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From: decomyn@penguin.uss.tek.com
Newsgroups: comp.lang.pascal
Subject: Re: IMPLEMENT GOTO ACROSS MODULES IN TURBO PASCAL??
Message-ID: <7147@tekgen.BV.TEK.COM>
Date: 7 Jan 91 00:56:41 GMT
References: <25404@adm.brl.mil> <11656@j.cc.purdue.edu>
Sender: news@tekgen.BV.TEK.COM
Reply-To: decomyn@penguin.uss.tek.com (Vergil William de Comyn)
Organization: Tektronix, Inc., Beaverton,  OR.
Lines: 96

In article <11656@j.cc.purdue.edu> zhou@brazil.psych.purdue.edu (Albert Zhou) writes:
>In article <25404@adm.brl.mil> CDCKAB%EMUVM1.BITNET@cunyvm.cuny.edu ( Karl Brendel) writes:
>>In article <11647@j.cc.purdue.edu>, zhou@brazil.psych.purdue.edu
>> (Albert Zhou) wrote:
>>
>>Try reworking your repeat statement so that each statement 1..n has
>>an associated value. Set that value in the subroutine(s). The loop
>>would look something like:

[code example deleted]

>
>However, this only works when the error arises at the second level of the
>structure (suppose the repeat-until statement is at the first level). If 
>the error arises at a deeper level, it will be a long way before going to
>statement n at the first level. Consider the following example:
>
>	statement 2 calls proc1,
>	procedure proc1;
>        begin
>          ...
>	  proc2;
>	  ...
>	end;
>
>        procedure proc2;
>	begin
> 	  ...
> 	  proc3;
>          ...
>	end;
>
>        procedure proc3;   
>	begin
>	  ...
>	  { this statement might cause error so I insert the error processing
>            you suggested}
>          if an error then begin
>            val_flage = n;
>   	    exit;
>	  end;
>	  ...
>	end;
>	 
>	So when the error comes up, it will continue to finish proc2 and
>proc1 before returning to the first level. But any attemp to continue the
>execution of proc2 and proc1 after an error arises will cause problem.

The solution is to test the value of val_flage after each call.  In fact, 
if a procedure might be called from more than one statement, you can
easily test for a change in the flag.  Using your sample as a base, you
could try:

	statement 2 calls proc1,
	procedure proc1;
	var
	  Save_val : flage;  { assumes type "flage" defined earlier }
        begin
          ...
	  Save_val:=val_flage;
	  proc2;
	  if Save_Val<>val_flage then Exit
	  ...
	end;

        procedure proc2;
	var
	  Save_val : flage;  { assumes type "flage" defined earlier }
	begin
 	  ...
	  Save_val:=val_flage;
 	  proc3;
	  if Save_Val<>val_flage then Exit
          ...
	end;

        procedure proc3;   
	var
	begin
	  ...
	  { this statement might cause error so I insert the error processing
            you suggested}
          if an error then begin
            val_flage = n;
   	    exit;
	  end;
	  ...
	end;

Clear enough?

-------------------------------------------------------------------------------
Brendt Hess a.k.a.             | Disclaimer: Opinions?  I don't even work here!
Vergil William de Comyn a.k.a. |-----------------------------------------------
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