All non-flag options in Clon
are said to be valued. All valued
options, including those you define yourself (see New Option Types),
share a set of additional properties. Here is a list of them.
:argument-name
¶The name of the option’s argument, as it appears in the help string. It
defaults to "ARG"
, so that for instance, a ‘name’ option
would appear like this: ‘--name=ARG’.
:argument-type
¶The status of the argument. Possible values are :required
(the
default) and :mandatory
which are synonyms, or :optional
.
:fallback-value
¶:default-value
¶The option’s fallback and default values. Remember that a fallback value only makes sense when the argument is optional. Besides, also when the argument is optional, you need to provide at least a fallback or a default value (or both of course; see Value Sources in The Clon End-User Manual).