AW: [mpls-linux-general] coding style of macros

[Georg K. <gk...@gi...>]

Hi,

>
> > here's a macro i came across in the mpls linux code
> >
> > define INIT_LIST_HEAD(ptr) do { \
> >         (ptr)->next = (ptr); (ptr)->prev = (ptr); \
> > } while (0)
> >
> > at the risk of sounding prude,
> > why is it that the initialization statements were enclosed in braces with a
> > while(0) ?
> >
> > couldn't it be simply written as
> >
> > define INIT_LIST_HEAD(ptr)      (ptr)->next = (ptr); (ptr)->prev = (ptr);
>
> Think to something like that:
>
>    if (ptr != NULL)
>       INIT_LIST_HEAD(ptr);
>
> Without the do { ... }while(0) statement, the second instruction would
> be outside the "if".

That's true, but would just braces { .. } be sufficient for that purpose?

Georg