Re: kernel coding style for if ... else which cross #ifdef

[H. Peter Anvin]

Jeremy Fitzhardinge wrote:
> Tom Spink wrote:
> > A thought occurred to me that we may be able to used some preprocessor
> > magic and do this:
> >
> > #define config_defined(x) CFGVAL_## x
> >
> > Which means that, if we get Kconfig to produce:
> >
> > #define CFGVAL_CONFIG_FOO 0
> > #define CFGVAL_CONFIG_VALUE_BAR 1
> > #define CFGVAL_CONFIG_VALUE_BAZ_MODULE 1
> >
> > We can use this:
> >
> > if (config_defined(CONFIG_FOO) && some_expr) {
> >    panic("Oh no.");
> > }
>
> Well, in that case you could use Willy's magic hack:
>
> #define config_defined(x)      (x - 0)
>
> Which isn't a bad alternative to defining a whole pile of new symbols...

That can *strongly* be argued with.

In particular, the use of #ifdef is crap to begin with.  Using #if even 
for the preprocessor makes it possible to trap misspellings.

	-hpa
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