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Re: Review of sizeof usage

From: Stefan Fuhrmann <stefan.fuhrmann_at_wandisco.com>
Date: Thu, 13 Aug 2015 10:34:21 +0100

On Tue, Aug 11, 2015 at 4:02 PM, Philip Martin <philip.martin_at_wandisco.com>

> Stefan Fuhrmann <stefan.fuhrmann_at_wandisco.com> writes:
> > way we use sizeof. In my opinion, we should take the
> > size of the created or processed variable instead of its
> > type, i.e.
> >
> > abc_t *v = apr_pcalloc(pool, sizeof(*v));
> > apr_hash_set(hash, key, sizeof(*key), y);
> > z = apr_hash_get(hash, key, sizeof(*key));
> >
> > rather than
> >
> > abc_t *v = apr_pcalloc(pool, sizeof(abc_t));
> > apr_hash_set(hash, key, sizeof(key_t), y);
> > z = apr_hash_get(hash, key, sizeof(key_t));
> We have had problems with both styles in the past, so neither is immune
> to bugs.

Absolutely, neither way is foolproof. The variable-based
variant is prone to using the wrong level of indirection,
for instance.

Once the code has been debugged, though, the variable-
based variant should have better maintainability because
it is closer to the single point of definition principle. And
I found that usage easier to verify during my review.

> I prefer the explicit type as it is easier to grep.

What do you grep for, specifically? The type should
already show up for the variable / function argument
declaration - so, you should not miss a type usage
either way.

-- Stefan^2.
Received on 2015-08-13 16:51:48 CEST

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