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getopt [2007/03/02 02:32] (current)
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 +# $EPIC: getopt.txt,​v 1.4 2007/03/02 02:32:04 jnelson Exp $
 +======Synopsis:​======
 +$__getopt__(<​optopt-var>​ <​optarg-var>​ <​option-list>​ <​argument-list>​)
 +
 +======Technical:​======
 +   * The <​option-list>​ argument is a [[what is a word|dword]] which is different from most function arguments.
 +   * This function should be called as the expression of a [[WHILE]] command.
 +   * If the <​optopt-var>​ argument is omitted the empty string is returned.
 +   * If the <​optarg-var>​ argument is omitted the empty string is returned.
 +   * If the <​option-list>​ argument is omitted the empty string is returned.
 +   * The <​optopt-var>​ argument is taken as the name of a variable in which to put the current option being parsed.
 +   * The <​optarg-var>​ argument is taken as the name of a variable in which to put the current argument being parsed.
 +   * The <​option-list>​ argument is taken as a list of arguments that are to be parsed from <​argument-list>​. ​ \\ Each character in <​option-list>​ permits an option by that character to be parsed. ​ \\ Each character may be followed by either a single colon which specifies that the option must always be followed by an argument, or a double colon, which specifies that the option may or may not be followed by an argument.
 +   * The <​argument-list>​ argument is taken to be word list of [[what is a word|dwords]],​ which means double quoted words are supported, and the double quotes are removed.
 +   * The <​argument-list>​ argument is taken as an argument list, perhaps to an alias, that are to be parsed. ​ \\ It is fully parsed the "first time" that $getopt() is called.
 +   * Each and every time any of the arguments to the getopt() function change between one call and the next, \\ it is considered the "first time" that the $getopt() function has been called.
 +   * The return value of the function shall be an indicator of the "​next"​ option found in <​argument-list>​. ​ \\ The "first time" that $getopt() is called, the first option in <​argument-list>​ is returned. ​ \\ The second time that $getopt() is called, the second option in <​argument-list>​ is returned, and so on.
 +   * Five things can be returned each call to $getopt().
 +      * The name of an option that does not take an argument: \\ $<​optopt-var>​ contains the name of the option. \\ $<​optarg-var>​ contains the empty string.
 +      * The name of an option that takes an argument: \\ $<​optopt-var>​ contains the name of the option. \\ $<​optarg-var>​ contains the argument to the option. \\ 
 +      * A hyphen ('​-'​) indicating an option that takes an argument and was not provided with one: \\ $<​optopt-var>​ contains the name of the option \\ $<​optarg-var>​ contains the empty string.
 +      * A bang ('​!'​) indicating an option that was not one of the options listed in <​option-list>:​ \\ $<​optopt-var>​ contains the name of the string \\ $<​optarg-var>​ contains the empty string.
 +      * An empty string indicates processing is complete or internal error: \\ $<​optopt-var>​ is empty. \\ $<​optarg-var>​ contains the remaining non-option args.
 +
 +======Practical:​======
 +Useful when you want an alias to accept option flags and you need a 
 +way to parse them easily. ​ See the example section for particulars.
 +
 +======Returns:​======
 +See technical specification for return values.
 +
 +======Examples:​======
 +<​file>​
 +alias myalias {
 +  while (option = getopt(optopt optarg "​ab:​c:"​ $*)) {
 +    switch ($option) {
 +      (a) {echo * option "​$optopt"​ used}
 +      (b) {echo * option "​$optopt"​ used - $optarg}
 +      (c) {echo * option "​$optopt"​ used - $optarg}
 +      (!) {echo * option "​$optopt"​ is an invalid option}
 +      (-) {echo * option "​$optopt"​ is missing an argument}
 +    }
 +  }
 +  echo * remaining args: $optarg
 +}
 +</​file>​
  
getopt.txt ยท Last modified: 2007/03/02 02:32 (external edit)