fla9

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 Go to latest Published: Apr 11, 2024 License: MIT Imports: 14 Imported by: 11

README

Flag

fork from github.com/namsral/flag

Flag is a drop in replacement for Go's flag package with the addition to parse files and environment variables.

If you support the twelve-factor app methodology, Flag complies with the third factor; "Store config in the environment".

An example:

package main

import (
	"fmt"
	flag "github.com/bingoohuang/gg/pkg/fla9"
)

func main() {
	var age int
	flag.IntVar(&age, "age", 0, "age of gopher")
	flag.Parse()
	fmt.Print("age:", age)
}

$ go run gopher.go -age 1
age: 1

Same code but using an environment variable:

$ export AGE=2
$ go run gopher.go
age: 2

Same code but using a configuration file:

$ cat > gopher.conf
age 3

$ go run gopher.go -config gopher.conf
age: 3

The following table shows how flags are translated to environment variables and configuration files:

Type Flag Environment File
int -age 2 AGE=2 age 2
bool -female FEMALE=true female true
float -length 175.5 LENGTH=175.5 length 175.5
string -name Gloria NAME=Gloria name Gloria

This package is a port of Go's flag package from the standard library with the addition of two functions ParseEnv and ParseFile.

Goals

Why?

Why not use one of the many INI, JSON or YAML parsers?

I find it best practice to have simple configuration options to control the behaviour of an applications when it starts up. Use basic types like ints, floats and strings for configuration options and store more complex data structures in the "datastore" layer.

Usage

It's intended for projects which require a simple configuration made available through command-line flags, configuration files and shell environments. It's similar to the original flag package.

Example:

import "github.com/namsral/flag"

flag.String(flag.DefaultConfigFlagname, "", "path to config file")
flag.Int("age", 24, "help message for age")

flag.Parse()

Order of precedence:

  1. Command line options
  2. Environment variables
  3. Configuration file
  4. Default values
Parsing Configuration Files

Create a configuration file:

$ cat > ./gopher.conf
# empty newlines and lines beginning with a "#" character are ignored.
name bob

# keys and values can also be separated by the "=" character
age=20

# booleans can be empty, set with 0, 1, true, false, etc
hacker

Add a "config" flag:

flag.String(flag.DefaultConfigFlagname, "", "path to config file")

Run the command:

$ go run ./gopher.go -config ./gopher.conf

The default flag name for the configuration file is "config" and can be changed by setting flag.DefaultConfigFlagname:

flag.DefaultConfigFlagname = "conf"
flag.Parse()
Parsing Environment Variables

Environment variables are parsed 1-on-1 with defined flags:

$ export AGE=44
$ go run ./gopher.go
age=44

You can also parse prefixed environment variables by setting a prefix name when creating a new empty flag set:

fs := flag.NewFlagSetWithEnvPrefix(os.Args[0], "GO", 0)
fs.Int("age", 24, "help message for age")
fs.Parse(os.Args[1:])
...
$ go export GO_AGE=33
$ go run ./gopher.go
age=33

For more examples see the examples directory in the project repository.

That's it.

Documentation

Overview

Package fla9 implements command-line flag parsing.

Usage:

Define flags using flag.String(), Bool(), Int(), etc.

This declares an integer flag, -flagname, stored in the pointer ip, with type *int. 

import "flag"
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 following the flags are available as the slice flag.Args() or individually as flag.Arg(i). The arguments are indexed from 0 through flag.NArg()-1.

Command line flag syntax: 

-flag
-flag=x
-flag x  // non-boolean flags only

One or two minus signs may be used; they are equivalent. The last form is not permitted for boolean flags because the meaning of the command 

cmd -x *

will change if there is a file called 0, false, etc. You must use the -flag=false form to turn off a boolean flag.

Flag parsing stops just before the first non-flag argument ("-" is a non-flag argument) or after the terminator "--".

Integer flags accept 1234, 0664, 0x1234 and may be negative. Boolean flags may be: 

1, 0, t, f, 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 
package main

import ()

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

Output:

Index

Examples

Constants

This section is empty.

