Re: cvs commit: src/sys/kern vfs_bio.c vfs_syscalls.c src/sys/sys buf.h src/sys/vm vm_pager.c

[Joerg Sonnenberger <joerg@xxxxxxxxxxxxxxxxx>]

On Wed, Aug 03, 2005 at 08:21:46AM -0700, Matthew Dillon wrote:
> 
> :
> :On Tue, Aug 02, 2005 at 09:59:53PM -0700, Hiten Pandya wrote:
> :>   Localise buffer queue information into kern/vfs_bio.c, it should not be
> :>   messed with outside of the named file.  Convert the QUEUE_* #defines
> :>   into enum bufq_type, prefix the names with 'B'.  The change to initpbuf()
> :>   is acceptable since they are a hack anyway, not to mention that
> :
> :You might want to change the various switch statements to have no
> :default case, allowing GCC to warn about missing cases.
> :
> :Joerg
>     
>     I'd rather not depend on that feature of GCC, it could bite us in some future
>     release of GCC, plus it is not always desireable to actually list all cases
>     in a switch state (though in the buffer cache case its probably fine).
>     A default/panic case is more robust.

The default + panic is not detectable at compile time, that's what I
mean. The requirement is that the type of expression in the switch
statement is an enum, it will warn if any case is missing. That's
standard practise in other languages as well, not only C.

It's not always a good thing, yes, but if you have more than two cases
to handle (and that's why a switch is used after all), it can make the
code more maintainable because you can't just add a new type and forget
to handle it somewhere :-)

Joerg