pflag

package
v1.1.0-alpha.0 Latest Latest
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 Go to latest Published: Jul 11, 2015 License: BSD-3-Clause, Apache-2.0 Imports: 10 Imported by: 0

README

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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. For a more precise description, see the "Command-line flag syntax" section below.

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.

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.

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.

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

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

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.

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.

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.

Mutating or "Normalizing" Flag names

It is possible to set a custom flag name 'normalization function.' It allows flag names to be mutated both when created in the code and when used on the command line to some 'normalized' form. The 'normalized' form is used for comparison. Two examples of using the custom normalization func follow.

Example #1: You want -, _, and . in flags to compare the same. aka --my-flag == --my_flag == --my.flag

func wordSepNormalizeFunc(f *pflag.FlagSet, name string) pflag.NormalizedName {
	from := []string{"-", "_"}
	to := "."
	for _, sep := range from {
		name = strings.Replace(name, sep, to, -1)
	}
	return pflag.NormalizedName(name)
}

myFlagSet.SetNormalizeFunc(wordSepNormalizeFunc)

Example #2: You want to alias two flags. aka --old-flag-name == --new-flag-name

func aliasNormalizeFunc(f *pflag.FlagSet, name string) pflag.NormalizedName {
	switch name {
	case "old-flag-name":
		name = "new-flag-name"
		break
	}
	return pflag.NormalizedName(name)
}

myFlagSet.SetNormalizeFunc(aliasNormalizeFunc)

More info

You can see the full reference documentation of the pflag package at godoc.org, or through go's standard documentation system by running godoc -http=:6060 and browsing to http://localhost:6060/pkg/github.com/ogier/pflag after installation.

Documentation

Overview

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. See http://www.gnu.org/software/libc/manual/html_node/Argument-Syntax.html

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. 

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. 

var ip = flag.Int("flagname", 1234, "help message for flagname")

If you like, you can bind the flag to a variable using the Var() functions. 

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 

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 

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. 

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. 

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.

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.

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.

Example 
// These examples demonstrate more intricate uses of the flag package.
package main

import (
	"errors"
	"fmt"
	"strings"
	"time"

	flag "github.com/spf13/pflag"
)

// Example 1: A single string flag called "species" with default value "gopher".
var species = flag.String("species", "gopher", "the species we are studying")

// Example 2: A flag with a shorthand letter.
var gopherType = flag.StringP("gopher_type", "g", "pocket", "the variety of gopher")

// Example 3: A user-defined flag type, a slice of durations.
type interval []time.Duration

// String is the method to format the flag's value, part of the flag.Value interface.
// The String method's output will be used in diagnostics.
func (i *interval) String() string {
	return fmt.Sprint(*i)
}

func (i *interval) Type() string {
	return "interval"
}

// Set is the method to set the flag value, part of the flag.Value interface.
// Set's argument is a string to be parsed to set the flag.
// It's a comma-separated list, so we split it.
func (i *interval) Set(value string) error {
	// If we wanted to allow the flag to be set multiple times,
	// accumulating values, we would delete this if statement.
	// That would permit usages such as
	//	-deltaT 10s -deltaT 15s
	// and other combinations.
	if len(*i) > 0 {
		return errors.New("interval flag already set")
	}
	for _, dt := range strings.Split(value, ",") {
		duration, err := time.ParseDuration(dt)
		if err != nil {
			return err
		}
		*i = append(*i, duration)
	}
	return nil
}

// Define a flag to accumulate durations. Because it has a special type,
// we need to use the Var function and therefore create the flag during
// init.

var intervalFlag interval

func init() {
	// Tie the command-line flag to the intervalFlag variable and
	// set a usage message.
	flag.Var(&intervalFlag, "deltaT", "comma-separated list of intervals to use between events")
}

func main() {
	// All the interesting pieces are with the variables declared above, but
	// to enable the flag package to see the flags defined there, one must
	// execute, typically at the start of main (not init!):
	//	flag.Parse()
	// We don't run it here because this is not a main function and
	// the testing suite has already parsed the flags.
}

Output:

Index

Examples

Constants

This section is empty.

Variables

View Source 
var CommandLine = NewFlagSet(os.Args[0], ExitOnError)

The default set of command-line flags, parsed from os.Args.

View Source 
var ErrHelp = errors.New("pflag: help requested")

ErrHelp is the error returned if the flag -help is invoked but no such flag is defined.

