Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!uunet!hsi!mfci!karzes
From: karzes@mfci.UUCP (Tom Karzes)
Newsgroups: comp.lang.c
Subject: Re: syntax for unary assignment operators (was Re: C history question)
Keywords: C design, XOR
Message-ID: <1032@m3.mfci.UUCP>
Date: 18 Sep 89 19:49:25 GMT
References: <575@calmasd.Prime.COM> <1687@sunset.MATH.UCLA.EDU> <174@cpsolv.UUCP> <1989Sep17.150504.16643@jarvis.csri.toronto.edu>
Sender: karzes@mfci.UUCP
Reply-To: karzes@mfci.UUCP (Tom Karzes)
Organization: Multiflow Computer Inc., Branford Ct. 06405
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In article <1989Sep17.150504.16643@jarvis.csri.toronto.edu> flaps@dgp.toronto.edu (Alan J Rosenthal) writes:
>A somewhat consistent but fairly bizarre syntax would be
>	x -=;
>
>The analogy to x -= y is that
>	x fn= y;
>expands to
>	x = fn(x, y);
>so
>	x fn=;
>expands to
>	x = fn(x);

The problem with this is that you would like it to have the same precedence
as ++ and --.  This causes the following:

    a -= * b

to be parsed as:

    (a -=) * b

rather than:

    a -= (* b)

which is the current correct parse (and which should remain the correct
parse).  You'd have to introduce a new operator to make this work reasonably.