Am 21.05.2014 um 09:46 hat Markus Armbruster geschrieben:
> Fam Zheng <f...@redhat.com> writes:
>
> > On Wed, 05/21 07:54, Markus Armbruster wrote:
> >> Fam Zheng <f...@redhat.com> writes:
> >>
> >> > On Tue, 05/20 13:13, Eric Blake wrote:
> >> >> On 05/20/2014 03:07 AM, Fam Zheng wrote:
> >> >> > Please first take a look at patch 7 to see what is supported by this
> >> >> > series.
> >> >> >
> >> >> > Patch 1 ~ 3 allows some useful basic types in schema.
> >> >> >
> >> >> > Patch 4 ~ 6 implements the new syntax.
> >> >> >
> >> >> > Note: The introduced '@arg' sigil, just like the preexisting '*arg',
> >> >> > is
> >> >> > reducing the cleanness of the syntax. We should get rid of both of
> >> >> > them in long
> >> >> > term. Here, this series compromises on this and introduces '@arg'
> >> >> > because:
> >> >> >
> >> >> > - We have to distinguish the argument property dictionary from
> >> >> > nested struct:
> >> >> >
> >> >> > I.e.:
> >> >> >
> >> >> > 'data': {
> >> >> > 'arg1': { 'member1': 'int', 'member2': 'str' }
> >> >> > '@arg2': { 'type': 'int', 'default': 100 }
> >> >> > }
> >> >> >
> >> >> > Until we completely drop and forbid the 'arg1' nested struct use
> >> >> > case.
> >> >> >
> >> >> > - Forbidding 'arg1' it's doable, but doing it now means we pull in
> >> >> > many
> >> >> > distractive patches to this series.
> >> >>
> >> >> Question - since we WANT to get rid of nested struct, why not reverse
> >> >> the sense? Mark all existing nested structs (weren't there just three
> >> >> that we found?) with the '@' sigil, and let the new syntax be
> >> >> sigil-free. Then when we clean up the nesting, we are also getting rid
> >> >> of the bad syntax, plus the sigil gives us something to search for in
> >> >> knowing how much to clean up. But if you stick the sigil on the new
> >> >> code, instead of the obsolete code, then as more and more places in the
> >> >> schema use defaults, it gets harder and harder to remove the use of the
> >> >> sigil even if the nested structs are eventually removed.
> >> >>
> >> >
> >> > It makes not much difference I can see. The hard part is actaully
> >> > dropping
> >> > nested, converting from sigil <-> non-sigil is easy. Of course, nothing
> >> > is
> >> > seriously hard, there are only three nested structs plus some more
> >> > qapi-schema
> >> > test code.
> >>
> >> Adding three ugly sigils and making everybody include one when they add
> >> a nested struct feels much better to me than ugly sigils all over the
> >> place.
> >
> > Well, I could use some background here. Why did we introduce nested
> > structure
> > in the first place?
>
> Because we could?
>
> Felt like a good idea at the time?
>
> I quick glance at commit 0f923be and fb3182c suggests they have been
> supported since the beginning. There is no design rationale.
Let me extend Fam's question: Why don't we simply remove them right
now? If it's really only three instances, converting them to full
types should be a matter of five minutes.
Kevin
