Outdated egg! (historical revision 39572)

You are looking at historical revision 39572 of this page. It may differ significantly from its current revision.

Outdated egg!

This is an egg for CHICKEN 4, the unsupported old release. You're almost certainly looking for the CHICKEN 5 version of this egg, if it exists.

If it does not exist, there may be equivalent functionality provided by another egg; have a look at the egg index. Otherwise, please consider porting this egg to the current version of CHICKEN.

easy-args

Outdated egg!
easy-args
Description
Requirements
API
Examples
History
Author
License

Description

Handle command-line arguments as parameter objects.

This egg is no longer maintained. Please refer to srfi-37, args or getopt-long for other command-line argument handling libraries for CHICKEN 4.

API

define-arguments

[syntax] (define-arguments (name [value [guard]]) ...)

define-arguments defines parameter objects for the given command line option names and sets them according to the program's command-line-arguments parameter.

For each specified argument, name should be an identifier or list of identifiers. The first of these will be bound to the newly-created parameter object. value, if given, must be a boolean, string, number or symbol, and will be the default value of the parameter object. If no value is given, #f is used. If a procedure guard is given, it is used as the parameter object's conversion procedure.

Each name, when prefixed by one dash (in the case of a single-character identifier) or two (for all others), will be used as a command-line flag to set the corresponding parameter object's value. If name contains asterisks, they are stripped from the flag.

define-arguments reads and modifies Chicken's command-line-arguments parameter, setting matched parameter objects to the specified values and removing their options from the list. Unmatched arguments are accumulated into an alist accessible by the unmatched-arguments procedure. Upon completion, command-line-arguments will contain any non-option arguments to the program. The return value is unspecified.

invalid-argument-handler

[parameter] invalid-argument-handler

invalid-argument-handler is called when define-arguments encounters an invalid command-line value. It is a procedure of three arguments: an error message (string), option name (string or character) and value (a string or #t). By default, this procedure simply prints an error message and exits the program.

unmatched-arguments

[procedure] (unmatched-arguments)

Returns an alist of the command-line arguments unmatched by define-arguments. If called before define-arguments, it will return an empty list.

Examples

(use easy-args extras)

(define-arguments
  (all-caps)
  (prompt "Your name? ")
  ((exclamations e) 1))

(display (prompt))

(let ((message (string-join `("Hello," ,(read-line)))))
  (if (all-caps)
    (display (string-upcase message))
    (display message)))

(print (make-string (exclamations) #\!))

(if (not (null? (unmatched-arguments)))
  (print (unmatched-arguments)))

With the file above as greeter.scm:

 $ csc greeter.scm
 
 $ ./greeter
 Your name? [Henrietta]
 Hello, Henrietta!
 
 $ ./greeter --all-caps
 Your name? [Henrietta]
 HELLO, HENRIETTA!
 
 $ ./greeter --prompt 'Name: ' -e3
 Name: [Henrietta]
 Hello, Henrietta!!!
 
 $ ./greeter -w --unmatched=args
 Your name? Henrietta
 Hello, Henrietta!
 ((w . #t) (unmatched . args))