Messages in this thread | | | From | Rusty Russell <> | Subject | Re: [PULL] typesafe callbacks for kthread and stop_machine | Date | Fri, 1 Aug 2008 10:39:29 +1000 |
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On Friday 01 August 2008 00:06:43 Andi Kleen wrote: > On Thu, Jul 31, 2008 at 02:52:35PM +1000, Rusty Russell wrote: > > Just the two places I look after. And this time the conglomerate patch > > is included below for more random commentry. > > I must say I personally don't like the wrapper macros that you require > for each function that uses this. A wrapper macro has a large impact > on code readability because everyone following a call chain has > to do an additional grep/open file etc. step. I have my doubts not having > casts outweights that disadvantage.
Yes, but the benefits of using them everywhere is that they do become part of the landscape. "Oh, that's a typesafe callback, OK".
If this were just about neatness, I'd share your doubts. But I want to be able to change the type of a var and have the compiler complain when I hand it to a function which expects the old type. This bit me a few months back, leading to this experiment.
> I know that gcc has this funky transparent union extension that > glibc socket() uses to allow different address types without casts. > It has the advantage of not needing wrapper macros. Any chance of > using that instead? Or has that one been considered already and > discarded?
That's aimed at a slightly different case, where the function knows what types it can get. But that doesn't work for truly generic callbacks: the type is completely controlled by the caller. ie. we want to allow whatever type matches the arg.
Hope that clarifies, Rusty.
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