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Date: Fri, 23 May 2014 19:13:42 +0200
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Subject: Re: [Qemu-devel] [PATCH v2 0/4] Allow QOM struct fields to be
	marked as private
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: QEMU Developers <qemu-devel@nongnu.org>, =?UTF-8?B?QW5kcmVhcyBGw6RyYmVy?= <afaerber@suse.de>, Anthony Liguori <aliguori@amazon.com>, Patch Tracking <patches@linaro.org>

Il 23/05/2014 18:21, Peter Maydell ha scritto:
> On 23 May 2014 15:33, Paolo Bonzini <pbonzini@redhat.com> wrote:
>> Il 23/05/2014 13:50, Peter Maydell ha scritto:
>>> On 23 May 2014 12:23, Andreas Färber <afaerber@suse.de> wrote:
>>>> Am 23.05.2014 13:13, schrieb Peter Maydell:
>>>>> Ping?
>>>>
>>>> I believe I remarked that in the example
>>>> typedef struct Foo {
>>>> would be more in line with our Coding Style and majority of users.
>>>>
>>>> Other than that, I have no objections and assumed you'll take it through
>>>> your arm queue.
>>>
>>> Oops, yes, I'd forgotten that conversation. I'll remove
>>> the newline preceding the '{' and am happy to put this
>>> through the target-arm queue.
>>
>> Semi-serious proposal:
>>
>>     #define comma_if_empty_ ,
>>     #define CPP_IFEMPTY(macro, t, f)      CPP_IFEMPTY1(macro, t, f)
>>     #define CPP_IFEMPTY1(value, t, f)     CPP_IF2(comma_if_empty_##value, t, f)
>>     #define CPP_IF2(comma_if_true, t, f)  CPP_IF3(comma_if_true t, f)
>>     #define CPP_IF3(_, v, ...) v
>>
>>     #define qom_private(macro) CPP_IFEMPTY(IMPLEMENTING_##macro,, QEMU_PRIVATE_ATTR)
>>
>> To be used as:
>>
>>     qom_private(A9_SCU) MemoryRegion iomem;
>
> Interesting. That means we can avoid the irritating
> boilerplate in each include file to define and undefine
> qom_private, at the cost of the tag on each field in the
> struct being a bit longer. I'm not entirely sure which
> I prefer...

You could also

#define a9_scu_private qom_private(A9_SCU)

    a9_scu_private MemoryRegion iommu;

where the difference becomes a wash.

Paolo