Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!uwvax!umn-d-ub!umn-cs!thelake!steve
From: steve@thelake.UUCP (Steve Yelvington)
Newsgroups: comp.sys.atari.st
Subject: Re: Self-Modifying Code
Message-ID: <0927891128429423@thelake.UUCP>
Date: 27 Oct 89 16:28:42 GMT
References: <8910270333.AA14741@cscwam.UMD.EDU>
Reply-To: pwcs.StPaul.GOV!stag!thelake!steve
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In article <8910270333.AA14741@cscwam.UMD.EDU>,
     dmb@wam.UMD.EDU (David M. Baggett) writes ... 

>Richard Covert writes:

<bunch of stuff about configuration files and self-modifying code deleted>

>>3) Write to the PRG file. Best of all since you need it to
>>run his program!!
>
>No offense, but I really think this is a "sleazy hack".  What's the point of 
>doing this?  Then you have to worry about what happens when you 
>(heaven forbid) modify the source code and recompile, thereby changing 
>the size of the executable.  And, as you pointed out, you have to come
>up with some "clever" scheme to make sure you don't clobber something
>useful (like executable code) in your binary.  Whatever you come up
>with will likely be non-portable as well.

I use MicroEMACS 2.19, a small, fast text editor. I wanted to save the
margin settings and a few other characteristics, but having to load a
configuration file (a) slows down program invocation, and (b) provides yet
another opportunity for something to go wrong, i.e., the configuration
file gets lost. 

I remembered an old CP/M communications program called MEX that had the
ability to "clone" itself -- to write a modified version of the running
program back to disk. 

So I whined at Dale Schumacher, who was handling the MicroEMACS
modifications, until I got him to add such a feature. I assume that it
indeed is nonportable, but is set off by #ifdef ATARI_ST in the source
code. I don't know any details about the technique. Perhaps Dale can be
persuaded to describe it.

      Steve Yelvington, up at the lake in Minnesota        
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