Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!uwm.edu!zaphod.mps.ohio-state.edu!usc!apple!apple.com!rmh
From: rmh@apple.com (Rick Holzgrafe)
Newsgroups: comp.sys.mac.programmer
Subject: Re: How do you execute a CODE resource?
Message-ID: <9750@goofy.Apple.COM>
Date: 14 Aug 90 22:14:06 GMT
Sender: usenet@Apple.COM
Organization: Apple Computer, Inc.
Lines: 30
References:<1990Aug14.003350.2055@vaxa.cc.uwa.oz.au> <1990Aug14.131735.21771@ux1.cso.uiuc.edu> <1348@anaxagoras.ils.nwu.edu>

From C, something like this:

    Handle h;                              /* Handle to resource */
    int (*myFuncPtr) (int arg1, int arg2);    /* Ptr to function */
    int theResult;    /* Save the return value from the function */

    /* Get handle to code resource */
    h = GetResource ('myFN', 128);
    /* Lock it down - Very important! */
    HLock (h);
    /* Get appropriately typed function pointer */
    myFuncPtr = (int (*)(int, int))*h;
    /* Call the function */
    theResult = (*myFuncPtr)(arg1, arg2);

See? You de-reference the handle to get a pointer, and typecast that into 
a pointer to the kind of function you are going to call. Then just call it.

After the call, you can clean up in whatever way is appropriate: release 
the resource, if you don't need it any more; or save the handle but unlock 
it until you need it again, to avoid heap fragmentation.

I don't know how to do this in Pascal, I'm afraid. Hope this helps.

==========================================================================
Rick Holzgrafe              |    {sun,voder,nsc,mtxinu,dual}!apple!rmh
Software Engineer           | AppleLink HOLZGRAFE1          rmh@apple.com
Apple Computer, Inc.        |  "All opinions expressed are mine, and do
20525 Mariani Ave. MS: 3-PK |    not necessarily represent those of my
Cupertino, CA 95014         |        employer, Apple Computer Inc."