flag

package
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 Go to latest Published: Nov 1, 2016 License: GPL-3.0, BSD-3-Clause Imports: 13 Imported by: 0

README

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Description

flag is a drop-in replacement for Go's flag package, implementing POSIX/GNU-style --flags.

flag 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.

flag is available under the same style of BSD license as the Go language, which can be found in the LICENSE file.

Installation

flag is available using the standard go get command.

Install by running:

go get github.com/spf13/flag

Run tests by running:

go test github.com/spf13/flag

Usage

flag is a drop-in replacement of Go's native flag package. If you import flag under the name "flag" then all code should continue to function with no changes.

import flag "github.com/spf13/flag"

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)

There are helpers function to get values later if you have the FlagSet but it was difficult to keep up with all of the the flag pointers in your code. If you have a flag.FlagSet with a flag called 'flagname' of type int you can use GetInt() to get the int value. But notice that 'flagname' must exist and it must be an int. GetString("flagname") will fail.

i, err := flagset.GetInt("flagname")

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 flag 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.

Setting no option default values for flags

After you create a flag it is possible to set the flag.NoOptDefVal for the given flag. Doing this changes the meaning of the flag slightly. If a flag has a NoOptDefVal and the flag is set on the command line without an option the flag will be set to the NoOptDefVal. For example given:

var ip = flag.IntP("flagname", "f", 1234, "help message")
flag.Lookup("flagname").NoOptDefVal = "4321"

Would result in something like

Parsed Arguments Resulting Value
--flagname=1357 ip=1357
--flagname ip=4321
[nothing] ip=1234

Command line flag syntax

--flag    // boolean flags, or flags with no option default values
--flag x  // only on flags without a default value
--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 or a flag with a default value

// boolean or flags where the 'no option default value' is set
-f
-f=true
-abc
but
-b true is INVALID

// non-boolean and flags without a 'no option default value'
-n 1234
-n=1234
-n1234

// mixed
-abcs "hello"
-absd="hello"
-abcs1234

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

myFlagSet.SetNormalizeFunc(wordSepNormalizeFunc)

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

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

myFlagSet.SetNormalizeFunc(aliasNormalizeFunc)

Deprecating a flag or its shorthand

It is possible to deprecate a flag, or just its shorthand. Deprecating a flag/shorthand hides it from help text and prints a usage message when the deprecated flag/shorthand is used.

Example #1: You want to deprecate a flag named "badflag" as well as inform the users what flag they should use instead.

// deprecate a flag by specifying its name and a usage message
flags.MarkDeprecated("badflag", "please use --good-flag instead")

This hides "badflag" from help text, and prints Flag --badflag has been deprecated, please use --good-flag instead when "badflag" is used.

Example #2: You want to keep a flag name "noshorthandflag" but deprecate its shortname "n".

// deprecate a flag shorthand by specifying its flag name and a usage message
flags.MarkShorthandDeprecated("noshorthandflag", "please use --noshorthandflag only")

This hides the shortname "n" from help text, and prints Flag shorthand -n has been deprecated, please use --noshorthandflag only when the shorthand "n" is used.

Note that usage message is essential here, and it should not be empty.

Hidden flags

It is possible to mark a flag as hidden, meaning it will still function as normal, however will not show up in usage/help text.

Example: You have a flag named "secretFlag" that you need for internal use only and don't want it showing up in help text, or for its usage text to be available.

// hide a flag by specifying its name
flags.MarkHidden("secretFlag")

More info

You can see the full reference documentation of the flag 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/flag after installation.

Documentation

Overview

Package flag is a drop-in replacement for Go's flag package, implementing POSIX/GNU-style --flags.

flag 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:

flag is a drop-in replacement of Go's native flag package. If you import flag under the name "flag" then all code should continue to function with no changes. 

import flag "github.com/ogier/flag"

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 flag 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"

	"github.com/EricLagergren/go-coreutils/internal/flag"
)

// 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 Bugs = func() {
	fmt.Printf(`
Report %s bugs to eric@ericlagergren.com
Go coreutils home page: <https://www.github.com/EricLagergren/go-coreutils/>
`, Program)
}
View Source 
var CommandLine = NewFlagSet(Program, ExitOnError)

CommandLine is the default set of command-line flags, parsed from os.Args.

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

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

View Source 
var ErrVersion = errors.New("flag: version requested")

ErrVersion is the error returned if the flag -version is invoked but no such flag is defined.

View Source 
var ProgVersion = "0.1"
View Source 
var Program = TrimDotSlash(os.Args[0])

Program is the normalized name of the running binary. (I.e., os.Args[0].)

