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Article contents:[[tags: egg]] == optimism Command line option handling. [[toc:]] == Description This extension provides a way to collect command line options into an association list according to a simple S-expressive grammar. == Usage One procedure is provided, {{parse-command-line}}, which takes as arguments an options grammar and an optional list of command line option strings and returns an association list. If no list of options is given, the program's command line arguments are used. <enscript highlight=scheme> (import (optimism)) (parse-command-line '("-a" "-b" "one" "-c" "two" "three" "-d" "four" "5" "six") `((-a) (-b . foo) (-c bar baz) (-d ,string->symbol ,string->number))) ; => ((-a) ; (-b . "one") ; (-c "two" "three") ; (-d four 5) ; (-- "six")) </enscript> As a special case, an item in the grammar whose first element is a list will be split into separate entries. This allows the following shorthand syntax for aliases, where multiple options should have the same form: <enscript highlight=scheme> (parse-command-line '(((-f --foo) . bar))) ; The above is equivalent to: ; ; (parse-command-line ; '((-f . bar) ; (--foo . bar))) </enscript> Parsers for {{getopt(3)}} and {{getopt_long(3)}}-style command lines are provided by the {{getopt}} and {{getopt-long}} sublibraries, respectively. <enscript highlight=scheme> (import (optimism getopt)) (parse-command-line ; => ((-a) '("-abcone" "-d" "two") ; (-b) '((-a) ; (-c . "one") (-b) ; (-d . "two") (-c . one) ; (--)) (-d . two))) (import (optimism getopt-long)) (parse-command-line ; => ((-a . "one") '("-aone" "--foo" "--bar=two") ; (--foo) '((-a . one) ; (--bar . "two") (--foo) ; (--)) (--bar . two))) </enscript> === API <procedure>(parse-command-line grammar)</procedure> <procedure>(parse-command-line arguments grammar)</procedure> <procedure>(parse-command-line matcher arguments grammar)</procedure> {{parse-command-line}} parses a program's command line arguments into an association list according to an S-expressive options grammar. It takes one required and two optional arguments: an option matching procedure, an S-expressive options {{grammar}}, and a list of command line argument strings. If {{matcher}} is not given a basic string comparison is used, while {{arguments}} defaults to the value of {{(cdr (command-line))}}. {{grammar}} is a finite list of pairs whose {{car}}s are symbols and whose {{cdr}}s are pairs or atoms. All other {{car}}s in the grammar must be atoms; grammars may not be nested. The given {{arguments}} are matched as symbols against the {{car}}s of the options grammar. When a match is found, an association from the matched symbol to the arguments immediately following the matched item in the arguments list is added, following the form of the matched pair. <enscript=scheme> (parse-command-line ; => ((foo . "bar") '("foo" "bar") ; (--)) '((foo . bar))) (parse-command-line ; => ((foo) '("foo" "bar" "baz" "qux") ; (bar "baz" "qux") '((foo) ; (--)) (bar baz qux))) </enscript> Unmatched arguments are added to the resulting association list under the key {{--}}. Similarly, any arguments following a {{"--"}} in the arguments list are treated as unmatched. <enscript=scheme> (parse-command-line ; => ((foo . "bar") '("foo" "bar" "baz") ; (-- "baz")) '((foo . bar))) (parse-command-line ; => ((foo . "bar") '("foo" "bar" "--" "baz" "qux") ; (-- "baz" "qux")) '((foo . bar) (baz . qux))) </enscript> In a matched options form, procedures are replaced by the result of invoking that procedure on the corresponding item in the arguments list. All other objects are replaced by the corresponding argument string directly. <enscript=scheme> (parse-command-line ; => ((foo ("bar") 42 qux) '("foo" "bar" "42" "qux") ; (--)) `((foo ,list ,string->number ,string->symbol))) </enscript> == Author [[/users/evan-hanson|Evan Hanson]] == Repository [[https://git.foldling.org/optimism/|https://git.foldling.org/optimism/]] == License Public Domain Description of your changes:

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