On Thu, 2010-11-18 at 09:34 +0100, Ingo Molnar wrote: > * H. Peter Anvin <[email protected]> wrote: > > > On 11/14/2010 11:02 PM, Ingo Molnar wrote: > > > > > > * H. Peter Anvin <[email protected]> wrote: > > > > > >> What? What is wrong with static variables in functions? It really > > >> doesn't seem > > >> to be a good idea to make them file-scope if they don't need to be. > > > > > > They are very easy to overlook and mix up with regular stack variables > > > and i've seen > > > (and introduced myself) a number of bugs due to them. > > > > > > They also often are used in buggy ways (with SMP not taken into > > > consideration), so > > > overlooking them during review compounds their negative effects. Putting > > > them in > > > front of the function isnt a big deal in exchange. > > > > > > There are people who never overlook them (like yourself), but my brain is > > > wired up > > > differently. > > > > > > > However, I have to vehemently object to putting them in a wider scope > > than is otherwise necessary. I agree that static variables should be > > used sparsely if at all (there really are vary few uses of them that are > > valid), but putting them in a larger scope screams "I'm used in more > > than one function", and that is *not* a good thing. > > That's why we sometimes use the (imperfect) compromise to put them in front > of that > function, not at the top of the file. > > Look at the general balance of hardship: very little harm is done (it's not a > big > deal if a variable is only used in a single function) but having it with > local > variables can be _really_ harmful - for example i overlooked them when i > reviewed > this patch. I dont like important details obscured - i like them to be > apparent. > Again, this is something that some people can parse immediately on the visual > level > - me and many others cannot.
What about:
int foo(void)
{
static int bar;
struct thing_struct *thing;
int other_var;
char *p;
...
}
I think the visual wrongness of that formatting would be enough for me
to stop and look twice. Though I guess it doesn't work if you have few,
or no other variables other than the statics to declare.
cheers
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