View Source 
var Usage = func() {
	fmt.Fprintf(os.Stderr, "Usage of %s:\n", os.Args[0])
	PrintDefaults()
}

Usage prints to standard error a usage message documenting all defined command-line flags. The function is a variable that may be changed to point to a custom function.

Functions

func Arg 

func Arg(i int) string

Arg returns the i'th command-line argument. Arg(0) is the first remaining argument after flags have been processed.

func Args 

func Args() []string

Args returns the non-flag command-line arguments.

func Bool 

func Bool(name string, value bool, usage string) *bool

Bool defines a bool flag with specified name, default value, and usage string. The return value is the address of a bool variable that stores the value of the flag.

func BoolP 

func BoolP(name, shorthand string, value bool, usage string) *bool

Like Bool, but accepts a shorthand letter that can be used after a single dash.

func BoolVar 

func BoolVar(p *bool, name string, value bool, usage string)

BoolVar defines a bool flag with specified name, default value, and usage string. The argument p points to a bool variable in which to store the value of the flag.

func BoolVarP 

func BoolVarP(p *bool, name, shorthand string, value bool, usage string)

Like BoolVar, but accepts a shorthand letter that can be used after a single dash.

func Duration 

func Duration(name string, value time.Duration, usage string) *time.Duration

Duration defines a time.Duration flag with specified name, default value, and usage string. The return value is the address of a time.Duration variable that stores the value of the flag.

func DurationP 

func DurationP(name, shorthand string, value time.Duration, usage string) *time.Duration

Like Duration, but accepts a shorthand letter that can be used after a single dash.

func DurationVar 

func DurationVar(p *time.Duration, name string, value time.Duration, usage string)

DurationVar defines a time.Duration flag with specified name, default value, and usage string. The argument p points to a time.Duration variable in which to store the value of the flag.

func DurationVarP 

func DurationVarP(p *time.Duration, name, shorthand string, value time.Duration, usage string)

Like DurationVar, but accepts a shorthand letter that can be used after a single dash.

func Float32 

func Float32(name string, value float32, usage string) *float32

Float32 defines a float32 flag with specified name, default value, and usage string. The return value is the address of a float32 variable that stores the value of the flag.

func Float32P 

func Float32P(name, shorthand string, value float32, usage string) *float32

Like Float32, but accepts a shorthand letter that can be used after a single dash.

func Float32Var 

func Float32Var(p *float32, name string, value float32, usage string)

Float32Var defines a float32 flag with specified name, default value, and usage string. The argument p points to a float32 variable in which to store the value of the flag.

func Float32VarP 

func Float32VarP(p *float32, name, shorthand string, value float32, usage string)

Like Float32Var, but accepts a shorthand letter that can be used after a single dash.

func Float64 

func Float64(name string, value float64, usage string) *float64

Float64 defines a float64 flag with specified name, default value, and usage string. The return value is the address of a float64 variable that stores the value of the flag.

func Float64P 

func Float64P(name, shorthand string, value float64, usage string) *float64

Like Float64, but accepts a shorthand letter that can be used after a single dash.

func Float64Var 

func Float64Var(p *float64, name string, value float64, usage string)

Float64Var defines a float64 flag with specified name, default value, and usage string. The argument p points to a float64 variable in which to store the value of the flag.

func Float64VarP 

func Float64VarP(p *float64, name, shorthand string, value float64, usage string)

Like Float64Var, but accepts a shorthand letter that can be used after a single dash.

func IP 

func IP(name string, value net.IP, usage string) *net.IP

IP defines an net.IP flag with specified name, default value, and usage string. The return value is the address of an net.IP variable that stores the value of the flag.

func IPMask 

func IPMask(name string, value net.IPMask, usage string) *net.IPMask

IPMask defines an net.IPMask flag with specified name, default value, and usage string. The return value is the address of an net.IPMask variable that stores the value of the flag.

func IPMaskP 

func IPMaskP(name, shorthand string, value net.IPMask, usage string) *net.IPMask

Like IP, but accepts a shorthand letter that can be used after a single dash.

func IPMaskVar 

func IPMaskVar(p *net.IPMask, name string, value net.IPMask, usage string)

IPMaskVar defines an net.IPMask flag with specified name, default value, and usage string. The argument p points to an net.IPMask variable in which to store the value of the flag.

func IPMaskVarP 

func IPMaskVarP(p *net.IPMask, name, shorthand string, value net.IPMask, usage string)

Like IPMaskVar, but accepts a shorthand letter that can be used after a single dash.

func IPP 

func IPP(name, shorthand string, value net.IP, usage string) *net.IP

Like IP, but accepts a shorthand letter that can be used after a single dash.

