kingpin

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 Go to latest Published: May 22, 2015 License: MIT Imports: 18 Imported by: 35

README

Kingpin - A Go (golang) command line and flag parser Build Status

Overview

Kingpin is a fluent-style, type-safe command-line parser. It supports flags, nested commands, and positional arguments.

Install it with:

$ go get gopkg.in/alecthomas/kingpin.v2

It looks like this:

var (
  verbose = kingpin.Flag("verbose", "Verbose mode.").Short('v').Bool()
  name    = kingpin.Arg("name", "Name of user.").Required().String()
)

func main() {
  kingpin.Parse()
  fmt.Printf("%v, %s\n", *verbose, *name)
}

More examples are available.

Second to parsing, providing the user with useful help is probably the most important thing a command-line parser does. Kingpin tries to provide detailed contextual help if --help is encountered at any point in the command line (excluding after --).

Features

  • Help output that isn't as ugly as sin.
  • Fully customisable help, via Go templates.
  • Parsed, type-safe flags (kingpin.Flag("f", "help").Int())
  • Parsed, type-safe positional arguments (kingpin.Arg("a", "help").Int()).
  • Support for required flags and required positional arguments (kingpin.Flag("f", "").Required().Int()).
  • Callbacks per command, flag and argument (kingpin.Command("c", "").Action(myAction)).
  • POSIX-style short flag combining (-a -b -> -ab).
  • Short-flag+parameter combining (-a parm -> -aparm).
  • Read command-line from files (@<file>).

User-visible changes between v1 and v2

Flags can be used at any point after their definition.

Flags can be specified at any point after their definition, not just immediately after their associated command. From the chat example below, the following used to be required:

$ chat --server=chat.server.com:8080 post --image=~/Downloads/owls.jpg pics

But the following will now work:

$ chat post --server=chat.server.com:8080 --image=~/Downloads/owls.jpg pics
Short flags can be combined with their parameters

Previously, if a short flag was used, any argument to that flag would have to be separated by a space. That is no longer the case.

API changes between v1 and v2

  • ParseWithFileExpansion() is gone. The new parser directly supports expanding @<file>.
  • Added FatalUsage() and FatalUsageContext() for displaying an error + usage and terminating.
  • Dispatch() renamed to Action().
  • Added ParseContext() for parsing a command line into its intermediate context form without executing.
  • Added Terminate() function to override the termination function.
  • Added UsageForContextWithTemplate() for printing usage via a custom template.
  • Added UsageTemplate() for overriding the default template to use. Two templates are included:
    1. UsageTemplate - default template.
    2. CompactUsageTemplate - compact command template for larger applications.

Versions

Kingpin uses gopkg.in for versioning.

The current stable version is gopkg.in/alecthomas/kingpin.v2. The previous version, gopkg.in/alecthomas/kingpin.v1, is deprecated and in maintenance mode.

V2 is the current stable version

Installation:

$ go get gopkg.in/alecthomas/kingpin.v2
V1 is the OLD stable version

Installation:

$ go get gopkg.in/alecthomas/kingpin.v1

Change History

  • 2015-05-22 -- Stable v2.0.0 release.

    • Initial stable release of v2.0.0.
    • Fully supports interspersed flags, commands and arguments.
    • Flags can be present at any point after their logical definition.
    • Application.Parse() terminates if commands are present and a command is not parsed.
    • Dispatch() -> Action().
    • Actions are dispatched after all values are populated.
    • Override termination function (defaults to os.Exit).
    • Override output stream (defaults to os.Stderr).
    • Templatised usage help, with default and compact templates.
    • Make error/usage functions more consistent.
    • Support argument expansion from files by default (with @).
    • Fully public data model is available via .Model().
    • Parser has been completely refactored.
    • Parsing and execution has been split into distinct stages.
    • Use go generate to generate repeated flags.
    • Support combined short-flag+argument: -fARG.

  • 2015-01-23 -- Stable v1.3.4 release.

    • Support "--" for separating flags from positional arguments.
    • Support loading flags from files (ParseWithFileExpansion()). Use @FILE as an argument.
    • Add post-app and post-cmd validation hooks. This allows arbitrary validation to be added.
    • A bunch of improvements to help usage and formatting.
    • Support arbitrarily nested sub-commands.

  • 2014-07-08 -- Stable v1.2.0 release.

    • Pass any value through to Strings() when final argument. Allows for values that look like flags to be processed.
    • Allow --help to be used with commands.
    • Support Hidden() flags.
    • Parser for units.Base2Bytes type. Allows for flags like --ram=512MB or --ram=1GB.
    • Add an Enum() value, allowing only one of a set of values to be selected. eg. Flag(...).Enum("debug", "info", "warning").

  • 2014-06-27 -- Stable v1.1.0 release.

    • Bug fixes.
    • Always return an error (rather than panicing) when misconfigured.
    • OpenFile(flag, perm) value type added, for finer control over opening files.
    • Significantly improved usage formatting.

  • 2014-06-19 -- Stable v1.0.0 release.

    • Support cumulative positional arguments.
    • Return error rather than panic when there are fatal errors not caught by the type system. eg. when a default value is invalid.
    • Use gokpg.in.

  • 2014-06-10 -- Place-holder streamlining.

    • Renamed MetaVar to PlaceHolder.
    • Removed MetaVarFromDefault. Kingpin now uses heuristics to determine what to display.

Examples

Simple Example

Kingpin can be used for simple flag+arg applications like so:

$ ping --help
usage: ping [<flags>] <ip> [<count>]

Flags:
  --debug            Enable debug mode.
  --help             Show help.
  -t, --timeout=5s   Timeout waiting for ping.

