Xref: utzoo comp.lang.c:9814 comp.software-eng:504
Path: utzoo!mnetor!uunet!husc6!cca!g-rh
From: g-rh@cca.CCA.COM (Richard Harter)
Newsgroups: comp.lang.c,comp.software-eng
Subject: State Machines, The Ultimate Goto
Message-ID: <27568@cca.CCA.COM>
Date: 1 May 88 00:15:05 GMT
References: <1988Apr8.183815.3187@utzoo.uucp> <449@goofy.megatest.UUCP> <2200@louie.udel.EDU> <587@vsi.UUCP> <27310@cca.CCA.COM> <760@dlhpedg.co.uk>
Reply-To: g-rh@CCA.CCA.COM.UUCP (Richard Harter)
Organization: Computer Corp. of America, Cambridge, MA
Lines: 36

In article <760@dlhpedg.co.uk> cl@datlog.co.uk (Charles Lambert) writes:
>In article <27310@cca.CCA.COM> g-rh@CCA.CCA.COM.UUCP (Richard Harter) writes:

>>f)	Put the test condition in a while statement and step through the
>>	actions [somehow].  Unfortunately, I don't see a nice way to do
>>	this in C.  The thought that first occurs to one is something like

	... sample code deleted

>This is almost a finite-state machine, and state machine programming is an
>accepted idiom. Generalise it as follows:

	... sample code deleted

Strange throat noises resembling the mating call of a frog.  [That there
is a comment.]

State machines are all very well in their way -- I use them myself --
but state machine logic is quintessential goto logic.  The essence of
state machine logic is that it doesn't matter where you came from;  all
that matters are the appropriate actions for this state and the appropriate
state to transfer to next.

From a flow control viewpoint, entering a state machine is like falling into
a pin ball machine.  You bang around here and there and (if there is a 
guaranteed halting condition) you eventually get out.

Goto logic says leave and don't come back.  Heirarchical logic says leave
and come back.  The prescription against goto's really means -- don't mix
the two types of structure.

-- 

In the fields of Hell where the grass grows high
Are the graves of dreams allowed to die.
	Richard Harter, SMDS  Inc.