Path: utzoo!attcan!uunet!lll-winken!lll-lcc!ames!pasteur!ucbvax!MITRE-BEDFORD.ARPA!dee%linus
From: dee%linus@MITRE-BEDFORD.ARPA (David E. Emery)
Newsgroups: comp.lang.ada
Subject: Re: Dynamic Address Clauses??
Message-ID: <8806161353.AA17815@linus.MENET>
Date: 16 Jun 88 13:53:12 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 34

Here's a very legitimate use for a dynamic address clause: C often
returns addresses of objects (becaues C functions cannot return
structures).  The following should be perfectly legal AND ACCEPTABLE
(i.e.  compilers should support this):

	Ada				C 
	
	type rec is record		struct rec {
	  foo : integer;		    int foo;
	  bar : integer;		    int bar;
	end record;			};

					rec *getstuff();

	function getstuff
	    return system.address;
	pragma interface (C, getstuff);

	declare
	  myrec : rec;
	  for myrec use at getstuff;
		-- function call returns system.address.
	  fooval, barval : integer;
	begin
	  fooval := myrec.foo;
	  barval := myrec.bar;
	end;


Obviously, if address clauses were restricted to be static, this
wouldn't work.  They're not, so this should be just fine.  I've tried
this technique on Verdix/Sun, and it works just fine.

				dave emery
				emery@mitre-bedford.arpa