Re: [Qemu-devel] [PATCH 01/27] qom: add the base Object class

[Anthony Liguori <anthony@codemonkey.ws>]

On 01/02/2012 05:01 PM, Andreas Färber wrote:
> Am 22.12.2011 20:57, schrieb Anthony Liguori:
>> On 12/22/2011 12:00 PM, Kevin O'Connor wrote:
>>> On Thu, Dec 22, 2011 at 11:41:08AM -0600, Anthony Liguori wrote:
>>>> On 12/22/2011 11:25 AM, Kevin O'Connor wrote:
>>>>> Why not declare types with something like the following:
>>>>>
>>>>> TypeInfo my_device_info = {
>>>>>       .name = "my-device",
>>>>>       .parentinfo =&device_info,
>>>>>       .instance_size = sizeof(MyDevice),
>>>>> };
>>>>>
>>>>> That is, instead of looking up the TypeImpl via a string, lookup the
>>>>> TypeImpl via the address of the TypeInfo.  (Or possibly store a
>>>>> pointer to TypeImpl in TypeInfo during registration.)
> [...]
>> Yes, thinking about it, I think you're correct that .parent could refer
>> to some sort of type handle.
>>
>> But I think it's a bit nicer to have a string identify the parent type
>> than an extern struct.  I guess it's more a matter of taste than
>> anything else :-)
>
> The advantage of using some kind of symbolic name is that the compiler
> helps us avoid typos. If we use strings, we defer the checking to the
> actual instantiation at runtime.

That's why I use #define's to make a symbol for the types.  The only reason 
that's not done universally is it would be a bit challenging to script the 
conversion to do that (I though I did attempt it a couple times).

Regards,

Anthony Liguori

>
> Andreas
>