[systemd-devel] [PATCH] libsystemd-bus: Clean up code

[Lennart Poettering]

On Tue, 10.12.13 05:24, Zbigniew Jędrzejewski-Szmek (zbyszek at in.waw.pl) wrote:

> On Mon, Dec 09, 2013 at 09:22:43PM +0100, Thomas H.P. Andersen wrote:
> > If I understood correctly then the assert_return was meant to be used
> > only on the public library functions. I can't seem to find the
> > reference to it so maybe I am wrong though.
>
> There's no strong reason to limit usage to public functions. It's just
> a simple macro really.

It's actually more complicated than that. The macro uses _unlikely_(),
which only should be used when we know that something is really really
unlikely. For assert()-style checks we know that thigns are unlikely,
since they are used to detect programming errors only, not runtime
errors.

hence: please use assert_return() only for checks where normally an
assert() would be appropriate too, but where this would be too
unfriendly because it's in user-facing API. It's about being forgiving
to programming errors by users of our code, but not to ourselves.

To underline this I have now updated assert_return() to also log the
failing condition as LOG_DEBUG, since that sounds like a good idea so
that programming errors can be easily tracked.

So again: please do not replace if checks blindly by
assert_return(). Use assert_return() only to detect programming errors
in user code, which means only really to check parameters of public API
calls. Use assert() in internal code for the same purpose.

I also updated CODING_STYLE a bit to explain this.

Lennart

-- 
Lennart Poettering, Red Hat