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From: beard@ux1.lbl.gov (Patrick C Beard)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Dereferencing ProcPtr in LS Pascal
Message-ID: <4771@helios.ee.lbl.gov>
Date: 5 Feb 90 01:13:09 GMT
References: <1268@diemen.cc.utas.oz> <1990Feb4.202759.16223@Neon.Stanford.EDU>
Sender: usenet@helios.ee.lbl.gov
Reply-To: beard@ux1.lbl.gov (Patrick C Beard)
Organization: Lawrence Berkeley Laboratory, Berkeley
Lines: 38
X-Local-Date: 4 Feb 90 17:13:09 PST

In article <1990Feb4.202759.16223@Neon.Stanford.EDU> philip@pescadero.stanford.edu writes:
#In article <1268@diemen.cc.utas.oz> brian Harrold writes:
#>
#>    I have a procedure in which one of the parameters is of type
#>    ProcPtr (pointer to another procedure). Is there any way in
#>    LS Pascal to dereference the pointer to the given procedure,
#>    and execute it ?
#>
#
#The solution is along the following lines:
#
#procedure callProc(** parameters exactly as in proc ** ; theProc:
#procPtr);
#inline $205F $4ED0 ;  {check the syntax for inline in LS manual}
#

By the way, MPW C++ will allow you to declare procedure pointer
types and call them directly by pointer, even when declared
as pascal!  THINK C doesn't let you do that...

For example:

typedef pascal OSErr (**GMProcHandle)(type1 arg1, type2 arg2, ...);

This type lets you call a code resource that has a funny calling convention.

	GMProcHandle myProcHandle = (GMProcHandle)GetResource(myId, 'ADgm');
	...
	HLock((Handle)myProcHandle);
	OSErr result = (**myProcHandle)(...);

Sure looks nice to me, don't have to do any of that funny inline code.


-------------------------------------------------------------------------------
-  Patrick Beard, Macintosh Programmer                        (beard@lbl.gov) -
-  Berkeley Systems, Inc.  ".......<dead air>.......Good day!" - Paul Harvey  -
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