func IPVar 

func IPVar(p *net.IP, name string, value net.IP, usage string)

IPVar defines an net.IP flag with specified name, default value, and usage string. The argument p points to an net.IP variable in which to store the value of the flag.

func IPVarP 

func IPVarP(p *net.IP, name, shorthand string, value net.IP, usage string)

Like IPVar, but accepts a shorthand letter that can be used after a single dash.

func Int 

func Int(name string, value int, usage string) *int

Int defines an int flag with specified name, default value, and usage string. The return value is the address of an int variable that stores the value of the flag.

func Int32 

func Int32(name string, value int32, usage string) *int32

Int32 defines an int32 flag with specified name, default value, and usage string. The return value is the address of an int32 variable that stores the value of the flag.

func Int32P 

func Int32P(name, shorthand string, value int32, usage string) *int32

Like Int32, but accepts a shorthand letter that can be used after a single dash.

func Int32Var 

func Int32Var(p *int32, name string, value int32, usage string)

Int32Var defines an int32 flag with specified name, default value, and usage string. The argument p points to an int32 variable in which to store the value of the flag.

func Int32VarP 

func Int32VarP(p *int32, name, shorthand string, value int32, usage string)

Like Int32Var, but accepts a shorthand letter that can be used after a single dash.

func Int64 

func Int64(name string, value int64, usage string) *int64

Int64 defines an int64 flag with specified name, default value, and usage string. The return value is the address of an int64 variable that stores the value of the flag.

func Int64P 

func Int64P(name, shorthand string, value int64, usage string) *int64

Like Int64, but accepts a shorthand letter that can be used after a single dash.

func Int64Var 

func Int64Var(p *int64, name string, value int64, usage string)

Int64Var defines an int64 flag with specified name, default value, and usage string. The argument p points to an int64 variable in which to store the value of the flag.

func Int64VarP 

func Int64VarP(p *int64, name, shorthand string, value int64, usage string)

Like Int64Var, but accepts a shorthand letter that can be used after a single dash.

func Int8 

func Int8(name string, value int8, usage string) *int8

Int8 defines an int8 flag with specified name, default value, and usage string. The return value is the address of an int8 variable that stores the value of the flag.

func Int8P 

func Int8P(name, shorthand string, value int8, usage string) *int8

Like Int8, but accepts a shorthand letter that can be used after a single dash.

func Int8Var 

func Int8Var(p *int8, name string, value int8, usage string)

Int8Var defines an int8 flag with specified name, default value, and usage string. The argument p points to an int8 variable in which to store the value of the flag.

func Int8VarP 

func Int8VarP(p *int8, name, shorthand string, value int8, usage string)

Like Int8Var, but accepts a shorthand letter that can be used after a single dash.

func IntP 

func IntP(name, shorthand string, value int, usage string) *int

Like Int, but accepts a shorthand letter that can be used after a single dash.

func IntVar 

func IntVar(p *int, name string, value int, usage string)

IntVar defines an int flag with specified name, default value, and usage string. The argument p points to an int variable in which to store the value of the flag.

func IntVarP 

func IntVarP(p *int, name, shorthand string, value int, usage string)

Like IntVar, but accepts a shorthand letter that can be used after a single dash.

func NArg 

func NArg() int

NArg is the number of arguments remaining after flags have been processed.

func NFlag 

func NFlag() int

NFlag returns the number of command-line flags that have been set.

func Parse 

func Parse()

Parse parses the command-line flags from os.Args[1:]. Must be called after all flags are defined and before flags are accessed by the program.

func ParseIPv4Mask 

func ParseIPv4Mask(s string) net.IPMask

Parse IPv4 netmask written in IP form (e.g. 255.255.255.0). This function should really belong to the net package.

func Parsed 

func Parsed() bool

Parsed returns true if the command-line flags have been parsed.

func PrintDefaults 

func PrintDefaults()

PrintDefaults prints to standard error the default values of all defined command-line flags.

func Set 

func Set(name, value string) error

Set sets the value of the named command-line flag.

func SetInterspersed 

func SetInterspersed(interspersed bool)

Whether to support interspersed option/non-option arguments.

func String 

func String(name string, value string, usage string) *string

String defines a string flag with specified name, default value, and usage string. The return value is the address of a string variable that stores the value of the flag.

func StringP 

func StringP(name, shorthand string, value string, usage string) *string

Like String, but accepts a shorthand letter that can be used after a single dash.

