NetNews Usenet Archive 1992 #18/NN_1992_18.iso/spool/comp/lang/cplus/12678

Internet Message Format | 1992-08-20 | 1.6 KB

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From: [e-mail] (Andrew Koenig)
Newsgroups: comp.lang.c++
Subject: Re: Proposal: auto T&
Message-ID: <[e-mail]>
Date: 20 Aug 92 13:06:34 GMT
Article-I.D.: alice.23494
References: <[e-mail]>
Reply-To: [e-mail] ()
Organization: AT&T Bell Laboratories, Murray Hill NJ
Lines: 33

In article <[e-mail]> [e-mail] (Eric Smith) writes:

> Much recent discussion about destruction of temporaries suggests a
> better way to solve the whole problem, and to allow returning references
> to temporaries from functions.

> auto String& stringfunction(const String& input)
> {
>    // Calculate/create a new temporary or named automatic String
>    // and return a reference to it.
> }

> The "auto" in the function return value type tells the compiler to allocate
> the space for that automatic in the stack frame of the caller, instead of
> the stack frame of the called function.

What's wrong with this?

    String stringfunction(const String& input)
    {
       // Calculate/create a new temporary or named automatic String
       // and return a copy of it.
    }

A smart compiler will allocate space for the result in the stack frame of the
caller, instead of the stack frame of the called function.  A number of
C++ implementations already do this.

This technique has the advantage of being easy to understand and
getting the right answer from all existing C++ implementations.
--
                --Andrew Koenig
                  [e-mail]