Re: [Qemu-devel] [PATCH RFC 0/2] QMP command qom-new

["Andreas Färber" <afaerber@suse.de>]

Am 24.05.2012 16:08, schrieb Markus Armbruster:
> Andreas Färber <afaerber@suse.de> writes:
> 
>> Am 24.05.2012 13:43, schrieb Markus Armbruster:
>>> Beware: second patch is the product of voodoo-coding.
>>
>> Hm, I don't like the voodoo. ;) I would rather expose a proper C API
>> like object_try_new(const char *, Error **) than opening up the TypeImpl
>> internals to the public and hand-coding it everywhere.
> 
> How does returning a TypeImpl * open up TypeImpl any more than
> type_register() already does?

type_register[_static]() operates on TypeInfo, not TypeImpl.

I consider TypeImpl an implementation detail of qom/object.c, but maybe
I'm mistaken.

>> similar error-catching scenario where I needed to check for class
>> existence in some qdev_try_* function.
> 
> If this is a really common pattern, and object_try_new() really saves
> code, why not.
> 
> Can't see why we need the Error **argument, though.  What kinds of
> different errors that do you envisage?  Where "different" means "actual
> callers care about the difference".

Well, I thought of class-doesn't-exist vs. out-of-memory. It would just
be to report different textual messages to the end user - as QMP error
response or as stderr output elsewhere. I have better OOM handling
somewhere down my TODO list, including a preallocated Error object. Main
reason is avoiding code duplication though.

Andreas

-- 
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer; HRB 16746 AG Nürnberg