Args:
  <ip>        IP address to ping.
  [<count>]   Number of packets to send
$ ping 1.2.3.4 5
Would ping: 1.2.3.4 with timeout 5s and count 0

From the following source:

package main

import (
  "fmt"

  "gopkg.in/alecthomas/kingpin.v2"
)

var (
  debug   = kingpin.Flag("debug", "Enable debug mode.").Bool()
  timeout = kingpin.Flag("timeout", "Timeout waiting for ping.").Default("5s").OverrideDefaultFromEnvar("PING_TIMEOUT").Short('t').Duration()
  ip      = kingpin.Arg("ip", "IP address to ping.").Required().IP()
  count   = kingpin.Arg("count", "Number of packets to send").Int()
)

func main() {
  kingpin.Version("0.0.1")
  kingpin.Parse()
  fmt.Printf("Would ping: %s with timeout %s and count %d", *ip, *timeout, *count)
}
Complex Example

Kingpin can also produce complex command-line applications with global flags, subcommands, and per-subcommand flags, like this:

$ chat --help
usage: chat [<flags>] <command> [<flags>] [<args> ...]

A command-line chat application.

Flags:
  --help              Show help.
  --debug             Enable debug mode.
  --server=127.0.0.1  Server address.

Commands:
  help [<command>]
    Show help for a command.

  register <nick> <name>
    Register a new user.

  post [<flags>] <channel> [<text>]
    Post a message to a channel.

$ chat help post
usage: chat [<flags>] post [<flags>] <channel> [<text>]

Post a message to a channel.

Flags:
  --image=IMAGE  Image to post.

Args:
  <channel>  Channel to post to.
  [<text>]   Text to post.

$ chat post --image=~/Downloads/owls.jpg pics
...

From this code:

package main

import (
  "os"
  "strings"
  "gopkg.in/alecthomas/kingpin.v2"
)

var (
  app      = kingpin.New("chat", "A command-line chat application.")
  debug    = app.Flag("debug", "Enable debug mode.").Bool()
  serverIP = app.Flag("server", "Server address.").Default("127.0.0.1").IP()

  register     = app.Command("register", "Register a new user.")
  registerNick = register.Arg("nick", "Nickname for user.").Required().String()
  registerName = register.Arg("name", "Name of user.").Required().String()

  post        = app.Command("post", "Post a message to a channel.")
  postImage   = post.Flag("image", "Image to post.").File()
  postChannel = post.Arg("channel", "Channel to post to.").Required().String()
  postText    = post.Arg("text", "Text to post.").Strings()
)

func main() {
  switch kingpin.MustParse(app.Parse(os.Args[1:])) {
  // Register user
  case register.FullCommand():
    println(*registerNick)

  // Post message
  case post.FullCommand():
    if *postImage != nil {
    }
    text := strings.Join(*postText, " ")
    println("Post:", text)
  }
}

Reference Documentation

Displaying errors and usage information

Kingpin exports a set of functions to provide consistent errors and usage information to the user.

Error messages look something like this:

<app>: error: <message>

The functions on Application are:

Function Purpose
Errorf(w, format, args) Display a printf formatted error to the user.
Fatalf(w, format, args) As with Errorf, but also call the termination handler.
FatalUsage(w, format, args) As with Fatalf, but also print contextual usage information.
FatalUsageContext(w, context, format, args) As with Fatalf, but also print contextual usage information from a ParseContext.
FatalIfError(w, err, format, args) Conditionally print an error prefixed with format+args, then call the termination handler

There are equivalent global functions in the kingpin namespace for the default kingpin.CommandLine instance.

Sub-commands

Kingpin supports nested sub-commands, with separate flag and positional arguments per sub-command. Note that positional arguments may only occur after sub-commands.

For example:

var (
  deleteCommand     = kingpin.Command("delete", "Delete an object.")
  deleteUserCommand = deleteCommand.Command("user", "Delete a user.")
  deleteUserUIDFlag = deleteUserCommand.Flag("uid", "Delete user by UID rather than username.")
  deleteUserUsername = deleteUserCommand.Arg("username", "Username to delete.")
  deletePostCommand = deleteCommand.Command("post", "Delete a post.")
)

func main() {
  switch kingpin.Parse() {
  case "delete user":
  case "delete post":
  }
}
Custom Parsers

Kingpin supports both flag and positional argument parsers for converting to Go types. For example, some included parsers are Int(), Float(), Duration() and ExistingFile().

Parsers conform to Go's flag.Value interface, so any existing implementations will work.

For example, a parser for accumulating HTTP header values might look like this:

type HTTPHeaderValue http.Header

func (h *HTTPHeaderValue) Set(value string) error {
  parts := strings.SplitN(value, ":", 2)
  if len(parts) != 2 {
    return fmt.Errorf("expected HEADER:VALUE got '%s'", value)
  }
  (*http.Header)(h).Add(parts[0], parts[1])
  return nil
}

func (h *HTTPHeaderValue) String() string {
  return ""
}

As a convenience, I would recommend something like this:

func HTTPHeader(s Settings) (target *http.Header) {
  target = new(http.Header)
  s.SetValue((*HTTPHeaderValue)(target))
  return
}

You would use it like so:

headers = HTTPHeader(kingpin.Flag("header", "Add a HTTP header to the request.").Short('H'))
Default Values

The default value is the zero value for a type. This can be overridden with the Default(value) function on flags and arguments. This function accepts a string, which is parsed by the value itself, so it must be compliant with the format expected.

Place-holders in Help

The place-holder value for a flag is the value used in the help to describe the value of a non-boolean flag.

The value provided to PlaceHolder() is used if provided, then the value provided by Default() if provided, then finally the capitalised flag name is used.

