blob: 29e702c196012fe3fa7869fa87e1a3f6647c6dbc [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 description of the option flag. This description is shown
// automatically in the built-in help.
Description string
// 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 default value of the option.
Default []string
// The optional environment default value key name.
EnvDefaultKey string
// The optional delimiter string for EnvDefaultKey values.
EnvDefaultDelim 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
// A mask value to show in the help instead of the default value. This
// is useful for hiding sensitive information in the help, such as
// passwords.
DefaultMask string
// The group which the option belongs to
group *Group
// The struct field which the option represents.
field reflect.StructField
// The struct field value which the option represents.
value reflect.Value
// Determines if the option will be always quoted in the INI output
iniQuote bool
tag multiTag
isSet bool
// LongNameWithNamespace returns the option's long name with the group namespaces
// prepended by walking up the option's group tree. Namespaces and the long name
// itself are separated by the parser's namespace delimiter. If the long name is
// empty an empty string is returned.
func (option *Option) LongNameWithNamespace() string {
if len(option.LongName) == 0 {
return ""
// fetch the namespace delimiter from the parser which is always at the
// end of the group hierarchy
namespaceDelimiter := ""
g :=
for {
if p, ok := g.parent.(*Parser); ok {
namespaceDelimiter = p.NamespaceDelimiter
switch i := g.parent.(type) {
case *Command:
g = i.Group
case *Group:
g = i
// concatenate long name with namespace
longName := option.LongName
g =
for g != nil {
if g.Namespace != "" {
longName = g.Namespace + namespaceDelimiter + longName
switch i := g.parent.(type) {
case *Command:
g = i.Group
case *Group:
g = i
case *Parser:
g = nil
return longName
// String converts 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, %s%s",
string(defaultShortOptDelimiter), short,
defaultLongOptDelimiter, option.LongNameWithNamespace())
} else {
s = fmt.Sprintf("%s%s", string(defaultShortOptDelimiter), short)
} else if len(option.LongName) != 0 {
s = fmt.Sprintf("%s%s", defaultLongOptDelimiter, option.LongNameWithNamespace())
return s
// Value returns the option value as an interface{}.
func (option *Option) Value() interface{} {
return option.value.Interface()