module Opt:sig
..end
This module contains the basic functions and types for defining new option types and accessing the values of options.
exception No_value
No_value
gets raised by OptParse.Opt.get
when an option
value is not available.
exception Option_error of string * string
This exception signals that an option value is invalid. The first string contains the option string ('-x' or '--long-name') and the second string contains an error message.
This exception is only used when implementing custom option types
and can never "escape" the scope of a OptParse.OptParser.parse
.
The user should therefore not attempt to catch it.
exception Option_help
When an option wants to display a usage message, this exception
may be raised. It can never "escape" the scope of a
OptParse.OptParser.parse
call and the user should therefore not
attempt to catch it.
type 'a
t = {
|
option_set : |
|
option_set_value : |
|
option_get : |
|
option_metavars : |
|
option_defhelp : |
}
Option type.
option_set
is a closure which converts and records the value of
an option so that it can be retrieved with a later call to the
option_get
closure. It is called with the option name which was
given on the command line and a list of strings, each representing
one of the argument values given on the command line. It may raise
Option_error
if the value is invalid (for whatever reason).
option_set_value
is a closure which sets the value of an option
to a particular value.
option_get
is a closure which retrieves the recorded value
of the option. If the option value has not been set from the
command line, the default value is used. If there is no default
value, then None
should be returned.
option_metavars
is a list of "meta-variables" (arguments)
which this option accepts. This is mainly for display purposes,
but the length of this list determines how many arguments the
option parser accepts for this option (currently only lists of
length 0 or 1 are supported).
option_defhelp
is the default help string (if any). It is
used for displaying help messages whenever the user does not specify a help string manually when adding this
option. Using a non-None value here only makes sense for
completely generic options like OptParse.StdOpt.help_option
.
val get : 'a t -> 'a
Get the value of an option.
No_value
if no default values has been given
and the option value has not been set from the command line.val set : 'a t -> 'a -> unit
Set the value of an option.
val opt : 'a t -> 'a option
Get the value of an option as an optional value.
Some x
if the option has value x
(either by default or
from the command line). If the option doesn't have a value None
is returned.val is_set : 'a t -> bool
Find out if the option has a value (either by default or from the command line).
True
iff the option has a value.val value_option : string ->
'a option ->
(string -> 'a) -> (exn -> string -> string) -> 'a t
Make an option which takes a single argument.
value_option metavar default coerce errfmt
returns an option
which takes a single argument from the command line and calls
coerce
to coerce it to the proper type. If coerce
raises an
exception, exn
, then errfmt exn argval
is called to generate
an error message for display. metavar
is the name of the
metavariable of the option.
default
is the default value of the option. If None
, the
option has no default value.
val callback_option : string ->
(string -> 'a) ->
(exn -> string -> string) -> ('a -> unit) -> unit t
Make a callback option which takes a single argument.
callback_option metavar coerce errfmt f
returns an option which
takes a single argument from the command line and calls coerce
to coerce it to the proper type. If coerce
raises an exception
errfmt exn argval
is called to format an error message for
display. If coerce
succeeds, the callback function f
is called
with the coerced value. Finally, metavar
is the name of the
metavariable of the option.