Path: utzoo!attcan!uunet!oddjob!uwvax!husc6!ukma!psuvm.bitnet!gfx
From: GFX@PSUVM.BITNET
Newsgroups: comp.sys.mac.hypercard
Subject: Re: A good book for desscribing nitty gritty of XCMDs and language use
Message-ID: <43294GFX@PSUVM>
Date: 25 May 88 04:02:41 GMT
References: <50895@sun.uucp> <4015@zodiac.UUCP> <10899@apple.Apple.Com>
Distribution: comp
Organization: The Pennsylvania State University - Computation Center
Lines: 47

>There is no REALLY good book on XCMD writing.  The best current source
>is APDA.  There is a disk with some sample XCMDs in C and Pascal with a
>bit of brief on-disk documentation.

I have been introduced to XCMDs syntax by the XCMD.SIT available from
Borland's forum.  The examples provided are relatively clear, except
for the correct procedure one should use to pass arrays, instead of
single parameters to XFCNs.

Which source would be the most appropriate and how do we get it?  Eg. ->
I have been especially puzzled by the following:

PROGRAM test;

 $R-
 $U-
 $D PasXFCN

USES   MemTypes, QuickDraw, OSIntf, HyperXCmd;

  PROCEDURE PasXFCN(paramPtr:#XCmdPtr);     (* THE # SHOULD READ AS A CARET *)

   VAR
    str    : Str255;

 $I Xcmdglue.Inc

   BEGIN;
    zeroToPas(paramPtr#.params[2]#,str);    (* THE # SHOULD READ AS CARET *)
    paramPtr#.returnValue := PasToZero(str);(* THE # SHOULD READ AS CARET *)
   END;

BEGIN
END.

If called with:       Put test(1,2) into someContainer
the XFCN returns 2, as expected.  However, if the string 1,2 is in a container,
a call such as:       Put test(field someField) into someOtherContainer
returns garbage of the form :  W>>W>>W>> (etc.)

What happens?  Can someone tell me how to transfer arrays residing in
HYPERCARD fields to an XFCN, and back?
-------

Stephane Gauvin : GFX@PSUVM : (814) 237-4979 : Compuserve 73057,1763
Interests: Marketing: New products, Mathematical Models, Game Theory
           Computing: AI, MacIntosh, Hypercard