func StringVar 

func StringVar(p *string, name string, value string, usage string)

StringVar defines a string flag with specified name, default value, and usage string. The argument p points to a string variable in which to store the value of the flag.

func StringVarP 

func StringVarP(p *string, name, shorthand string, value string, usage string)

Like StringVar, but accepts a shorthand letter that can be used after a single dash.

func Uint 

func Uint(name string, value uint, usage string) *uint

Uint defines a uint flag with specified name, default value, and usage string. The return value is the address of a uint variable that stores the value of the flag.

func Uint16 

func Uint16(name string, value uint16, usage string) *uint16

Uint16 defines a uint flag with specified name, default value, and usage string. The return value is the address of a uint variable that stores the value of the flag.

func Uint16P 

func Uint16P(name, shorthand string, value uint16, usage string) *uint16

Like Uint16, but accepts a shorthand letter that can be used after a single dash.

func Uint16Var 

func Uint16Var(p *uint16, name string, value uint16, usage string)

Uint16Var defines a uint flag with specified name, default value, and usage string. The argument p points to a uint variable in which to store the value of the flag.

func Uint16VarP 

func Uint16VarP(p *uint16, name, shorthand string, value uint16, usage string)

Like Uint16Var, but accepts a shorthand letter that can be used after a single dash.

func Uint32 

func Uint32(name string, value uint32, usage string) *uint32

Uint32 defines a uint32 flag with specified name, default value, and usage string. The return value is the address of a uint32 variable that stores the value of the flag.

func Uint32P 

func Uint32P(name, shorthand string, value uint32, usage string) *uint32

Like Uint32, but accepts a shorthand letter that can be used after a single dash.

func Uint32Var 

func Uint32Var(p *uint32, name string, value uint32, usage string)

Uint32Var defines a uint32 flag with specified name, default value, and usage string. The argument p points to a uint32 variable in which to store the value of the flag.

func Uint32VarP 

func Uint32VarP(p *uint32, name, shorthand string, value uint32, usage string)

Like Uint32Var, but accepts a shorthand letter that can be used after a single dash.

func Uint64 

func Uint64(name string, value uint64, usage string) *uint64

Uint64 defines a uint64 flag with specified name, default value, and usage string. The return value is the address of a uint64 variable that stores the value of the flag.

func Uint64P 

func Uint64P(name, shorthand string, value uint64, usage string) *uint64

Like Uint64, but accepts a shorthand letter that can be used after a single dash.

func Uint64Var 

func Uint64Var(p *uint64, name string, value uint64, usage string)

Uint64Var defines a uint64 flag with specified name, default value, and usage string. The argument p points to a uint64 variable in which to store the value of the flag.

func Uint64VarP 

func Uint64VarP(p *uint64, name, shorthand string, value uint64, usage string)

Like Uint64Var, but accepts a shorthand letter that can be used after a single dash.

func Uint8 

func Uint8(name string, value uint8, usage string) *uint8

Uint8 defines a uint8 flag with specified name, default value, and usage string. The return value is the address of a uint8 variable that stores the value of the flag.

func Uint8P 

func Uint8P(name, shorthand string, value uint8, usage string) *uint8

Like Uint8, but accepts a shorthand letter that can be used after a single dash.

func Uint8Var 

func Uint8Var(p *uint8, name string, value uint8, usage string)

Uint8Var defines a uint8 flag with specified name, default value, and usage string. The argument p points to a uint8 variable in which to store the value of the flag.

func Uint8VarP 

func Uint8VarP(p *uint8, name, shorthand string, value uint8, usage string)

Like Uint8Var, but accepts a shorthand letter that can be used after a single dash.

func UintP 

func UintP(name, shorthand string, value uint, usage string) *uint

Like Uint, but accepts a shorthand letter that can be used after a single dash.

func UintVar 

func UintVar(p *uint, name string, value uint, usage string)

UintVar defines a uint flag with specified name, default value, and usage string. The argument p points to a uint variable in which to store the value of the flag.

func UintVarP 

func UintVarP(p *uint, name, shorthand string, value uint, usage string)

Like UintVar, but accepts a shorthand letter that can be used after a single dash.

func Var 

func Var(value Value, name string, usage string)

Var defines a flag with the specified name and usage string. The type and value of the flag are represented by the first argument, of type Value, which typically holds a user-defined implementation of Value. For instance, the caller could create a flag that turns a comma-separated string into a slice of strings by giving the slice the methods of Value; in particular, Set would decompose the comma-separated string into the slice.

func VarP 

func VarP(value Value, name, shorthand, usage string)

Like Var, but accepts a shorthand letter that can be used after a single dash.

func Visit 

func Visit(fn func(*Flag))

Visit visits the command-line flags in lexicographical order, calling fn for each. It visits only those flags that have been set.

func VisitAll 

func VisitAll(fn func(*Flag))

VisitAll visits the command-line flags in lexicographical order, calling fn for each. It visits all flags, even those not set.

