Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uunet!zephyr.ens.tek.com!tekcrl!tekgvs!toma
From: toma@tekgvs.LABS.TEK.COM (Tom Almy)
Newsgroups: comp.lang.forth
Subject: Re: ANS FORTH/PICK and ROLL
Message-ID: <6367@tekgvs.LABS.TEK.COM>
Date: 15 Nov 89 19:30:28 GMT
References: <931@mtk.UUCP>
Reply-To: toma@tekgvs.LABS.TEK.COM (Tom Almy)
Distribution: usa
Organization: Tektronix, Inc., Beaverton,  OR.
Lines: 26

In article <931@mtk.UUCP> marmar@mtk.UUCP (Mark Martino) writes:
>This article proposed that PICK and ROLL become members of the extended
>word set instead of being required words.  I agree with the article that
>they are fairly cumbersome, but I could not think of a way to get along
>without them.
>
>How WOULD you get along without them? 

Well I guess that this makes me really old, but I used Forth before there
was PICK and ROLL, and I got along just fine!

Two reasons to avoid them:

1) If you "need" them, then you are dealing with two many values at once
   on the stack, and will have an extremely difficult time debugging and
   especially maintaining that code.

2) Optimizing Forth compilers (such as my native code compilers) make use
   of machine registers to hold top of stack values. When PICK and ROLL
   have a non literal argument (i.e. X @ PICK rather than 4 PICK) then
   the compiler is forced to flush registers to the stack -- a decidedly
   non-optimal situation.

Tom Almy
toma@tekgvs.labs.tek.com
Standard Disclaimers Apply