pflag][2] after +installation. + +[2]: http://localhost:6060/pkg/github.com/ogier/pflag +[3]: http://godoc.org/github.com/ogier/pflag |