Types

type ErrorHandling 

type ErrorHandling int

ErrorHandling defines how to handle flag parsing errors. 

const (
	ContinueOnError ErrorHandling = iota
	ExitOnError
	PanicOnError
)

type Flag 

type Flag struct {
	Name        string              // name as it appears on command line
	Shorthand   string              // one-letter abbreviated flag
	Usage       string              // help message
	Value       Value               // value as set
	DefValue    string              // default value (as text); for usage message
	Changed     bool                // If the user set the value (or if left to default)
	Deprecated  string              // If this flag is deprecated, this string is the new or now thing to use
	Annotations map[string][]string // used by cobra.Command  bash autocomple code
}

A Flag represents the state of a flag.

func Lookup 

func Lookup(name string) *Flag

Lookup returns the Flag structure of the named command-line flag, returning nil if none exists.

type FlagSet 

type FlagSet struct {
	// Usage is the function called when an error occurs while parsing flags.
	// The field is a function (not a method) that may be changed to point to
	// a custom error handler.
	Usage func()
	// contains filtered or unexported fields
}

A FlagSet represents a set of defined flags.

func NewFlagSet 

func NewFlagSet(name string, errorHandling ErrorHandling) *FlagSet

NewFlagSet returns a new, empty flag set with the specified name and error handling property.

func (*FlagSet) AddFlag 

func (f *FlagSet) AddFlag(flag *Flag)

func (*FlagSet) Arg 

func (f *FlagSet) Arg(i int) string

Arg returns the i'th argument. Arg(0) is the first remaining argument after flags have been processed.

func (*FlagSet) Args 

func (f *FlagSet) Args() []string

Args returns the non-flag arguments.

func (*FlagSet) Bool 

func (f *FlagSet) Bool(name string, value bool, usage string) *bool

Bool defines a bool flag with specified name, default value, and usage string. The return value is the address of a bool variable that stores the value of the flag.

func (*FlagSet) BoolP 

func (f *FlagSet) BoolP(name, shorthand string, value bool, usage string) *bool

Like Bool, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) BoolVar 

func (f *FlagSet) BoolVar(p *bool, name string, value bool, usage string)

BoolVar defines a bool flag with specified name, default value, and usage string. The argument p points to a bool variable in which to store the value of the flag.

func (*FlagSet) BoolVarP 

func (f *FlagSet) BoolVarP(p *bool, name, shorthand string, value bool, usage string)

Like BoolVar, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) Duration 

func (f *FlagSet) Duration(name string, value time.Duration, usage string) *time.Duration

Duration defines a time.Duration flag with specified name, default value, and usage string. The return value is the address of a time.Duration variable that stores the value of the flag.

func (*FlagSet) DurationP 

func (f *FlagSet) DurationP(name, shorthand string, value time.Duration, usage string) *time.Duration

Like Duration, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) DurationVar 

func (f *FlagSet) DurationVar(p *time.Duration, name string, value time.Duration, usage string)

DurationVar defines a time.Duration flag with specified name, default value, and usage string. The argument p points to a time.Duration variable in which to store the value of the flag.

func (*FlagSet) DurationVarP 

func (f *FlagSet) DurationVarP(p *time.Duration, name, shorthand string, value time.Duration, usage string)

Like DurationVar, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) FlagUsages 

func (f *FlagSet) FlagUsages() string

func (*FlagSet) Float32 

func (f *FlagSet) Float32(name string, value float32, usage string) *float32

Float32 defines a float32 flag with specified name, default value, and usage string. The return value is the address of a float32 variable that stores the value of the flag.

func (*FlagSet) Float32P 

func (f *FlagSet) Float32P(name, shorthand string, value float32, usage string) *float32

Like Float32, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) Float32Var 

func (f *FlagSet) Float32Var(p *float32, name string, value float32, usage string)

Float32Var defines a float32 flag with specified name, default value, and usage string. The argument p points to a float32 variable in which to store the value of the flag.

func (*FlagSet) Float32VarP 

func (f *FlagSet) Float32VarP(p *float32, name, shorthand string, value float32, usage string)