View Source 
var Usage = func() {
	fmt.Printf("Usage: %s [OPTION]... [FILE]\n\n", Program)
	PrintDefaults()
	Bugs()
}

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. By default it prints a simple header and calls PrintDefaults; for details about the format of the output and how to control it, see the documentation for PrintDefaults.

View Source 
var Version = func() {
	fmt.Fprintf(os.Stdout, `%s (Go coreutils) %s
Copyright (c) 2016 Eric Lagergren
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
`, Program, ProgVersion)
	os.Exit(0)
}

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

BoolP is 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)

BoolVarP is like BoolVar, but accepts a shorthand letter that can be used after a single dash.

func Count 

func Count(name string, usage string) *int

Count like Count only the flag is placed on the CommandLine isntead of a given flag set

func CountP 

func CountP(name, shorthand string, usage string) *int

CountP is like Count only takes a shorthand for the flag name.

func CountVar 

func CountVar(p *int, name string, usage string)

CountVar like CountVar only the flag is placed on the CommandLine instead of a given flag set

func CountVarP 

func CountVarP(p *int, name, shorthand string, usage string)

CountVarP is like CountVar only take a shorthand for the flag name.

func DBE 

func DBE()

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

DurationP is 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)

DurationVarP is 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

Float32P is 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)

Float32VarP is 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

Float64P is 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)

Float64VarP is 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

IPMaskP is 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)

IPMaskVarP is like IPMaskVar, but accepts a shorthand letter that can be used after a single dash.

func IPNet 

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

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

func IPNetP 

func IPNetP(name, shorthand string, value net.IPNet, usage string) *net.IPNet

IPNetP is like IPNet, but accepts a shorthand letter that can be used after a single dash.

func IPNetVar 

func IPNetVar(p *net.IPNet, name string, value net.IPNet, usage string)

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

func IPNetVarP 

func IPNetVarP(p *net.IPNet, name, shorthand string, value net.IPNet, usage string)

IPNetVarP is like IPNetVar, 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

IPP is 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)

IPVarP is 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

Int32P is 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)

Int32VarP is 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

Int64P is 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)

Int64VarP is 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

Int8P is 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)

Int8VarP is 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

IntP is like Int, but accepts a shorthand letter that can be used after a single dash.

func IntSlice 

func IntSlice(name string, value []int, usage string) *[]int

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

func IntSliceP 

func IntSliceP(name, shorthand string, value []int, usage string) *[]int

IntSliceP is like IntSlice, but accepts a shorthand letter that can be used after a single dash.

func IntSliceVar 

func IntSliceVar(p *[]int, name string, value []int, usage string)

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

func IntSliceVarP 

func IntSliceVarP(p *[]int, name, shorthand string, value []int, usage string)

IntSliceVarP is like IntSliceVar, 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)

IntVarP is 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

ParseIPv4Mask 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)

SetInterspersed sets 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

StringP is like String, but accepts a shorthand letter that can be used after a single dash.

func StringSlice 

func StringSlice(name string, value []string, usage string) *[]string

StringSlice 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 StringSliceP 

func StringSliceP(name, shorthand string, value []string, usage string) *[]string

StringSliceP is like StringSlice, but accepts a shorthand letter that can be used after a single dash.

func StringSliceVar 

func StringSliceVar(p *[]string, name string, value []string, usage string)

StringSliceVar 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 StringSliceVarP 

func StringSliceVarP(p *[]string, name, shorthand string, value []string, usage string)

StringSliceVarP is like StringSliceVar, 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)

StringVarP is like StringVar, but accepts a shorthand letter that can be used after a single dash.

func TrimDotSlash 

func TrimDotSlash(s string) string

TrimDotSlash removes a prefixed "./" from the given string.

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

Uint16P is 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)

Uint16VarP is 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

Uint32P is 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)

Uint32VarP is 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

Uint64P is 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)

Uint64VarP is 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

Uint8P is 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)

Uint8VarP is 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

UintP is 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)

UintVarP is like UintVar, but accepts a shorthand letter that can be used after a single dash.

func UnquoteUsage 

func UnquoteUsage(flag *Flag) (name string, usage string)

UnquoteUsage extracts a back-quoted name from the usage string for a flag and returns it and the un-quoted usage. Given "a `name` to show" it returns ("name", "a name to show"). If there are no back quotes, the name is an educated guess of the type of the flag's value, or the empty string if the flag is boolean.

