Messages in this thread | | | Date | Mon, 5 Aug 2002 14:47:02 -0500 (CDT) | From | Kai Germaschewski <> | Subject | Re: driverfs API Updates |
| |
On Mon, 5 Aug 2002, Patrick Mochel wrote:
> [1]: The reason for the macro is because the driverfs internals > have changed enough to be able to support attributes of any type. In > order to do this in a type-safe manner, we have a generic object type > (struct attribute) that we use. We pass this to an intermediate layer > that does a container_of() on that object to obtain the specific > attribute type.
Of course that means that it's not really type-safe, since it has no way to check whether the object is embedded in the right type of struct, right ;) (But I think that's okay, C doesn't have provisions for real inheritance)
> This means the specific attribute types have an embedded struct > attribute in them, making the initializers kinda ugly. I played with > anonymous structs and unions to have something that could > theoretically work, but they apparently don't like named > initializers.
Have you considered just putting in the embedded part via some macro - I think that's what NTFS does for compilers which don't support unnamed structs.
Basically
#define EMB_ATTRIBUTE \ int emb1; int emb2
struct my_attribute { EMB_ATTRIBUTE int my1; int my2; };
That'll work with named initializers just fine, so the users don't have to deal with ugly DEVICE_ATTR macros, where one forgets if parameter #3 was show or store ;) - It follows the common way of hiding away unavoidable ugliness in some header.
> [2]: I wanted to consolidate the first two parameters, but I couldn't > find a way to stringify ##name (or un-stringify "strname"). Is that > even possible?
Why would stringify (include/linux/stringify.h) not work? However, Al Viro may get mad at you for generating ungreppable symbols either way ;-)
--Kai
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |