pflag

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Version: v0.1.2 Latest Latest
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Published: May 30, 2014 License: BSD-3-Clause, MIT Imports: 9 Imported by: 0

README

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.

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/ogier/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)
}

// 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 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 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 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 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 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 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 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 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)
}

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) 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) HasFlags

func (f *FlagSet) HasFlags() bool

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) 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) 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) 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) 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) 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) 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 Value

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

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

Source Files

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