Variables

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

CommandLine is the default set of command-line flags, parsed from os.Args. The top-level functions such as BoolVar, Arg, and so on are wrappers for the methods of CommandLine.

View Source 
var DefaultConFlagName = "fla9"

DefaultConFlagName defines the flag name of the optional config file path. Used to lookup and parse the config file when a default is set and available on disk.

View Source 
var EnvPrefix = "GG"

EnvPrefix defines a string that will be implicitly prefixed to a flag name before looking it up in the environment variables.

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

ErrHelp is the error returned if the -help or -h flag 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. It is called when an error occurs while parsing 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.

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. Arg returns an empty string if the requested element does not exist.

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 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 Count 

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

Count 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 CountVar 

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

CountVar 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 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. The flag accepts a value acceptable to time.ParseDuration.

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. The flag accepts a value acceptable to time.ParseDuration.

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 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 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 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 Int32Var 

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

Int32Var 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 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 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 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 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 ParseFileArg 

func ParseFileArg(arg string) (file string, data []byte)

ParseFileArg parse an argument which represents a string content, or @file to represents the file's content.

func Parsed 

func Parsed() bool

Parsed reports whether the command-line flags have been parsed.

func PrintDefaults 

func PrintDefaults()

PrintDefaults prints, to standard error unless configured otherwise, a usage message showing the default settings of all defined command-line flags. For an integer valued flag x, the default output has the form 

-x int
	usage-message-for-x (default 7)

The usage message will appear on a separate line for anything but a bool flag with a one-byte name. For bool flags, the type is omitted and if the flag name is one byte the usage message appears on the same line. The parenthetical default is omitted if the default is the zero value for the type. The listed type, here int, can be changed by placing a back-quoted name in the flag's usage string; the first such item in the message is taken to be a parameter name to show in the message and the back quotes are stripped from the message when displayed. For instance, given 

flag.String("I", "", "search `directory` for include files")

the output will be 

-I directory
	search directory for include files.

func Set 

func Set(name, value string) error

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

func Size 

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

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

func SizeVar 

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

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

func String 

func String(name, value, 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 StringVar 

func StringVar(p *string, name, value, 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 Strings 

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

Strings defines multiple 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 StringsVar 

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

StringsVar 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 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 Uint32Var 

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

Uint32Var 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 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 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 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 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, 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 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 FlagSet.Parse behaves if the parse fails. 

const (
	ContinueOnError ErrorHandling = iota // Return a descriptive error.
	ExitOnError                          // Call os.Exit(2).
	PanicOnError                         // Call panic with a descriptive error.
)

These constants cause FlagSet.Parse to behave as described if the parse fails.

type Flag 

type Flag struct {
	Name      string // name as it appears on command line
	ShortName string // name as it appears on command line
	Usage     string // help message
	Value     Value  // value as set
	DefValue  string // default value (as text); for usage message
	Alias     bool
}

A Flag represents the state of a flag.

Example 
package main

import (
	"fmt"

	"github.com/bingoohuang/gg/pkg/fla9"
)

func main() {
	var (
		name        string
		addr        []string
		xddr        []string
		age         int
		length      float64
		female      bool
		connections int
		v           int
		p           int
		b1          bool
		b2          bool
		b3          bool
		b4          bool
	)

	fla9.String("fla9", "testdata/test.conf", "help message")
	fla9.StringVar(&name, "name,n", "", "help message")
	fla9.IntVar(&age, "age,a", 0, "help message")
	fla9.IntVar(&connections, "c", 0, "help message")
	fla9.Float64Var(&length, "length", 0, "help message")
	fla9.BoolVar(&female, "female", false, "help message")
	fla9.CountVar(&v, "v", 0, "-v -vv -vvv")
	fla9.CountVar(&p, "p", 0, "-p -pp -ppp")
	fla9.CountVar(&p, "q", 0, "-q -qq -qqq")
	fla9.BoolVar(&b1, "b1", false, "b1")
	fla9.BoolVar(&b2, "b2", false, "b2")
	fla9.BoolVar(&b3, "b3", false, "b3")
	fla9.BoolVar(&b4, "b4", false, "b4")
	fla9.StringsVar(&addr, "addr", nil, "addr")
	fla9.StringsVar(&xddr, "xddr", nil, "xddr")