Here are some examples of flags with various permutations:

--name=NAME           // Flag(...).String()
--name="Harry"        // Flag(...).Default("Harry").String()
--name=FULL-NAME      // flag(...).PlaceHolder("FULL-NAME").Default("Harry").String()
Consuming all remaining arguments

A common command-line idiom is to use all remaining arguments for some purpose. eg. The following command accepts an arbitrary number of IP addresses as positional arguments:

./cmd ping 10.1.1.1 192.168.1.1

Kingpin supports this by having Value provide a IsCumulative() bool function. If this function exists and returns true, the value parser will be called repeatedly for every remaining argument.

Examples of this are the Strings() and StringMap() values.

To implement the above example we might do something like this:

type ipList []net.IP

func (i *ipList) Set(value string) error {
  if ip := net.ParseIP(value); ip == nil {
    return fmt.Errorf("'%s' is not an IP address", value)
  } else {
    *i = append(*i, ip)
    return nil
  }
}

func (i *ipList) String() string {
  return ""
}

func (i *ipList) IsCumulative() bool {
  return true
}

func IPList(s Settings) (target *[]net.IP) {
  target = new([]net.IP)
  s.SetValue((*ipList)(target))
  return
}

And use it like so:

ips := IPList(kingpin.Arg("ips", "IP addresses to ping."))
Custom help

Kingpin v2 supports templatised help using the text/template library (actually, a fork).

You can specify the template to use with the Application.UsageTemplate() function.

There are two included templates: kingpin.UsageTemplate is the default, and kingpin.CompactUsageTemplate provides a more compact representation for commands, for more complex command line structures.

This is the default template as of 22 May 2015:

{{define "FormatCommand"}}\
{{if .FlagSummary}} {{.FlagSummary}}{{end}}\
{{range .Args}} {{if not .Required}}[{{end}}<{{.Name}}>{{if .Value|IsCumulative}}...{{end}}{{if not .Required}}]{{end}}{{end}}\
{{end}}\
{{define "FormatCommands"}}\
{{range .FlattenedCommands}}\
  {{.FullCommand}}{{template "FormatCommand" .}}
{{.Help|Wrap 4}}
{{end}}\
{{end}}\
{{define "FormatUsage"}}\
{{template "FormatCommand" .}}{{if .Commands}} <command> [<args> ...]{{end}}
{{if .Help}}
{{.Help|Wrap 0}}\
{{end}}\
{{end}}\
{{if .Context.SelectedCommand}}\
usage: {{.App.Name}} {{.Context.SelectedCommand}}{{template "FormatUsage" .Context.SelectedCommand}}
{{else}}\
usage: {{.App.Name}}{{template "FormatUsage" .App}}
{{end}}\
{{if .Context.Flags}}\
Flags:
{{.Context.Flags|FlagsToTwoColumns|FormatTwoColumns}}
{{end}}\
{{if .Context.Args}}\
Args:
{{.Context.Args|ArgsToTwoColumns|FormatTwoColumns}}
{{end}}\
{{if .Context.SelectedCommand}}\
Subcommands:
{{if .Context.SelectedCommand.Commands}}\
{{template "FormatCommands" .Context.SelectedCommand}}
{{end}}\
{{else if .App.Commands}}\
Commands:
{{template "FormatCommands" .App}}
{{end}}\

See the above templates for examples of usage, and the the function UsageForContextWithTemplate() method for details on the context.

Documentation

Overview

Package kingpin provides command line interfaces like this: 

$ chat
usage: chat [<flags>] <command> [<flags>] [<args> ...]

Flags:
  --debug              enable debug mode
  --help               Show help.
  --server=127.0.0.1   server address

Commands:
  help <command>
    Show help for a command.

  post [<flags>] <channel>
    Post a message to a channel.

  register <nick> <name>
    Register a new user.

$ chat help post
usage: chat [<flags>] post [<flags>] <channel> [<text>]

Post a message to a channel.

Flags:
  --image=IMAGE   image to post

Args:
  <channel>   channel to post to
  [<text>]    text to post
$ chat post --image=~/Downloads/owls.jpg pics

From code like this: 

package main

import "gopkg.in/alecthomas/kingpin.v1"

var (
  debug    = kingpin.Flag("debug", "enable debug mode").Default("false").Bool()
  serverIP = kingpin.Flag("server", "server address").Default("127.0.0.1").IP()

  register     = kingpin.Command("register", "Register a new user.")
  registerNick = register.Arg("nick", "nickname for user").Required().String()
  registerName = register.Arg("name", "name of user").Required().String()

  post        = kingpin.Command("post", "Post a message to a channel.")
  postImage   = post.Flag("image", "image to post").ExistingFile()
  postChannel = post.Arg("channel", "channel to post to").Required().String()
  postText    = post.Arg("text", "text to post").String()
)

func main() {
  switch kingpin.Parse() {
  // Register user
  case "register":
    println(*registerNick)

  // Post message
  case "post":
    if *postImage != nil {
    }
    if *postText != "" {
    }
  }
}

Index

Examples

Constants

This section is empty.

Variables

View Source 
var (
	// CommandLine is the default Kingpin parser.
	CommandLine = New(filepath.Base(os.Args[0]), "")
)
View Source 
var CompactUsageTemplate = `` /* 1202-byte string literal not displayed */

Usage template with compactly formatted commands.

View Source 
var (
	ErrCommandNotSpecified = fmt.Errorf("command not specified")
)
View Source 
var (
	TokenEOLMarker = Token{-1, TokenEOL, ""}
)
View Source 
var UsageTemplate = `` /* 1129-byte string literal not displayed */

Default usage template.

