• Setup
• Parsing Arguments
• Registering Flags and Options
• Retrieving Values
• Positional Arguments
• Commands

Setup

func NewParser() *ArgParser

Creates a new ArgParser instance.

You can specify .Helptext and .Version strings for the parser.

Specifying a helptext string activates an automatic --help flag (also a -h shortcut unless registered by another option).

Specifying a version string activates an automatic --version flag (also a -v shortcut unless registered by another option).

Parsing Arguments

func (parser *ArgParser) Parse()

Parses the application's command line arguments.

Registering Flags and Options

func (parser *ArgParser) NewFlag(name string)

Registers a new flag. The name parameter accepts an unlimited number of space-separated aliases and single-character shortcuts.

A flag is a valueless option — it's either present or absent, but takes no argument. You can check for the presence of a flag using the parser's .Found() method.

func (parser *ArgParser) NewFloatOption(name string, fallback float64)

Registers a new float-valued option. The name parameter accepts an unlimited number of space-separated aliases and single-character shortcuts. The fallback parameter specifies the option's default value.

func (parser *ArgParser) NewIntOption(name string, fallback int)

Registers a new integer-valued option. The name parameter accepts an unlimited number of space-separated aliases and single-character shortcuts. The fallback parameter specifies the option's default value.

func (parser *ArgParser) NewStringOption(name string, fallback string)

Registers a new string-valued option. The name parameter accepts an unlimited number of space-separated aliases and single-character shortcuts. The fallback parameter specifies the option's default value.

Retrieving Values

Any of an option's registered aliases or shortcuts can be used for the name parameter in the methods below.

func (parser *ArgParser) Count(name string) int

Returns the number of times the specified option was found.

func (parser *ArgParser) FloatValue(name string) float64

Returns the value of the specified float-valued option.

func (parser *ArgParser) FloatValues(name string) []float64

Returns the specified float-valued option's list of values.

func (parser *ArgParser) Found(name string) bool

Returns true if the specified flag or option was found.

func (parser *ArgParser) IntValue(name string) int

Returns the value of the specified integer-valued option.

func (parser *ArgParser) IntValues(name string) []int

Returns the specified integer-valued option's list of values.

func (parser *ArgParser) StringValue(name string) string

Returns the value of the specified string-valued option.

func (parser *ArgParser) StringValues(name string) []string

Returns the specified string-valued option's list of values.

Positional Arguments

Positional arguments (also known as 'free' arguments, i.e. arguments that are not option values) are appended to a slice of strings which can be accessed via the parser's .Args property.

The following convenience methods are also available for parsing the arguments as integers or floats.

func (parser *ArgParser) ArgsAsFloats() []float64

Attempts to parse and return the positional arguments as a slice of floats. Exits with an error message on failure.

func (parser *ArgParser) ArgsAsInts() []int

Attempts to parse and return the positional arguments as a slice of integers. Exits with an error message on failure.

Commands

func (parser *ArgParser) CommandName() string

Returns the command name, if the parser has found a command.

func (parser *ArgParser) CommandParser() *ArgParser

Returns the command's ArgParser instance, if the parser has found a command.

func (parser *ArgParser) EnableHelpCommand(enable bool)

This boolean switch toggles support for an automatic help command which prints subcommand helptext. The value defaults to false but gets toggled automatically to true whenever a command is registered. You can use this function to disable the feature if required.

func (parser *ArgParser) HasCommand() bool

Returns true if the parser has found a command.

func (parser *ArgParser) NewCommand(name string) *ArgParser

Registers a new command. The name parameter accepts an unlimited number of space-separated aliases for the command. Returns the command's ArgParser instance.