Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.2 9/18/84; site brl-tgr.ARPA
Path: utzoo!watmath!clyde!burl!ulysses!allegra!mit-eddie!think!harvard!seismo!brl-tgr!tgr!cottrell@nbs-vms.ARPA
From: cottrell@nbs-vms.ARPA (COTTRELL, JAMES)
Newsgroups: net.lang.c
Subject: I Do Declare!
Message-ID: <1113@brl-tgr.ARPA>
Date: Thu, 29-Aug-85 17:09:59 EDT
Article-I.D.: brl-tgr.1113
Posted: Thu Aug 29 17:09:59 1985
Date-Received: Sat, 31-Aug-85 08:19:16 EDT
Sender: news@brl-tgr.ARPA
Lines: 41

/*
In article <368@persci.UUCP> roman@persci.UUCP writes:
> Either I'm missing the perfectly obvious or I've found something
> that's impossible to declare in C, even though it makes sense.  I'm
> trying to implement a simple finite state machine with states
> represented by C functions.  Each state function would accept some
> input value as an argument and return a pointer to the function
> implementing the next state...

Cheat! Declare your variable as a pointer to funxion returning int
(or char (or void) pointer for sticklers) and then use casts.
Saves a lot of headaches trying to figure out all those types.
With char or void pointers, there ought to be a portable way.

typedef	int	 (*PFI)();
typedef char	*(*PFCP)();	/* for portability sticklers */
typedef void	*(*PFVP)();	/* if available */

int	other();
int	init();			/* initial func */
PFI	state = init;		/* state var */

init(arg)
{
	state = other;		/* no problem to set directly */
	...
	return((int)state);	/* to return we must cast */
	...
	state = (PFI)other(arg);/* must cast to assign */
	...
	(*state)(arg);		/* can be called directly */
	...
	while (state = (PFI)(*state)(arg));	/* until no more funx */
}

Once in a while you get shown the light
In the strangest of places if you look at it right.

	jim		cottrell@nbs
*/
------