Functions

func Errorf 

func Errorf(format string, args ...interface{})

Errorf prints an error message to stderr.

func ExpandArgsFromFile 

func ExpandArgsFromFile(filename string) (out []string, err error)

Expand arguments from a file. Lines starting with # will be treated as comments.

func FatalIfError 

func FatalIfError(err error, prefix string)

FatalIfError prints an error and exits if err is not nil. The error is printed with the given prefix.

func FatalUsage 

func FatalUsage(format string, args ...interface{})

FatalUsage prints an error message followed by usage information, then exits with a non-zero status.

func FatalUsageContext 

func FatalUsageContext(context *ParseContext, format string, args ...interface{})

FatalUsageContext writes a printf formatted error message to stderr, then usage information for the given ParseContext, before exiting.

func Fatalf 

func Fatalf(format string, args ...interface{})

Fatalf prints an error message to stderr and exits.

func MustParse 

func MustParse(command string, err error) string

MustParse can be used with app.Parse(args) to exit with an error if parsing fails.

func Parse 

func Parse() string

Parse and return the selected command. Will call the termination handler if an error is encountered.

func Usage 

func Usage()

Usage prints usage to stderr.

func Version added in v0.3.0 

func Version(version string)

Version adds a flag for displaying the application version number.

Types

type Action 

type Action func(*ParseContext) error

Action callback executed at various stages after all values are populated. The application, commands, arguments and flags all have corresponding actions.

type Application 

type Application struct {
	Name string
	Help string
	// contains filtered or unexported fields
}

An Application contains the definitions of flags, arguments and commands for an application.

func New 

func New(name, help string) *Application

New creates a new Kingpin application instance.

func (*Application) Action 

func (a *Application) Action(action Action) *Application

Action callback to call when all values are populated and parsing is complete, but before any command, flag or argument actions.

All Action() callbacks are called in the order they are encountered on the command line.

func (Application) Arg 

func (a Application) Arg(name, help string) *ArgClause

func (*Application) Command 

func (a *Application) Command(name, help string) *CmdClause

Command adds a new top-level command.

func (*Application) Errorf added in v1.2.3 

func (a *Application) Errorf(w io.Writer, format string, args ...interface{})

Errorf prints an error message to w in the format "<appname>: error: <message>".

func (*Application) FatalIfError added in v1.2.3 

func (a *Application) FatalIfError(w io.Writer, err error, format string, args ...interface{})

FatalIfError prints an error and exits if err is not nil. The error is printed with the given formatted string, if any.

func (*Application) FatalUsage 

func (a *Application) FatalUsage(w io.Writer, format string, args ...interface{})

FatalUsage prints an error message followed by usage information, then exits with a non-zero status.

func (*Application) FatalUsageContext 

func (a *Application) FatalUsageContext(w io.Writer, context *ParseContext, format string, args ...interface{})

FatalUsageContext writes a printf formatted error message to w, then usage information for the given ParseContext, before exiting.

func (*Application) Fatalf added in v1.3.0 

func (a *Application) Fatalf(w io.Writer, format string, args ...interface{})

Fatalf writes a formatted error to w then terminates with exit status 1.

func (Application) Flag 

func (f Application) Flag(name, help string) *FlagClause

Flag defines a new flag with the given long name and help.

func (*Application) Model 

func (a *Application) Model() *ApplicationModel

func (*Application) Parse 

func (a *Application) Parse(args []string) (command string, err error)

Parse parses command-line arguments. It returns the selected command and an error. The selected command will be a space separated subcommand, if subcommands have been configured.

This will populate all flag and argument values, call all callbacks, and so on.

func (*Application) ParseContext 

func (a *Application) ParseContext(args []string) (*ParseContext, error)

ParseContext parses the given command line and returns the fully populated ParseContext.

func (*Application) Terminate 

func (a *Application) Terminate(terminate func(int)) *Application

Terminate specifies the termination handler. Defaults to os.Exit(status). If nil is passed, a no-op function will be used.

func (*Application) Usage 

func (a *Application) Usage(w io.Writer, args []string)

Usage writes application usage to w. It parses args to determine appropriate help context, such as which command to show help for.

func (*Application) UsageForContext 

func (a *Application) UsageForContext(w io.Writer, context *ParseContext) error

UsageForContext displays usage information from a ParseContext (obtained from Application.ParseContext() or Action(f) callbacks).

func (*Application) UsageForContextWithTemplate 

func (a *Application) UsageForContextWithTemplate(context *ParseContext, w io.Writer, indent int, tmpl string) error

UsageForContextWithTemplate is the base usage function. You generally don't need to use this.

func (*Application) UsageTemplate 

func (a *Application) UsageTemplate(template string) *Application

UsageTemplate specifies the text template to use when displaying usage information. The default is UsageTemplate.

func (*Application) Validate added in v1.3.3 

func (a *Application) Validate(validator ApplicationValidator) *Application

Validate sets a validation function to run when parsing.

func (*Application) Version added in v0.3.0 

func (a *Application) Version(version string) *Application

Version adds a --version flag for displaying the application version.

func (*Application) Writer 

func (a *Application) Writer(w io.Writer) *Application

Specify the writer to use for usage and errors. Defaults to os.Stderr.

type ApplicationModel 

type ApplicationModel struct {
	Name string
	Help string
	*ArgGroupModel
	*CmdGroupModel
	*FlagGroupModel
}

type ApplicationValidator added in v1.3.3 

type ApplicationValidator func(*Application) error

type ArgClause 

type ArgClause struct {
	// contains filtered or unexported fields
}

func Arg 

func Arg(name, help string) *ArgClause

Arg adds a new argument to the top-level of the default parser.

func (*ArgClause) Action 

func (a *ArgClause) Action(dispatch Action) *ArgClause

func (*ArgClause) Bool 

func (p *ArgClause) Bool() (target *bool)

