QCaml/common/command_line.org

• Command line
  • Type
  • Mutable attributes
  • Query functions
  • Specification

Command line

This module is a wrapper around the Getopt library and helps to define command-line arguments.

Here is an example of how to use this module. First, define the specification:

let open Command_line in
begin
set_header_doc (Sys.argv.(0) ^ " - One-line description");
set_description_doc "Long description of the command.";
set_specs
  [ { short='c'; long="check"; opt=Optional;
      doc="Checks the input data";
      arg=Without_arg; };

    { short='b' ; long="basis" ; opt=Mandatory;
      arg=With_arg "<string>";
      doc="Name of the file containing the basis set"; } ;

    { short='m' ; long="multiplicity" ; opt=Optional;
      arg=With_arg "<int>";
      doc="Spin multiplicity (2S+1). Default is singlet"; } ;
  ]
end;

Then, define what to do with the arguments:

let c =
Command_line.get_bool "check"
in

let basis =
match Command_line.get "basis" with
| Some x -> x
| None -> assert false
in

let multiplicity =
match Command_line.get "multiplicity" with
| None -> 1
| Some n -> int_of_string n
in

Type

#+NAME:type

type short_opt     = char
type long_opt      = string
type optional      = Mandatory | Optional
type documentation = string
type argument      = With_arg of string | Without_arg | With_opt_arg of string

type description = {
short: short_opt ;
long : long_opt  ;
opt  : optional  ;
doc  : documentation ;
arg  : argument ;
}

• Short option: in the command line, a dash with a single character (ex: ls -l)
• Long option: in the command line, two dashes with a word (ex: ls --directory)
• Command-line options can be Mandatory or Optional
• Documentation of the option is used in the help function
• Some options require an argument (ls --ignore="*.ml" ), some don't (ls -l) and for some arguments the argument is optional (git --log[=<n>])

Mutable attributes

All the options are stored in the hash table dict where the key is the long option and the value is a value of type description.

val set_header_doc : string -> unit
val set_description_doc : string -> unit
val set_footer_doc : string -> unit

Functions to set the header, footer and main description of the documentation provided by the help function:

val anonymous : long_opt -> optional -> documentation -> description

Function to create an anonymous argument.

Query functions

val get       : long_opt -> string option
val get_bool  : long_opt -> bool
val anon_args : unit -> string list

get	Returns the argument associated with a long option
get_bool	True if the Optional argument is present in the command-line
anon_args	Returns the list of anonymous arguments

Specification

val set_specs : description list -> unit

Sets the specifications of the current program from a list of descrption variables.