Like Float32Var, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) Float64 

func (f *FlagSet) Float64(name string, value float64, usage string) *float64

Float64 defines a float64 flag with specified name, default value, and usage string. The return value is the address of a float64 variable that stores the value of the flag.

func (*FlagSet) Float64P 

func (f *FlagSet) Float64P(name, shorthand string, value float64, usage string) *float64

Like Float64, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) Float64Var 

func (f *FlagSet) Float64Var(p *float64, name string, value float64, usage string)

Float64Var defines a float64 flag with specified name, default value, and usage string. The argument p points to a float64 variable in which to store the value of the flag.

func (*FlagSet) Float64VarP 

func (f *FlagSet) Float64VarP(p *float64, name, shorthand string, value float64, usage string)

Like Float64Var, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) GetNormalizeFunc added in v0.17.0 

func (f *FlagSet) GetNormalizeFunc() func(f *FlagSet, name string) NormalizedName

func (*FlagSet) HasFlags 

func (f *FlagSet) HasFlags() bool

func (*FlagSet) IP 

func (f *FlagSet) IP(name string, value net.IP, usage string) *net.IP

IP defines an net.IP flag with specified name, default value, and usage string. The return value is the address of an net.IP variable that stores the value of the flag.

func (*FlagSet) IPMask 

func (f *FlagSet) IPMask(name string, value net.IPMask, usage string) *net.IPMask

IPMask defines an net.IPMask flag with specified name, default value, and usage string. The return value is the address of an net.IPMask variable that stores the value of the flag.

func (*FlagSet) IPMaskP 

func (f *FlagSet) IPMaskP(name, shorthand string, value net.IPMask, usage string) *net.IPMask

Like IPMask, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) IPMaskVar 

func (f *FlagSet) IPMaskVar(p *net.IPMask, name string, value net.IPMask, usage string)

IPMaskVar defines an net.IPMask flag with specified name, default value, and usage string. The argument p points to an net.IPMask variable in which to store the value of the flag.

func (*FlagSet) IPMaskVarP 

func (f *FlagSet) IPMaskVarP(p *net.IPMask, name, shorthand string, value net.IPMask, usage string)

Like IPMaskVar, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) IPP 

func (f *FlagSet) IPP(name, shorthand string, value net.IP, usage string) *net.IP

Like IP, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) IPVar 

func (f *FlagSet) IPVar(p *net.IP, name string, value net.IP, usage string)

IPVar defines an net.IP flag with specified name, default value, and usage string. The argument p points to an net.IP variable in which to store the value of the flag.

func (*FlagSet) IPVarP 

func (f *FlagSet) IPVarP(p *net.IP, name, shorthand string, value net.IP, usage string)

Like IPVar, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) Init 

func (f *FlagSet) Init(name string, errorHandling ErrorHandling)

Init sets the name and error handling property for a flag set. By default, the zero FlagSet uses an empty name and the ContinueOnError error handling policy.

func (*FlagSet) Int 

func (f *FlagSet) Int(name string, value int, usage string) *int

Int defines an int flag with specified name, default value, and usage string. The return value is the address of an int variable that stores the value of the flag.

func (*FlagSet) Int32 

func (f *FlagSet) Int32(name string, value int32, usage string) *int32

Int32 defines an int32 flag with specified name, default value, and usage string. The return value is the address of an int32 variable that stores the value of the flag.

func (*FlagSet) Int32P 

func (f *FlagSet) Int32P(name, shorthand string, value int32, usage string) *int32

Like Int32, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) Int32Var 

func (f *FlagSet) Int32Var(p *int32, name string, value int32, usage string)

Int32Var defines an int32 flag with specified name, default value, and usage string. The argument p points to an int32 variable in which to store the value of the flag.

func (*FlagSet) Int32VarP 

func (f *FlagSet) Int32VarP(p *int32, name, shorthand string, value int32, usage string)

Like Int32Var, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) Int64 

func (f *FlagSet) Int64(name string, value int64, usage string) *int64

Int64 defines an int64 flag with specified name, default value, and usage string. The return value is the address of an int64 variable that stores the value of the flag.

func (*FlagSet) Int64P 

func (f *FlagSet) Int64P(name, shorthand string, value int64, usage string) *int64

Like Int64, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) Int64Var 

func (f *FlagSet) Int64Var(p *int64, name string, value int64, usage string)

Int64Var defines an int64 flag with specified name, default value, and usage string. The argument p points to an int64 variable in which to store the value of the flag.

