On Sat, 2013-03-16 at 11:57 -0400, Steven Rostedt wrote:
> My macro nastiness is contagious ;-)
True.
> On Sat, 2013-03-16 at 06:50 -0700, Joe Perches wrote:
> > +int (seq_printf)(struct seq_file *m, const char *f, ...)
>
> That's rather ugly. Why not just #undef seq_printf before defining it?
The whole thing is ugly, nasty and hackish.
I kinda like it.
But I don't like unnecessary undefs.
The preprocessor doesn't expand (funcname).
> Anyway, not making va_args a whacky name is dangerous. This is why I add
> those crazy underscores. If someone does:
>
> var = 1;
> va_args[] = "abc";
> seq_printf(m, "%d %s", var, va_args);
The same could be true of fmt and it's
used in lots of macros no?
> What will be printed is:
>
> 1 var, va_args
>
> That will be very confusing to people.
And so be fixed very quickly.
> > + if (sizeof(va_args) > 1) \
> > + seq_printf(seq, fmt, ##__VA_ARGS__); \
> > + else \
> > + seq_puts(seq, fmt); \
> > +} while (0)
>
> BTW, you need to return a value.
Oh, yeah, thanks.
> #define seq_printf(seq, fmt, ...) \
> -do { \
> +({ \
> char va_args[] = __stringify(__VA_ARGS__); \
> + int _____ret; \
> if (sizeof(va_args) > 1) \
> - seq_printf(seq, fmt, ##__VA_ARGS__); \
> + _____ret = seq_printf(seq, fmt, ##__VA_ARGS__); \
> else \
> - seq_puts(seq, fmt); \
> -} while (0)
> + _____ret = seq_puts(seq, fmt); \
> + _____ret; \
> +})
It's certainly better as a statement expression,
but I think the underscores are really ugly and
not necessary as ret is locally scoped.
Checkpatch doesn't generally parse strings.
checking strings for % could be done though
I suppose.
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