The g-option-arg enumeration determines which type of extra argument the options expect to find. If an option expects an extra argument, it can be specified in several ways, with a short option: -x arg, with a long option: --name arg or combined in a single argument: --name=arg.

(defcenum g-option-arg
  :none
  :string
  :int
  :callback
  :filename
  :string-array
  :filename-array
  :double
  :int64)  

:none

No extra argument. This is useful for simple flags.

:string

The option takes a string argument.

:int

The option takes an integer argument.

:callback

The option provides a callback function to parse the extra argument.

:filename

The option takes a filename as argument.

:string-array

The option takes a string argument, multiple uses of the option are collected into a list of strings.

:filename-array

The option takes a filename as argument, multiple uses of the option are collected into a list of strings.

:double

The option takes a double float argument. The argument can be formatted either for the locale of the user or for the "C" locale.

:int64

The option takes a 64-bit integer. Like :int but for larger numbers. The number can be in decimal base, or in hexadecimal, when prefixed with 0x, for example, 0xffffffff.