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From: jgk@panix.com (Joe keane)
Newsgroups: comp.compilers
Subject: Re: Looking for volunteers for XL
Date: Tue, 13 Dec 2011 00:08:53 +0000 (UTC)
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Keywords: design, syntax,macros
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Xref: x330-a1.tempe.blueboxinc.net comp.compilers:389


Kaz Kylheku <kaz@kylheku.com> wrote:
>For one thing, any syntactic unit that contains declarations cannot be
>an expression that returns a value. Macros that need to generate
>complex code that requires hidden variables automatically have a
>difficulty in returning a value in a function-call-like way, because
>only expressions do that.

That is valid, but it's not not-difficulty work-around-ed.

#2. Don't use function-like macros.

Make the result one of the parameters (unless it is really simple, then
some day in the future your 'really simple' macro is not so really
simple).

e.g.

    #define GET_FORDO_BIT(FOP) \
    ...

    int f(int x)
    {
	...
	if (GETFORDO_BIT(fop))
	{
	    ...
	}
	...
    }

versus

    #define GET_FORDO_BIT(FOP, FOB) \
    ...

    int f(int x)
    {
	...
	GET_FORDO_BIT(fop, fob);
	if (fob)
	{
	    ...
	}
	...
    }

How hard is that?