func (*FlagSet) Int64VarP 

func (f *FlagSet) Int64VarP(p *int64, name, shorthand string, value int64, usage string)

Like Int64Var, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) Int8 

func (f *FlagSet) Int8(name string, value int8, usage string) *int8

Int8 defines an int8 flag with specified name, default value, and usage string. The return value is the address of an int8 variable that stores the value of the flag.

func (*FlagSet) Int8P 

func (f *FlagSet) Int8P(name, shorthand string, value int8, usage string) *int8

Like Int8, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) Int8Var 

func (f *FlagSet) Int8Var(p *int8, name string, value int8, usage string)

Int8Var defines an int8 flag with specified name, default value, and usage string. The argument p points to an int8 variable in which to store the value of the flag.

func (*FlagSet) Int8VarP 

func (f *FlagSet) Int8VarP(p *int8, name, shorthand string, value int8, usage string)

Like Int8Var, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) IntP 

func (f *FlagSet) IntP(name, shorthand string, value int, usage string) *int

Like Int, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) IntVar 

func (f *FlagSet) IntVar(p *int, name string, value int, usage string)

IntVar defines an int flag with specified name, default value, and usage string. The argument p points to an int variable in which to store the value of the flag.

func (*FlagSet) IntVarP 

func (f *FlagSet) IntVarP(p *int, name, shorthand string, value int, usage string)

Like IntVar, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) Lookup 

func (f *FlagSet) Lookup(name string) *Flag

Lookup returns the Flag structure of the named flag, returning nil if none exists.

func (*FlagSet) MarkDeprecated added in v0.17.0 

func (f *FlagSet) MarkDeprecated(name string, usageMessage string) error

Mark a flag deprecated in your program

func (*FlagSet) NArg 

func (f *FlagSet) NArg() int

NArg is the number of arguments remaining after flags have been processed.

func (*FlagSet) NFlag 

func (f *FlagSet) NFlag() int

NFlag returns the number of flags that have been set.

func (*FlagSet) Parse 

func (f *FlagSet) Parse(arguments []string) error

Parse parses flag definitions from the argument list, which should not include the command name. Must be called after all flags in the FlagSet are defined and before flags are accessed by the program. The return value will be ErrHelp if -help was set but not defined.

func (*FlagSet) Parsed 

func (f *FlagSet) Parsed() bool

Parsed reports whether f.Parse has been called.

func (*FlagSet) PrintDefaults 

func (f *FlagSet) PrintDefaults()

PrintDefaults prints, to standard error unless configured otherwise, the default values of all defined flags in the set.

func (*FlagSet) Set 

func (f *FlagSet) Set(name, value string) error

Set sets the value of the named flag.

func (*FlagSet) SetInterspersed 

func (f *FlagSet) SetInterspersed(interspersed bool)

Whether to support interspersed option/non-option arguments.

func (*FlagSet) SetNormalizeFunc added in v0.17.0 

func (f *FlagSet) SetNormalizeFunc(n func(f *FlagSet, name string) NormalizedName)

func (*FlagSet) SetOutput 

func (f *FlagSet) SetOutput(output io.Writer)

SetOutput sets the destination for usage and error messages. If output is nil, os.Stderr is used.

func (*FlagSet) String 

func (f *FlagSet) String(name string, value string, usage string) *string

String defines a string flag with specified name, default value, and usage string. The return value is the address of a string variable that stores the value of the flag.

func (*FlagSet) StringP 

func (f *FlagSet) StringP(name, shorthand string, value string, usage string) *string

Like String, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) StringVar 

func (f *FlagSet) StringVar(p *string, name string, value string, usage string)

StringVar defines a string flag with specified name, default value, and usage string. The argument p points to a string variable in which to store the value of the flag.

func (*FlagSet) StringVarP 

func (f *FlagSet) StringVarP(p *string, name, shorthand string, value string, usage string)

Like StringVar, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) Uint 

func (f *FlagSet) Uint(name string, value uint, usage string) *uint

Uint defines a uint flag with specified name, default value, and usage string. The return value is the address of a uint variable that stores the value of the flag.

func (*FlagSet) Uint16 

func (f *FlagSet) Uint16(name string, value uint16, usage string) *uint16

Uint16 defines a uint flag with specified name, default value, and usage string. The return value is the address of a uint variable that stores the value of the flag.

func (*FlagSet) Uint16P 

func (f *FlagSet) Uint16P(name, shorthand string, value uint16, usage string) *uint16

Like Uint16, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) Uint16Var 

func (f *FlagSet) Uint16Var(p *uint16, name string, value uint16, usage string)

