[Click] compound element keyword arguments

[Eddie Kohler]

Hi all,

Click compound elements now support keyword arguments and "rest" arguments.

Examples:

   elementclass Foo {
     input -> Print -> output     /* no arguments */
   ||
     $a | input -> Print($a) -> output   /* one positional argument */
   ||
     COLOR $t | input ->  Print($t) -> output  /* a keyword argument */
   ||
     $a, TS $c, __REST__ $rest |    /* 1 positional, 1 keyword, 1 rest */
        input -> Print($a, TIMESTAMP $c, $rest) -> output
   }

   Foo();   /* uses definition 1 */
   Foo(what);   /* uses 2 with $a == 'what' */
   Foo(COLOR red);  /* uses 3 with $t == 'red' */
   Foo(money, whatever, TS true, OTHER foo)
	      /* uses 4 with $a == 'money', $c == 'true', and
		 $rest == 'whatever, OTHER foo' */

Compound elemnet keyword arguments are mandatory.  So the following is an
error, because the MANDATORY keyword is missing:

   { MANDATORY $whatever | ... } ();

It turns out that __REST__ arguments work better if empty arguments are
ignored (I mentioned this in a previous email).  So for now empty arguments
are ignored.  Doug, how about 'perl -w' for the uninitialized-variable case
you were mentioning?

Eddie