Bool sets the parser to a boolean parser. Supports --no-<X> to disable the flag.

func (*ArgClause) BoolVar 

func (p *ArgClause) BoolVar(target *bool)

Bool sets the parser to a boolean parser. Supports --no-<X> to disable the flag.

func (*ArgClause) Bytes added in v1.2.0 

func (p *ArgClause) Bytes() (target *units.Base2Bytes)

Bytes parses numeric byte units. eg. 1.5KB

func (*ArgClause) BytesVar added in v1.2.0 

func (p *ArgClause) BytesVar(target *units.Base2Bytes)

BytesVar parses numeric byte units. eg. 1.5KB

func (*ArgClause) Default 

func (a *ArgClause) Default(value string) *ArgClause

Default value for this argument. It *must* be parseable by the value of the argument.

func (*ArgClause) Duration 

func (p *ArgClause) Duration() (target *time.Duration)

Duration sets the parser to a time.Duration parser.

func (*ArgClause) DurationList 

func (p *ArgClause) DurationList() (target *[]time.Duration)

DurationList accumulates time.Duration values into a slice.

func (*ArgClause) DurationListVar 

func (p *ArgClause) DurationListVar(target *[]time.Duration)

func (*ArgClause) DurationVar 

func (p *ArgClause) DurationVar(target *time.Duration)

Duration sets the parser to a time.Duration parser.

func (*ArgClause) Enum added in v1.2.0 

func (p *ArgClause) Enum(options ...string) (target *string)

Enum allows a value from a set of options.

func (*ArgClause) EnumVar added in v1.2.0 

func (p *ArgClause) EnumVar(target **string, options ...string)

EnumVar allows a value from a set of options.

func (*ArgClause) Enums added in v1.3.6 

func (p *ArgClause) Enums(options ...string) (target *[]string)

Enums allows a set of values from a set of options.

func (*ArgClause) EnumsVar added in v1.3.6 

func (p *ArgClause) EnumsVar(target *[]string, options ...string)

EnumVar allows a value from a set of options.

func (*ArgClause) ExistingDir 

func (p *ArgClause) ExistingDir() (target *string)

ExistingDir sets the parser to one that requires and returns an existing directory.

func (*ArgClause) ExistingDirVar 

func (p *ArgClause) ExistingDirVar(target *string)

ExistingDir sets the parser to one that requires and returns an existing directory.

func (*ArgClause) ExistingFile 

func (p *ArgClause) ExistingFile() (target *string)

ExistingFile sets the parser to one that requires and returns an existing file.

func (*ArgClause) ExistingFileVar 

func (p *ArgClause) ExistingFileVar(target *string)

ExistingFile sets the parser to one that requires and returns an existing file.

func (*ArgClause) File 

func (p *ArgClause) File() (target **os.File)

File returns an os.File against an existing file.

func (*ArgClause) FileVar 

func (p *ArgClause) FileVar(target **os.File)

FileVar opens an existing file.

func (*ArgClause) Float 

func (p *ArgClause) Float() (target *float64)

Float sets the parser to a float64 parser.

func (*ArgClause) FloatVar 

func (p *ArgClause) FloatVar(target *float64)

Float sets the parser to a float64 parser.

func (*ArgClause) IP 

func (p *ArgClause) IP() (target *net.IP)

IP sets the parser to a net.IP parser.

func (*ArgClause) IPList 

func (p *ArgClause) IPList() (target *[]net.IP)

IPList accumulates net.IP values into a slice.

func (*ArgClause) IPListVar 

func (p *ArgClause) IPListVar(target *[]net.IP)

func (*ArgClause) IPVar 

func (p *ArgClause) IPVar(target *net.IP)

IP sets the parser to a net.IP parser.

func (*ArgClause) Int 

func (p *ArgClause) Int() (target *int)

Int sets the parser to an int parser.

func (*ArgClause) Int64 

func (p *ArgClause) Int64() (target *int64)

Int64 parses an int64

func (*ArgClause) Int64List 

func (p *ArgClause) Int64List() (target *[]int64)

Int64List accumulates int64 values into a slice.

func (*ArgClause) Int64ListVar 

func (p *ArgClause) Int64ListVar(target *[]int64)

func (*ArgClause) Int64Var 

func (p *ArgClause) Int64Var(target *int64)

Int64 parses an int64

func (*ArgClause) IntVar 

func (p *ArgClause) IntVar(target *int)

Int sets the parser to an int parser.

func (*ArgClause) Model 

func (a *ArgClause) Model() *ArgModel

func (*ArgClause) OpenFile added in v1.1.0 

func (p *ArgClause) OpenFile(flag int, perm os.FileMode) (target **os.File)

File attempts to open a File with os.OpenFile(flag, perm).

func (*ArgClause) OpenFileVar added in v1.1.0 

func (p *ArgClause) OpenFileVar(target **os.File, flag int, perm os.FileMode)

OpenFileVar calls os.OpenFile(flag, perm)

func (*ArgClause) Required 

func (a *ArgClause) Required() *ArgClause

Required arguments must be input by the user. They can not have a Default() value provided.

func (*ArgClause) SetValue 

func (p *ArgClause) SetValue(value Value)

func (*ArgClause) String 

func (p *ArgClause) String() (target *string)

String sets the parser to a string parser.

func (*ArgClause) StringMap 

func (p *ArgClause) StringMap() (target *map[string]string)

StringMap provides key=value parsing into a map.

func (*ArgClause) StringMapVar 

func (p *ArgClause) StringMapVar(target *map[string]string)

StringMap provides key=value parsing into a map.

func (*ArgClause) StringVar 

func (p *ArgClause) StringVar(target *string)

String sets the parser to a string parser.