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)

VarP is 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 will return an err from Parse() if an error is found
	ContinueOnError ErrorHandling = iota
	// ExitOnError will call os.Exit(2) if an error is found when parsing
	ExitOnError
	// PanicOnError will panic() if an error is found when parsing flags
	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)
	NoOptDefVal string // default value (as text); if the flag is on the command line without any options
}

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.

func PFlagFromGoFlag 

func PFlagFromGoFlag(goflag *goflag.Flag) *Flag

PFlagFromGoFlag will return a *flag.Flag given a *flag.Flag If the *flag.Flag.Name was a single character (ex: `v`) it will be accessiblei with both `-v` and `--v` in flags. If the golang flag was more than a single character (ex: `verbose`) it will only be accessible via `--verbose`

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()
	Version 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)

AddFlag will add the flag to the FlagSet

func (*FlagSet) AddFlagSet 

func (f *FlagSet) AddFlagSet(newSet *FlagSet)

AddFlagSet adds one FlagSet to another. If a flag is already present in f the flag from newSet will be ignored

func (*FlagSet) AddGoFlag 

func (f *FlagSet) AddGoFlag(goflag *goflag.Flag)

AddGoFlag will add the given *flag.Flag to the flag.FlagSet

func (*FlagSet) AddGoFlagSet 

func (f *FlagSet) AddGoFlagSet(newSet *goflag.FlagSet)

AddGoFlagSet will add the given *flag.FlagSet to the flag.FlagSet

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) ArgsLenAtDash 

func (f *FlagSet) ArgsLenAtDash() int

ArgsLenAtDash will return the length of f.Args at the moment when a -- was found during arg parsing. This allows your program to know which args were before the -- and which came after.

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

BoolP is 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)

BoolVarP is like BoolVar, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) Changed 

func (f *FlagSet) Changed(name string) bool

Changed returns true if the flag was explicitly set during Parse() and false otherwise

func (*FlagSet) Count 

func (f *FlagSet) Count(name string, usage string) *int

Count defines a count 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. A count flag will add 1 to its value evey time it is found on the command line

func (*FlagSet) CountP 

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

CountP is like Count only takes a shorthand for the flag name.

func (*FlagSet) CountVar 

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

CountVar defines a count 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. A count flag will add 1 to its value evey time it is found on the command line

func (*FlagSet) CountVarP 

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

CountVarP is like CountVar only take a shorthand for the flag name.

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

DurationP is 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)

DurationVarP is like DurationVar, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) FlagUsages 

func (f *FlagSet) FlagUsages() string

FlagUsages Returns a string containing the usage information for all flags in the FlagSet

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

Float32P is 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)

Float32VarP is 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

Float64P is 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)

Float64VarP is like Float64Var, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) GetBool 

func (f *FlagSet) GetBool(name string) (bool, error)

GetBool return the bool value of a flag with the given name

func (*FlagSet) GetCount 

func (f *FlagSet) GetCount(name string) (int, error)

GetCount return the int value of a flag with the given name

func (*FlagSet) GetDuration 

func (f *FlagSet) GetDuration(name string) (time.Duration, error)

GetDuration return the duration value of a flag with the given name

func (*FlagSet) GetFloat32 

func (f *FlagSet) GetFloat32(name string) (float32, error)

GetFloat32 return the float32 value of a flag with the given name

func (*FlagSet) GetFloat64 

func (f *FlagSet) GetFloat64(name string) (float64, error)

GetFloat64 return the float64 value of a flag with the given name

func (*FlagSet) GetIP 

func (f *FlagSet) GetIP(name string) (net.IP, error)

GetIP return the net.IP value of a flag with the given name

func (*FlagSet) GetIPNet 

func (f *FlagSet) GetIPNet(name string) (net.IPNet, error)

GetIPNet return the net.IPNet value of a flag with the given name

func (*FlagSet) GetIPv4Mask 

func (f *FlagSet) GetIPv4Mask(name string) (net.IPMask, error)

GetIPv4Mask return the net.IPv4Mask value of a flag with the given name

func (*FlagSet) GetInt 

func (f *FlagSet) GetInt(name string) (int, error)

GetInt return the int value of a flag with the given name

func (*FlagSet) GetInt32 

func (f *FlagSet) GetInt32(name string) (int32, error)

GetInt32 return the int32 value of a flag with the given name

func (*FlagSet) GetInt64 

func (f *FlagSet) GetInt64(name string) (int64, error)

GetInt64 return the int64 value of a flag with the given name

func (*FlagSet) GetInt8 

func (f *FlagSet) GetInt8(name string) (int8, error)

