Re: ABI breakage

On Wed, Mar 23, 2005 at 10:10:23PM +0000, Philip Martin wrote:
> "Peter N. Lundblad" <peter@famlundblad.se> writes:
>
> > Yeah, and then I think we can safely extend the struct.
>
> Depends on your definition of safe, it is an ABI change and it is
> trivial to write code that will be broken.

IMO, changes to public structures' sizes is an ABI change. They should not
be changed except across major version revisions.

Labelling a structure explicitly as "may change in size, use foo_create()"
to instantiate it" might be acceptable. IOW, you're removing sizeof() from
the public interface.

In the specific situation, I would say that we *are* changing the ABI. But
we might want to simply accept the risk of breakage out there and change
the ABI to "remove" the structure size from the ABI.

Cheers,
-g

-- 
Greg Stein, http://www.lyra.org/
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