SYNOPSIS
	void notify_fail(string str, int priority)
	void notify_fail(closure cl, int priority)

DESCRIPTION
	Store str as the error message given instead of the default
	message ``What ?''.
	
	If a closure is given, it is executed to return the error
	message string, but not before all attempts to execute the
	commandline failed (read: not at the time of the call to
	notify_fail()).

	However the message string is generated, it is word-wrapped to
	78 characters per line before printing.
	
	If notify_fail() is called more than once, only the last call
	will be used.
	
	The idea of this function is to give better error messages
	instead of simply 'What ?'.
	
	It is also better to use
		notify_fail(message); return 0;
	instead of
		write(message); return 1;
	
	Other objects will get the chance to evaluate the verb.

	The 'priority' is an OSB-specific invention, it allows
	you to define how badly the command failed. Recognized are are
	the priorities defined in /sys/config.h:
	  NOTIFY_NOT_CMD (-1): 
            The object does not support the command at all.
	  NOTIFY_NOT_OBJ ( 0): 
            The object supports the command in general, but is not the
            one meant in the actual command.
	  NOTIFY_ILL_ARG ( 1): 
            The object supports the command in general, but is either
            not the one meant with the actual command, or is given an
            invalid command (this is needed for commands which do not
            specifiy the object unambiguously).
	  NOTIFY_NOT_VALID ( 2):
	    The object supports the command and _is_ the one meant in
	    the actual command, but can't complete its task due to
	    some internal reason (like syntax errors in the command
	    arguments).
	  NOTIFY_DO_ALL (max int):
	    Not a real failure message, this one allows the repeated
	    execution of the same command for other objects (e.g. for
	    a 'wear all').

EXAMPLE
	To implement is a command 'foo <object> to <object>', which is
	available for wizards only, and may also be shortened to 'foo
	to <object>'.

	#define TP this_player()

	int foo(string arg) {
	  string str1, str2;
	  object obj1, obj2;

	  if (IS_PLAYER(TP)) {
	    notify_fail("Nothing happens.\n", NOTIFY_NOT_CMD);
	    return 0;
	  }
	  // First check for the short form.
	  // Note the _ILL_ARG in case the specified object is not found.
	  if (1 == sscanf(arg, "to %s", str2)) { // Handle short form
	    if (!(obj2 = TP->Search(str2, SEARCH_ENV, SEARCH_OBJECT))) {
	      notify_fail("Foo to what?\n", NOTIFY_ILL_ARG);
	      return 0;
	    }
	    obj1 = this_object();
	  }
	  else { 
	    // Check the long form.
	    if (   2 != sscanf(arg, "%s to %s", str1, str2)
	        || !(obj1 = TP->Search(str1, SEARCH_ENV, SEARCH_OBJECT))
	        || obj1 != this_object()
               ) {
	      notify_fail("Foo what?\n", NOTIFY_NOT_OBJ);
	      return 0;
	    }
	    if (!(obj2 = TP->Search(str2, SEARCH_ENV, SEARCH_OBJECT))) {
	      notify_fail("Foo to what?\n", NOTIFY_NOT_VALID);
	      return 0;
	    }
	  }
	  if (obj2->QueryWeight() > 3000) {
	    notify_fail( "You need a lighter object to foo to.\n"
	               , NOTIFY_NOT_VALID);
	    return 0;
	  }
	  obj2->SetProp("FooedBy", this_object());
	  write("Well, you asked for it, you got it.\n");
	  return 1;
	}

SEE ALSO
	add_action(E), query_verb(E)