System.pas module_(re)

Sun, 20 Oct 1996 14:40:57 +0100 (MET)

Hello Berend, hello everybody!

The system.pas module triggers one bug in GPC concerning
String schemas as parameters:

> procedure GetDir(D: byte; var s: string);

declares a string schema without specified length as a formal
parameter.  When trying to use it with an actual parameter
which must have a specified length, the compiler crashes.

To work around, always specify string length, e.g.

  procedure GetDir(D: byte; var s: string255);

According to Berend de Boer:
>   This program is free software; you can redistribute it and/or modify
>   it under the terms of the GNU General Public License as published by
>   the Free Software Foundation; either version 2 of the License, or
>   (at your option) any later version.

Berend, you know that the normal GNU GPL implies that a program
linked with your module automatically becomes free software?
If you want to enable commercial use of your module, either state
explicitely that the above does *not* hold, or use the GNU LGPL
(GNU Library General Public License) instead of the normal GPL.

> type
>   shortint = __byte__ integer;
>   byte	   =  __byte__  integer;

That's incompatible with Borland's definition of "byte".
They have

    byte = __unsigned__ shortint;

Same holds for "word".

>   TChar	   = array[0..MaxInt] of char;
>   PChar	   = TChar;
>   pointer  = void;

It must be

    PChar   = ^TChar;
    pointer = ^void;

with adaptions below when "PChar" is used.
On my machine, your module compiled (?!;), but "GetDir"
always returned empty strings for this reason.

>   string255= string(255);
> 
> var
>   {?ExitProc: Pointer;	{ Exit procedure }

Can be implemented using "to end do" and GPC's pointers to procedures.

> export
>   System = (shortint, byte, word, longint, PChar, pointer, string255,
> 	    HeapError, ExitCode, PrefixSeg,
>           Assign, BPChDir => ChDir, Close, Copy, Dec, Delete, Erase,
> 	    GetDir, GetMem,
>	    Inc, IOResult,
>	    MaxAvail, MemAvail, BPMkDir => MkDir,
>           ParamCount, ParamStr,
>	    BPRename => Rename, BPRmDir => RmDir,
>	    UpCase);

"Inc", "dec", "GetMem" are in GPC (and couldn't be implemented in a 
module anyway) - and there is no implementation of them in the body.

Yours,

    Peter

      e-mail:  peter.gerwinski@uni-essen.de
home address:  D\"usseldorfer Str. 35, 45145 Essen, Germany
         WWW:  http://agnes.dida.physik.uni-essen.de/~peter/

Peter Gerwinski (peter@agnes.dida.physik.uni-essen.de)