Command-line argument parsing: Difference between revisions

Revision as of 17:03, 10 February 2011

Revision as of 11:37, 17 August 2011

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print arg

</source>

===Racket===

[[Racket (programming language)|Racket]] uses a <code>current-command-line-arguments</code> parameter, and provides a <code>racket/cmdline</code><ref>[http://docs.racket-lang.org/reference/Command-Line_Parsing.html The Racket reference manual, Command-Line Parsing]</ref> library for parsing these arguments. Example:

<source lang="scheme">

#lang racket

(require racket/cmdline)

(define smile? #true)

(define nose? #false)

(define eyes ":")

(command-line

#:program "emoticon"

#:once-any ; the following two are mutually exclusive

[("-s" "--smile") "smile mode" (set! smile? #true)]

[("-f" "--frown") "frown mode" (set! smile? #false)]

#:once-each

[("-n" "--nose") "add a nose" (set! nose? #true)]

[("-e" "--eyes") char "use <char> for the eyes" (set! eyes char)])

(printf "~a~a~a\n" eyes (if nose? "-" "") (if smile? ")" "("))

</source>

The library parses long and short flags, handles arguments, allows combining short flags, and handles <code>-h</code> and <code>--help</code> automatically:

<pre>

$ racket /tmp/c -nfe 8

8-(

</pre>

==References==