func (*ArgClause) Strings 

func (p *ArgClause) Strings() (target *[]string)

Strings accumulates string values into a slice.

func (*ArgClause) StringsVar 

func (p *ArgClause) StringsVar(target *[]string)

func (*ArgClause) TCP 

func (p *ArgClause) TCP() (target **net.TCPAddr)

TCP (host:port) address.

func (*ArgClause) TCPList 

func (p *ArgClause) TCPList() (target *[]*net.TCPAddr)

TCPList accumulates *net.TCPAddr values into a slice.

func (*ArgClause) TCPListVar 

func (p *ArgClause) TCPListVar(target *[]*net.TCPAddr)

func (*ArgClause) TCPVar 

func (p *ArgClause) TCPVar(target **net.TCPAddr)

TCPVar (host:port) address.

func (*ArgClause) URL 

func (p *ArgClause) URL() (target **url.URL)

URL provides a valid, parsed url.URL.

func (*ArgClause) URLList 

func (p *ArgClause) URLList() (target *[]*url.URL)

URLList provides a parsed list of url.URL values.

func (*ArgClause) URLListVar 

func (p *ArgClause) URLListVar(target *[]*url.URL)

URLListVar provides a parsed list of url.URL values.

func (*ArgClause) URLVar 

func (p *ArgClause) URLVar(target **url.URL)

URL provides a valid, parsed url.URL.

func (*ArgClause) Uint64 

func (p *ArgClause) Uint64() (target *uint64)

Uint64 parses a uint64

func (*ArgClause) Uint64List 

func (p *ArgClause) Uint64List() (target *[]uint64)

Uint64List accumulates uint64 values into a slice.

func (*ArgClause) Uint64ListVar 

func (p *ArgClause) Uint64ListVar(target *[]uint64)

func (*ArgClause) Uint64Var 

func (p *ArgClause) Uint64Var(target *uint64)

Uint64 parses a uint64

type ArgGroupModel 

type ArgGroupModel struct {
	Args []*ArgModel
}

func (*ArgGroupModel) ArgSummary 

func (a *ArgGroupModel) ArgSummary() string

type ArgModel 

type ArgModel struct {
	Name     string
	Help     string
	Default  string
	Required bool
	Value    Value
}

func (*ArgModel) String 

func (a *ArgModel) String() string

type CmdClause 

type CmdClause struct {
	// contains filtered or unexported fields
}

A CmdClause is a single top-level command. It encapsulates a set of flags and either subcommands or positional arguments.

func Command 

func Command(name, help string) *CmdClause

Command adds a new command to the default parser.

func (*CmdClause) Action 

func (c *CmdClause) Action(dispatch Action) *CmdClause

func (CmdClause) Arg 

func (a CmdClause) Arg(name, help string) *ArgClause

func (*CmdClause) Command added in v1.2.6 

func (c *CmdClause) Command(name, help string) *CmdClause

Command adds a new sub-command.

func (CmdClause) Flag 

func (f CmdClause) Flag(name, help string) *FlagClause

Flag defines a new flag with the given long name and help.

func (*CmdClause) FullCommand added in v1.3.1 

func (c *CmdClause) FullCommand() string

func (*CmdClause) Model 

func (c *CmdClause) Model() *CmdModel

func (*CmdClause) Validate added in v1.3.3 

func (c *CmdClause) Validate(validator CmdClauseValidator) *CmdClause

Validate sets a validation function to run when parsing.

type CmdClauseValidator added in v1.3.3 

type CmdClauseValidator func(*CmdClause) error

type CmdGroupModel 

type CmdGroupModel struct {
	Commands []*CmdModel
}

func (*CmdGroupModel) FlattenedCommands 

func (c *CmdGroupModel) FlattenedCommands() (out []*CmdModel)

type CmdModel 

type CmdModel struct {
	Name        string
	Help        string
	FullCommand string
	Depth       int
	*FlagGroupModel
	*ArgGroupModel
	*CmdGroupModel
}

func (*CmdModel) String 

func (c *CmdModel) String() string

type FlagClause 

type FlagClause struct {
	// contains filtered or unexported fields
}

FlagClause is a fluid interface used to build flags.

func Flag 

func Flag(name, help string) *FlagClause

Flag adds a new flag to the default parser.

func (*FlagClause) Action 

func (f *FlagClause) Action(dispatch Action) *FlagClause

Dispatch to the given function when the flag is parsed.

func (*FlagClause) Bool 

func (f *FlagClause) Bool() (target *bool)

Bool makes this flag a boolean flag.

func (*FlagClause) BoolVar 

func (p *FlagClause) BoolVar(target *bool)

Bool sets the parser to a boolean parser. Supports --no-<X> to disable the flag.

func (*FlagClause) Bytes added in v1.2.0 

func (p *FlagClause) Bytes() (target *units.Base2Bytes)

Bytes parses numeric byte units. eg. 1.5KB

func (*FlagClause) BytesVar added in v1.2.0 

func (p *FlagClause) BytesVar(target *units.Base2Bytes)

BytesVar parses numeric byte units. eg. 1.5KB

func (*FlagClause) Default 

func (f *FlagClause) Default(value string) *FlagClause

Default value for this flag. It *must* be parseable by the value of the flag.

func (*FlagClause) Duration 

func (p *FlagClause) Duration() (target *time.Duration)

Duration sets the parser to a time.Duration parser.

func (*FlagClause) DurationList 

func (p *FlagClause) DurationList() (target *[]time.Duration)

DurationList accumulates time.Duration values into a slice.

func (*FlagClause) DurationListVar 

func (p *FlagClause) DurationListVar(target *[]time.Duration)

func (*FlagClause) DurationVar 

func (p *FlagClause) DurationVar(target *time.Duration)

