Legal Change in GPC ?_(re)

Mon, 28 Apr 1997 16:54:20 +0200 (MET DST)

According to Christian Wendt:
> 
> I wondered how to implement the ability to change colours and write text  
> to Standard output - but I think it's nearly impossible to do this within  
> a Unit - the C - Textcolor doesn't work with the fprintf function that is  
> used in the RTS... 

Nevertheless I did this.  :-)  Please have a look at the BPcompat package,
available in the `contrib' subdirectory of the GPC distribution.

> I wondered wether it would be legal (in sense of  
> portability and compability...) to change the RTS : Textcolor works if you  
> check wether the file passed to writeln is Stdout - when it is you use  
> cprintf (or putch instead of fwrite).

You are right that this is a problem we must think about.  In this case
I think it increases portability and compatibility to do the changes
because otherwise it is impossible to get colors under DOS whereas you
can have them with Linux or any other system which provides colors as
terminal escape sequences, e.g. according to ANSI.

> The question is - would it be legal to do such - you could put in a  
> variable (smth like "GPC_ConsoleOutput") to switch in on/off ?

In the BPcompat package or in newer Alpha releases of GPC, this variable
exists and is called `p_directvideo', available as `DirectVideo' if you
do `uses CRT'.  If it is `true', `writeln' is performed through `cprintf',
otherwise through `printf'.

Greetings,

    Peter

  Dipl.-Phys. Peter Gerwinski, Essen, Germany, free physicist and programmer
peter.gerwinski@uni-essen.de - http://home.pages.de/~peter.gerwinski/ [970201]
 maintainer GNU Pascal [970420] - http://home.pages.de/~gnu-pascal/ [970125]

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