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From: news@cit-vax.UUCP
Newsgroups: comp.lang.c++
Subject: Re: ANSI C & C++ idea
Message-ID: <1857@cit-vax.Caltech.Edu>
Date: Wed, 25-Feb-87 01:34:38 EST
Article-I.D.: cit-vax.1857
Posted: Wed Feb 25 01:34:38 1987
Date-Received: Fri, 27-Feb-87 06:01:22 EST
References: <17516@ucbvax.BERKELEY.EDU>
Reply-To: jon@oddhack.UUCP (Jon Leech)
Organization: California Institute of Technology
Lines: 27

Organization : California Institute of Technology
Keywords: ANSI, C, C++, idea
From: jon@oddhack.Caltech.Edu (Jon Leech)
Path: oddhack!jon

In article <17516@ucbvax.BERKELEY.EDU> serge@ucbvax.BERKELEY.EDU (serge) writes:
>[]
>    I would like to propose the following notation (valid only in function
>argument declarations/definitions)
>
>	void	f(return Type *t)
>
>to mean that f() will only write the value pointed to by t, and not read it.

	What's your motivation for doing this? I.e. what kind of 
optimizations can a compiler make based solely on knowing that a variable 
is 'write-only'? 

	One difference I see from 'const' is that the 'const' attribute
may actually be enforced by the hardware as opposed to being a semantic 
abstraction. Perhaps MMUs that enforce write-only memory exist (the VAX
doesn't seem to based on a quick perusal of the architecture handbook), 
but what do you use it for?

    -- Jon Leech (jon@csvax.caltech.edu || ...seismo!cit-vax!jon)
    Caltech Computer Science Graphics Group
    __@/