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SubjectRe: [RFC] [PATCH] C exceptions in kernel
On Sat, Feb 23, 2002 at 06:05:48PM +0200, Dan Aloni wrote:
> But, it CAN be used in *local* driver call branches. Writing a new
> driver? have a lot of local nested calls? Hate goto's? You can use
> exceptions.

Is this really anything other than syntactic sugar? Maybe it's different
in drivers, but I find myself doing the following in user space all the time

#define unless(x) if (!(x)) /* perl/BCPL corrupted me */

function(...)
{
char *foo = 0, *bar = 0;
int locked = 0;
int rc = -1;

if (bad args or something) {
out: if (foo) free(foo);
if (bar) free(bar);
if (locked) unlock();
return (rc);
}

unless (locked = get_the_lock()) goto out;
unless (foo = allocate_foo()) goto out;
unless (bar = allocate_bar()) goto out;

more code....

rc = 0;
goto out;
}

It seems ugly at first but it has some nice attributes:

a) all the cleanup is in one place, for both the error path and the
non-error path. I could put it at the bottom, I like it at the
top because that's where I tend to have the list of things needed
to be cleaned.

b) all the error cases are branches, the normal path is straightline.

c) it's as dense as I can make it.

So how would you do the same thing with exceptions?
--
---
Larry McVoy lm at bitmover.com http://www.bitmover.com/lm
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