Re: [Question] What is the definition of “private” fields in QOM?

["Daniel P. Berrangé" <berrange@redhat.com>]

On Sun, Oct 20, 2024 at 12:10:14AM +0800, Zhao Liu wrote:
> Hi maintainers and list,
> 
> In the QOM structure, the class and object structs have two members:
> parent_class and parent_obj, which are often marked as "< private >" in
> the comment.
> 
> I couldn’t find information on why to define ‘private’ and ‘public’,
> even in the earliest QOM commits and the patch emails I could find.
> 
> Does ‘private’ refer to the internal implementation code of QOM, or does
> it refer to the specific code that defines and implements this object
> and its class?
> 
> I understand the original idea of private field indicates it cannot be
> accessed directly out of the "private" scope.

I see two scenarios

 * Devices where the structs are in the include/..../<blah>.h

   The private/public comments are a message to other code in QEMU about
   which fields are OK to access directly, and which should not be accessed.


 * Devices where the structs are in the ../<blah>.c

   The private/public comments look entirely pointless, as everything
   is private to the .c file.


99% of the time it seems the "parent" / "parent_obj" fields are the only
one marked private. There are a handful of classes where other fields are
under the private comment, but not many. 

With regards,
Daniel
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