Duration sets the parser to a time.Duration parser.

func (*FlagClause) Enum added in v1.2.0 

func (p *FlagClause) Enum(options ...string) (target *string)

Enum allows a value from a set of options.

func (*FlagClause) EnumVar added in v1.2.0 

func (p *FlagClause) EnumVar(target **string, options ...string)

EnumVar allows a value from a set of options.

func (*FlagClause) Enums added in v1.3.6 

func (p *FlagClause) Enums(options ...string) (target *[]string)

Enums allows a set of values from a set of options.

func (*FlagClause) EnumsVar added in v1.3.6 

func (p *FlagClause) EnumsVar(target *[]string, options ...string)

EnumVar allows a value from a set of options.

func (*FlagClause) ExistingDir 

func (p *FlagClause) ExistingDir() (target *string)

ExistingDir sets the parser to one that requires and returns an existing directory.

func (*FlagClause) ExistingDirVar 

func (p *FlagClause) ExistingDirVar(target *string)

ExistingDir sets the parser to one that requires and returns an existing directory.

func (*FlagClause) ExistingFile 

func (p *FlagClause) ExistingFile() (target *string)

ExistingFile sets the parser to one that requires and returns an existing file.

func (*FlagClause) ExistingFileVar 

func (p *FlagClause) ExistingFileVar(target *string)

ExistingFile sets the parser to one that requires and returns an existing file.

func (*FlagClause) File 

func (p *FlagClause) File() (target **os.File)

File returns an os.File against an existing file.

func (*FlagClause) FileVar 

func (p *FlagClause) FileVar(target **os.File)

FileVar opens an existing file.

func (*FlagClause) Float 

func (p *FlagClause) Float() (target *float64)

Float sets the parser to a float64 parser.

func (*FlagClause) FloatVar 

func (p *FlagClause) FloatVar(target *float64)

Float sets the parser to a float64 parser.

func (*FlagClause) Hidden added in v1.2.0 

func (f *FlagClause) Hidden() *FlagClause

Hidden hides a flag from usage but still allows it to be used.

func (*FlagClause) IP 

func (p *FlagClause) IP() (target *net.IP)

IP sets the parser to a net.IP parser.

func (*FlagClause) IPList 

func (p *FlagClause) IPList() (target *[]net.IP)

IPList accumulates net.IP values into a slice.

func (*FlagClause) IPListVar 

func (p *FlagClause) IPListVar(target *[]net.IP)

func (*FlagClause) IPVar 

func (p *FlagClause) IPVar(target *net.IP)

IP sets the parser to a net.IP parser.

func (*FlagClause) Int 

func (p *FlagClause) Int() (target *int)

Int sets the parser to an int parser.

func (*FlagClause) Int64 

func (p *FlagClause) Int64() (target *int64)

Int64 parses an int64

func (*FlagClause) Int64List 

func (p *FlagClause) Int64List() (target *[]int64)

Int64List accumulates int64 values into a slice.

func (*FlagClause) Int64ListVar 

func (p *FlagClause) Int64ListVar(target *[]int64)

func (*FlagClause) Int64Var 

func (p *FlagClause) Int64Var(target *int64)

Int64 parses an int64

func (*FlagClause) IntVar 

func (p *FlagClause) IntVar(target *int)

Int sets the parser to an int parser.

func (*FlagClause) Model 

func (f *FlagClause) Model() *FlagModel

func (*FlagClause) OpenFile added in v1.1.0 

func (p *FlagClause) OpenFile(flag int, perm os.FileMode) (target **os.File)

File attempts to open a File with os.OpenFile(flag, perm).

func (*FlagClause) OpenFileVar added in v1.1.0 

func (p *FlagClause) OpenFileVar(target **os.File, flag int, perm os.FileMode)

OpenFileVar calls os.OpenFile(flag, perm)

func (*FlagClause) OverrideDefaultFromEnvar added in v0.3.0 

func (f *FlagClause) OverrideDefaultFromEnvar(envar string) *FlagClause

OverrideDefaultFromEnvar overrides the default value for a flag from an environment variable, if available.

func (*FlagClause) PlaceHolder added in v0.2.0 

func (f *FlagClause) PlaceHolder(placeholder string) *FlagClause

PlaceHolder sets the place-holder string used for flag values in the help. The default behaviour is to use the value provided by Default() if provided, then fall back on the capitalized flag name.

func (*FlagClause) Required 

func (f *FlagClause) Required() *FlagClause

Required makes the flag required. You can not provide a Default() value to a Required() flag.

func (*FlagClause) SetValue 

func (p *FlagClause) SetValue(value Value)

func (*FlagClause) Short 

func (f *FlagClause) Short(name byte) *FlagClause

Short sets the short flag name.

func (*FlagClause) String 

func (p *FlagClause) String() (target *string)

String sets the parser to a string parser.

func (*FlagClause) StringMap 

func (p *FlagClause) StringMap() (target *map[string]string)

StringMap provides key=value parsing into a map.

func (*FlagClause) StringMapVar 

func (p *FlagClause) StringMapVar(target *map[string]string)

StringMap provides key=value parsing into a map.

func (*FlagClause) StringVar 

func (p *FlagClause) StringVar(target *string)

String sets the parser to a string parser.

func (*FlagClause) Strings 

func (p *FlagClause) Strings() (target *[]string)

Strings accumulates string values into a slice.

func (*FlagClause) StringsVar 

func (p *FlagClause) StringsVar(target *[]string)

func (*FlagClause) TCP 

func (p *FlagClause) TCP() (target **net.TCPAddr)

TCP (host:port) address.

func (*FlagClause) TCPList 

func (p *FlagClause) TCPList() (target *[]*net.TCPAddr)

