Re: [Qemu-devel] [PATCH 5/9] QemuOpts: Convert qemu_opts_foreach() to Error

[Paolo Bonzini]

On 02/06/2015 14:34, Eric Blake wrote:
> Or, you could do:
> 
> if (!errp) { errp = &error_abort; } ... if (rc) { return rc; } 
> assert(!*errp);
> 
> and not have to use error_propagate() - either the caller is
> tracking errors, or the caller passed NULL because they are
> tracking return value and we can assume that their callback will
> not raise errors (even on negative returns).  But that's a slightly
> different contract.
> 
> You're right that the possibility of NULL makes it not as trivial
> as I first thought, so I'm starting to waffle on whether enforcing
> the contract is worth the extra lines of code.  Anyone else with an
> opinion?

I think the simplest code is the best. :)  Our error propagation
at last works surprisingly well, but can already be pretty heavy on
boilerplate...

Paolo