GetInt8 return the int8 value of a flag with the given name

func (*FlagSet) GetIntSlice 

func (f *FlagSet) GetIntSlice(name string) ([]int, error)

GetIntSlice return the []int value of a flag with the given name

func (*FlagSet) GetNormalizeFunc 

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

GetNormalizeFunc returns the previously set NormalizeFunc of a function which does no translation, if not set previously.

func (*FlagSet) GetString 

func (f *FlagSet) GetString(name string) (string, error)

GetString return the string value of a flag with the given name

func (*FlagSet) GetStringSlice 

func (f *FlagSet) GetStringSlice(name string) ([]string, error)

GetStringSlice return the []string value of a flag with the given name

func (*FlagSet) GetUint 

func (f *FlagSet) GetUint(name string) (uint, error)

GetUint return the uint value of a flag with the given name

func (*FlagSet) GetUint16 

func (f *FlagSet) GetUint16(name string) (uint16, error)

GetUint16 return the uint16 value of a flag with the given name

func (*FlagSet) GetUint32 

func (f *FlagSet) GetUint32(name string) (uint32, error)

GetUint32 return the uint32 value of a flag with the given name

func (*FlagSet) GetUint64 

func (f *FlagSet) GetUint64(name string) (uint64, error)

GetUint64 return the uint64 value of a flag with the given name

func (*FlagSet) GetUint8 

func (f *FlagSet) GetUint8(name string) (uint8, error)

GetUint8 return the uint8 value of a flag with the given name

func (*FlagSet) HasFlags 

func (f *FlagSet) HasFlags() bool

HasFlags returns a bool to indicate if the FlagSet has any flags definied.

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

IPMaskP is 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)

IPMaskVarP is like IPMaskVar, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) IPNet 

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

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

func (*FlagSet) IPNetP 

func (f *FlagSet) IPNetP(name, shorthand string, value net.IPNet, usage string) *net.IPNet

IPNetP is like IPNet, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) IPNetVar 

func (f *FlagSet) IPNetVar(p *net.IPNet, name string, value net.IPNet, usage string)

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

func (*FlagSet) IPNetVarP 

func (f *FlagSet) IPNetVarP(p *net.IPNet, name, shorthand string, value net.IPNet, usage string)

IPNetVarP is like IPNetVar, 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

IPP is 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)

IPVarP is 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

Int32P is 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)

Int32VarP is 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

Int64P is 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)

Int64VarP is 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

Int8P is 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)

Int8VarP is 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

IntP is like Int, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) IntSlice 

func (f *FlagSet) IntSlice(name string, value []int, usage string) *[]int

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

func (*FlagSet) IntSliceP 

func (f *FlagSet) IntSliceP(name, shorthand string, value []int, usage string) *[]int

IntSliceP is like IntSlice, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) IntSliceVar 

func (f *FlagSet) IntSliceVar(p *[]int, name string, value []int, usage string)

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

func (*FlagSet) IntSliceVarP 

func (f *FlagSet) IntSliceVarP(p *[]int, name, shorthand string, value []int, usage string)

IntSliceVarP is like IntSliceVar, 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)

IntVarP is 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) 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)

SetInterspersed sets whether to support interspersed option/non-option arguments.

func (*FlagSet) SetNormalizeFunc 

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

SetNormalizeFunc allows you to add a function which can translate flag names. Flags added to the FlagSet will be translated and then when anything tries to look up the flag that will also be translated. So it would be possible to create a flag named "getURL" and have it translated to "geturl". A user could then pass "--getUrl" which may also be translated to "geturl" and everything will work.

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

StringP is like String, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) StringSlice 

func (f *FlagSet) StringSlice(name string, value []string, usage string) *[]string

StringSlice 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) StringSliceP 

func (f *FlagSet) StringSliceP(name, shorthand string, value []string, usage string) *[]string

StringSliceP is like StringSlice, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) StringSliceVar 

func (f *FlagSet) StringSliceVar(p *[]string, name string, value []string, usage string)

StringSliceVar 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) StringSliceVarP 

func (f *FlagSet) StringSliceVarP(p *[]string, name, shorthand string, value []string, usage string)

StringSliceVarP is like StringSliceVar, 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)

StringVarP is 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

Uint16P is 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)

Uint16VarP is 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

Uint32P is 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)

Uint32VarP is 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

Uint64P is 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)

Uint64VarP is 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

Uint8P is 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)

Uint8VarP is 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

UintP is 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)

UintVarP is 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)

VarP is like Var, but accepts a shorthand letter that can be used after a single dash.

func (*FlagSet) VarPF 

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

VarPF is like VarP, but returns the flag created

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 

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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