TCPList accumulates *net.TCPAddr values into a slice.

func (*FlagClause) TCPListVar 

func (p *FlagClause) TCPListVar(target *[]*net.TCPAddr)

func (*FlagClause) TCPVar 

func (p *FlagClause) TCPVar(target **net.TCPAddr)

TCPVar (host:port) address.

func (*FlagClause) URL 

func (p *FlagClause) URL() (target **url.URL)

URL provides a valid, parsed url.URL.

func (*FlagClause) URLList 

func (p *FlagClause) URLList() (target *[]*url.URL)

URLList provides a parsed list of url.URL values.

func (*FlagClause) URLListVar 

func (p *FlagClause) URLListVar(target *[]*url.URL)

URLListVar provides a parsed list of url.URL values.

func (*FlagClause) URLVar 

func (p *FlagClause) URLVar(target **url.URL)

URL provides a valid, parsed url.URL.

func (*FlagClause) Uint64 

func (p *FlagClause) Uint64() (target *uint64)

Uint64 parses a uint64

func (*FlagClause) Uint64List 

func (p *FlagClause) Uint64List() (target *[]uint64)

Uint64List accumulates uint64 values into a slice.

func (*FlagClause) Uint64ListVar 

func (p *FlagClause) Uint64ListVar(target *[]uint64)

func (*FlagClause) Uint64Var 

func (p *FlagClause) Uint64Var(target *uint64)

Uint64 parses a uint64

type FlagGroupModel 

type FlagGroupModel struct {
	Flags []*FlagModel
}

func (*FlagGroupModel) FlagSummary 

func (f *FlagGroupModel) FlagSummary() string

type FlagModel 

type FlagModel struct {
	Name        string
	Help        string
	Short       byte
	Default     string
	Envar       string
	PlaceHolder string
	Required    bool
	Hidden      bool
	Value       Value
}

func (*FlagModel) FormatPlaceHolder 

func (f *FlagModel) FormatPlaceHolder() string

func (*FlagModel) IsBoolFlag 

func (f *FlagModel) IsBoolFlag() bool

func (*FlagModel) String 

func (f *FlagModel) String() string

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 ParseContext added in v1.3.0 

type ParseContext struct {
	SelectedCommand *CmdClause

	// Flags, arguments and commands encountered and collected during parse.
	Elements []*ParseElement
	// contains filtered or unexported fields
}

ParseContext holds the current context of the parser. When passed to Action() callbacks Elements will be fully populated with *FlagClause, *ArgClause and *CmdClause values and their corresponding arguments (if any).

func (*ParseContext) EOL 

func (p *ParseContext) EOL() bool

func (*ParseContext) HasTrailingArgs 

func (p *ParseContext) HasTrailingArgs() bool

HasTrailingArgs returns true if there are unparsed command-line arguments. This can occur if the parser can not match remaining arguments.

func (*ParseContext) Next added in v1.3.0 

func (p *ParseContext) Next() *Token

Next token in the parse context.

func (*ParseContext) Peek added in v1.3.0 

func (p *ParseContext) Peek() *Token

func (*ParseContext) String added in v1.3.2 

func (p *ParseContext) String() string

type ParseElement 

type ParseElement struct {
	// Clause is either *CmdClause, *ArgClause or *FlagClause.
	Clause interface{}
	// Value is corresponding value for an ArgClause or FlagClause (if any).
	Value *string
}

A union of possible elements in a parse stack.

type Settings 

type Settings interface {
	SetValue(value Value)
}

type Token added in v1.3.0 

type Token struct {
	Index int
	Type  TokenType
	Value string
}

func (*Token) Equal 

func (t *Token) Equal(o *Token) bool

func (*Token) IsEOF added in v1.3.0 

func (t *Token) IsEOF() bool

func (*Token) IsFlag added in v1.3.0 

func (t *Token) IsFlag() bool

func (*Token) String added in v1.3.0 

func (t *Token) String() string

type TokenType added in v1.3.0 

type TokenType int
const (
	TokenShort TokenType = iota
	TokenLong
	TokenArg
	TokenError
	TokenEOL
)

Token types.

func (TokenType) String 

func (t TokenType) 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, and adds a --no-name counterpart for negating the flag.

Example

This example ilustrates how to define custom parsers. HTTPHeader cumulatively parses each encountered --header flag into a http.Header struct. 

package main

import (
	"fmt"
	"net/http"
	"strings"
)

type HTTPHeaderValue http.Header

func (h *HTTPHeaderValue) Set(value string) error {
	parts := strings.SplitN(value, ":", 2)
	if len(parts) != 2 {
		return fmt.Errorf("expected HEADER:VALUE got '%s'", value)
	}
	(*http.Header)(h).Add(parts[0], parts[1])
	return nil
}

func (h *HTTPHeaderValue) String() string {
	return ""
}

func HTTPHeader(s Settings) (target *http.Header) {
	target = new(http.Header)
	s.SetValue((*HTTPHeaderValue)(target))
	return
}

// This example ilustrates how to define custom parsers. HTTPHeader
// cumulatively parses each encountered --header flag into a http.Header struct.
func main() {
	var (
		curl    = New("curl", "transfer a URL")
		headers = HTTPHeader(curl.Flag("headers", "Add HTTP headers to the request.").Short('H').PlaceHolder("HEADER:VALUE"))
	)

	curl.Parse([]string{"-H Content-Type:application/octet-stream"})
	for key, value := range *headers {
		fmt.Printf("%s = %s\n", key, value)
	}
}

Output:

Source Files

View all Source files

Directories

Path Synopsis
examples
chat1
chat2
curl
A curl-like HTTP command-line client.
 A curl-like HTTP command-line client.
modular
ping

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