# $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>