Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uflorida!gatech!gitpyr!dsking
From: dsking@pyr.gatech.EDU ( David King)
Newsgroups: comp.sys.amiga.tech
Subject: M2/C discussion (Re: Can you nest subroutines in C?)
Message-ID: <8673@pyr.gatech.EDU>
Date: 5 Jul 89 02:53:08 GMT
References: <4524@crash.cts.com> <18213@usc.edu>
Reply-To: dsking@pyr.UUCP ( David King)
Organization: Georgia Institute of Technology
Lines: 70

In article <18213@usc.edu> papa@pollux.usc.edu (Marco Papa) writes:
>I've been told by a third party the this is not entirely true. Can you have 
>procedure pointers as fields of data structure as in:
>
>struct xpr {
>	long (*xpr_open)();
>	long (*xpr_close)();
>	....
>}
>
>...
>struct xpr *io;
>
>io->xpr_open = MyOpen;
>io->xpr_close = MyClose;
>
>Can you do that in M2?  I'd really like to know? Also does M2 provide
>setjmp/longjmp in one of the libraries?
>

	Yep, you can do that in M2.  Here's the equivalent code:

TYPE xprType = RECORD
		xprOpen,
		xprClose : PROC;
		...
	       END;
...
VAR io : xprType;
...
    WITH io DO
      xprOpen := MyOpen;
      xprClose := MyClose;
    END; (* With *)
...

#ifdef RAMBLE

	I actually use this in my present project (when I have time I'm working
on a very small terminal program since I don't have much free memory) to have 
all open windows use the same IDCMP port.  Each window's UserData pointer 
references a structure/RECORD of procedure pointers for each type of message.
I use this feature so much I go crazy on ISO pascal compilers.

	setjmp/longjmp?  Its definately not part of the language definition
(they actually aren't part of C's definition unless the ANSI committee added 
it in the last year), and I couldn't find anything like it in M2Sprint's 
definitions.  *jmp actually are library routines on UNIX that got used in 
programs so much that they made it into most C systems.  This brings up 
something I've been wondering - what are things like *jmp useful for in an 
Amiga program?

#endif

	-David
	
>-- Marco Papa 'Doc'
>-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
>uucp:...!pollux!papa       BIX:papa       ARPAnet:pollux!papa@oberon.usc.edu
>"There's Alpha, Beta, Gamma, Diga and Caligari!" -- Rick Unland
>-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
				       ^^^^^^^^
					Slowly the list grows longer.  Is this
a progression towards the "ultimate" customers as debuggers?

-- 
 David King - 	FROM Disclaimers IMPORT Standard;
Georgia Insitute of Technology, Atlanta Georgia, 30332
uucp: ...!{akgua,allegra,amd,hplabs,ihnp4,seismo,ut-ngp}!gatech!gitpyr!dsking
ARPA: dsking@pyr.gatech.edu