blob: 7617efe3511fc87ab364d0940e3dfcfb54bdfd13 [file] [log] [blame]
package flags
import (
// Option flag information. Contains a description of the option, short and
// long name as well as a default value and whether an argument for this
// flag is optional.
type Option struct {
// The short name of the option (a single character). If not 0, the
// option flag can be 'activated' using -<ShortName>. Either ShortName
// or LongName needs to be non-empty.
ShortName rune
// The long name of the option. If not "", the option flag can be
// activated using --<LongName>. Either ShortName or LongName needs
// to be non-empty.
LongName string
// The description of the option flag. This description is shown
// automatically in the builtin help.
Description string
// The default value of the option.
Default []string
// If true, specifies that the argument to an option flag is optional.
// When no argument to the flag is specified on the command line, the
// value of Default will be set in the field this option represents.
// This is only valid for non-boolean options.
OptionalArgument bool
// The optional value of the option. The optional value is used when
// the option flag is marked as having an OptionalArgument. This means
// that when the flag is specified, but no option argument is given,
// the value of the field this option represents will be set to
// OptionalValue. This is only valid for non-boolean options.
OptionalValue []string
// If true, the option _must_ be specified on the command line. If the
// option is not specified, the parser will generate an ErrRequired type
// error.
Required bool
// A name for the value of an option shown in the Help as --flag [ValueName]
ValueName string
// The struct field which the option represents.
Field reflect.StructField
// The struct field value which the option represents.
Value reflect.Value
defaultValue reflect.Value
iniUsedName string
tag multiTag
// Set the value of an option to the specified value. An error will be returned
// if the specified value could not be converted to the corresponding option
// value type.
func (option *Option) Set(value *string) error {
if option.isFunc() {
} else if value != nil {
return convert(*value, option.Value, option.tag)
} else {
return convert("", option.Value, option.tag)
return nil
// Convert an option to a human friendly readable string describing the option.
func (option *Option) String() string {
var s string
var short string
if option.ShortName != 0 {
data := make([]byte, utf8.RuneLen(option.ShortName))
utf8.EncodeRune(data, option.ShortName)
short = string(data)
if len(option.LongName) != 0 {
s = fmt.Sprintf("-%s, --%s", short, option.LongName)
} else {
s = fmt.Sprintf("-%s", short)
} else if len(option.LongName) != 0 {
s = fmt.Sprintf("--%s", option.LongName)
return s