	fla9.CommandLine.Parse([]string{"-v", "-pp", "-b1", "false", "-b2", "true", "-b3", "-b4=true", "-addr=nj", "-addr=bj"})

	fmt.Println("connections:", connections)
	fmt.Println("length:", length)
	fmt.Println("age:", age)
	fmt.Println("name:", name)
	fmt.Println("female:", female)
	fmt.Println("v:", v)
	fmt.Println("p:", p)
	fmt.Println("q:", 0)
	fmt.Println("b:", b1, b2, b3, b4)
	fmt.Println("addr:", addr)
	fmt.Println("xddr:", xddr)

}

Output:

connections: 12345
length: 175.5
age: 2
name: Gloria
female: false
v: 1
p: 2
q: 0
b: false true true true
addr: [nj bj]
xddr: []

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. The zero value of a FlagSet has no name and has ContinueOnError error handling.

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 NewFlagSetWithEnvPrefix 

func NewFlagSetWithEnvPrefix(name string, prefix string, errorHandling ErrorHandling) *FlagSet

NewFlagSetWithEnvPrefix returns a new empty flag set with the specified name, environment variable prefix, and error handling property.

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. Arg returns an empty string if the requested element does not exist.

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) 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) Count 

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

Count 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) CountVar 

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

CountVar 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) 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. The flag accepts a value acceptable to time.ParseDuration.

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. The flag accepts a value acceptable to time.ParseDuration.

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) 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) 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) 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, EnvPrefix, 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) Int32Var 

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

Int32Var 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) 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) 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) 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) 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 or -h were set but not defined.

func (*FlagSet) ParseEnv 

func (f *FlagSet) ParseEnv(environ []string) error

ParseEnv parses flags from environment variables. Flags already set will be ignored.

func (*FlagSet) ParseFile 

func (f *FlagSet) ParseFile(path string, ignoreUndefinedConf bool) error

ParseFile parses flags from the file in path. Same format as commandline arguments, newlines and lines beginning with a "#" character are ignored. Flags already set will be ignored.

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 the default values of all defined command-line flags in the set. See the documentation for the global function PrintDefaults for more information.

func (*FlagSet) Set 

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

Set sets the value of the named flag.

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) Size 

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

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

func (*FlagSet) SizeVar 

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

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

func (*FlagSet) String 

func (f *FlagSet) String(name, value, 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) StringVar 

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

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

Strings 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) StringsVar 

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

StringsVar 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) 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) Uint32Var 

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

Uint32Var 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) 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) 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) 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) 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) 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 Getter 

type Getter interface {
	Value
	Get() interface{}
}

Getter is an interface that allows the contents of a Value to be retrieved. It wraps the Value interface, rather than being part of it, because it appeared after Go 1 and its compatibility rules. All Value types provided by this package satisfy the Getter interface.

type SizeFlag 

type SizeFlag struct {
	Val *uint64
}

func (*SizeFlag) Set 

func (i *SizeFlag) Set(value string) (err error)

func (*SizeFlag) String 

func (i *SizeFlag) String() string

type StringBool 

type StringBool struct {
	Val    string
	Exists bool
}

func (*StringBool) Get 

func (i *StringBool) Get() interface{}

func (*StringBool) Set 

func (i *StringBool) Set(value string) error

func (*StringBool) SetExists 

func (i *StringBool) SetExists(b bool)

func (*StringBool) String 

func (i *StringBool) String() string

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.)

If a Value has an IsBoolFlag() bool method returning true, the command-line parser makes -name equivalent to -name=true rather than using the next command-line argument.

Set is called once, in command line order, for each flag present.

func NewSizeFlag 

func NewSizeFlag(up *uint64, val string) Value

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