Uint16Var defines a uint flag with specified name, default value, and usage string. The argument p points to a uint variable in which to store the value of the flag.

func (*FlagSet) Uint16VarP 

func (f *FlagSet) Uint16VarP(p *uint16, name, shorthand string, value uint16, usage string)

Like Uint16Var, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) Uint32 

func (f *FlagSet) Uint32(name string, value uint32, usage string) *uint32

Uint32 defines a uint32 flag with specified name, default value, and usage string. The return value is the address of a uint32 variable that stores the value of the flag.

func (*FlagSet) Uint32P 

func (f *FlagSet) Uint32P(name, shorthand string, value uint32, usage string) *uint32

Like Uint32, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) Uint32Var 

func (f *FlagSet) Uint32Var(p *uint32, name string, value uint32, usage string)

Uint32Var defines a uint32 flag with specified name, default value, and usage string. The argument p points to a uint32 variable in which to store the value of the flag.

func (*FlagSet) Uint32VarP 

func (f *FlagSet) Uint32VarP(p *uint32, name, shorthand string, value uint32, usage string)

Like Uint32Var, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) Uint64 

func (f *FlagSet) Uint64(name string, value uint64, usage string) *uint64

Uint64 defines a uint64 flag with specified name, default value, and usage string. The return value is the address of a uint64 variable that stores the value of the flag.

func (*FlagSet) Uint64P 

func (f *FlagSet) Uint64P(name, shorthand string, value uint64, usage string) *uint64

Like Uint64, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) Uint64Var 

func (f *FlagSet) Uint64Var(p *uint64, name string, value uint64, usage string)

Uint64Var defines a uint64 flag with specified name, default value, and usage string. The argument p points to a uint64 variable in which to store the value of the flag.

func (*FlagSet) Uint64VarP 

func (f *FlagSet) Uint64VarP(p *uint64, name, shorthand string, value uint64, usage string)

Like Uint64Var, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) Uint8 

func (f *FlagSet) Uint8(name string, value uint8, usage string) *uint8

Uint8 defines a uint8 flag with specified name, default value, and usage string. The return value is the address of a uint8 variable that stores the value of the flag.

func (*FlagSet) Uint8P 

func (f *FlagSet) Uint8P(name, shorthand string, value uint8, usage string) *uint8

Like Uint8, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) Uint8Var 

func (f *FlagSet) Uint8Var(p *uint8, name string, value uint8, usage string)

Uint8Var defines a uint8 flag with specified name, default value, and usage string. The argument p points to a uint8 variable in which to store the value of the flag.

func (*FlagSet) Uint8VarP 

func (f *FlagSet) Uint8VarP(p *uint8, name, shorthand string, value uint8, usage string)

Like Uint8Var, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) UintP 

func (f *FlagSet) UintP(name, shorthand string, value uint, usage string) *uint

Like Uint, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) UintVar 

func (f *FlagSet) UintVar(p *uint, name string, value uint, usage string)

UintVar defines a uint flag with specified name, default value, and usage string. The argument p points to a uint variable in which to store the value of the flag.

func (*FlagSet) UintVarP 

func (f *FlagSet) UintVarP(p *uint, name, shorthand string, value uint, usage string)

Like UintVar, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) Var 

func (f *FlagSet) Var(value Value, name string, usage string)

Var defines a flag with the specified name and usage string. The type and value of the flag are represented by the first argument, of type Value, which typically holds a user-defined implementation of Value. For instance, the caller could create a flag that turns a comma-separated string into a slice of strings by giving the slice the methods of Value; in particular, Set would decompose the comma-separated string into the slice.

func (*FlagSet) VarP 

func (f *FlagSet) VarP(value Value, name, shorthand, usage string)

Like Var, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) Visit 

func (f *FlagSet) Visit(fn func(*Flag))

Visit visits the flags in lexicographical order, calling fn for each. It visits only those flags that have been set.

func (*FlagSet) VisitAll 

func (f *FlagSet) VisitAll(fn func(*Flag))

VisitAll visits the flags in lexicographical order, calling fn for each. It visits all flags, even those not set.

type NormalizedName added in v0.17.0 

type NormalizedName string

NormalizedName is a flag name that has been normalized according to rules for the FlagSet (e.g. making '-' and '_' equivalent).

type Value 

type Value interface {
	String() string
	Set(string) error
	Type() string
}

Value is the interface to the dynamic value stored in a flag. (The default value is represented as a string.)

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