Eric Blake <ebl...@redhat.com> writes:
> On 09/23/2015 03:43 AM, Markus Armbruster wrote:
>
>>> Commit 1e6c1616 was where we quit burning the C member name 'base'.
>>> Prior to that time, members of base classes did not clash with variant
>>> names because of the C boxing.
>>
>> For union types. For struct types, we still box the base. I'd like to
>> get rid of that.
>
> Patch 34/46 :)
Okay :)
>> Even when the base is boxed, the members still clash in QMP.
>>
>> We also box the variants (e.g. UserDefA *value1 in the example above).
>> Would be nice to get rid of that, too.
>
> What do you mean? Here's an example of current boxed code:
>
> enum EnumType {
> ENUM_TYPE_ONE,
> ENUM_TYPE_TWO,
> };
> struct One {
> int a;
> };
> struct Two {
> char *a;
> };
> struct Union {
> EnumType type;
> /* union tag is @type */
> union {
> One *one;
> Two *two;
> };
> };
>
> Is this what you envision for unboxed? Note that we still have to
> namespace things properly (we have to have union.one.a and union.two.a,
> and not a direct union.a), so all we'd be saving is the additional
> allocation of the variant pointers.
>
> struct Union {
> EnumType type;
> /* union tag is @type */
> union {
> struct {
> int a;
> } one;
> struct {
> char *a;
> } two;
> };
> };
>
> However, I'm not sure it would always help. The conversion of
> netdev_add to full qapi relies on being able to access the variant
> through a named struct (such as NetdevTapOptions); unboxing the variant
> would get rid of the convenient access to these named sub-structs.
struct Union {
EnumType type;
/* union tag is @type */
union {
One one;
Two two;
};
};
For base, we go one step further and peel off the struct, to save some
notational overhead. Pointless for unions.
