Re: [Qemu-devel] [PATCH 03/23] qom: add helper macro DEFINE_TYPES()

[David Gibson <david@gibson.dropbear.id.au>]

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On Thu, Oct 05, 2017 at 06:24:30PM +0200, Igor Mammedov wrote:
> DEFINE_TYPES() will help to simplify following routine patterns:
> 
>  static void foo_register_types(void)
>  {
>     type_register_static(&foo1_type_info);
>     type_register_static(&foo2_type_info);
>     ...
>  }
> 
>  type_init(foo_register_types)
> 
> or
> 
>  static void foo_register_types(void)
>  {
>     int i;
> 
>     for (i = 0; i < ARRAY_SIZE(type_infos); i++) {
>         type_register_static(&type_infos[i]);
>     }
>  }
> 
>  type_init(foo_register_types)
> 
> with a single line
> 
>  DEFINE_TYPES(type_infos)
> 
> where types have static definition which could be consolidated in
> a single array of TypeInfo structures.
> It saves us ~6-10LOC per use case and would help to replace
> imperative foo_register_types() there with declarative style of
> type registration.
> 
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

> ---
>  include/qom/object.h | 36 ++++++++++++++++++++++++++++++++++++
>  1 file changed, 36 insertions(+)
> 
> diff --git a/include/qom/object.h b/include/qom/object.h
> index 9a2369c..dc73d59 100644
> --- a/include/qom/object.h
> +++ b/include/qom/object.h
> @@ -79,6 +79,28 @@ typedef struct InterfaceInfo InterfaceInfo;
>   * #TypeInfo describes information about the type including what it inherits
>   * from, the instance and class size, and constructor/destructor hooks.
>   *
> + * Alternatively several static types could be registered using helper macro
> + * DEFINE_TYPES()
> + *
> + * <example>
> + *   <programlisting>
> + * static const TypeInfo device_types_info[] = {
> + *     {
> + *         .name = TYPE_MY_DEVICE_A,
> + *         .parent = TYPE_DEVICE,
> + *         .instance_size = sizeof(MyDeviceA),
> + *     },
> + *     {
> + *         .name = TYPE_MY_DEVICE_B,
> + *         .parent = TYPE_DEVICE,
> + *         .instance_size = sizeof(MyDeviceB),
> + *     },
> + * };
> + *
> + * DEFINE_TYPES(device_types_info)
> + *   </programlisting>
> + * </example>
> + *
>   * Every type has an #ObjectClass associated with it.  #ObjectClass derivatives
>   * are instantiated dynamically but there is only ever one instance for any
>   * given type.  The #ObjectClass typically holds a table of function pointers
> @@ -799,6 +821,20 @@ Type type_register(const TypeInfo *info);
>  void type_register_static_array(const TypeInfo *infos, int nr_infos);
>  
>  /**
> + * DEFINE_TYPES:
> + * @type_array: The array containing #TypeInfo structures to register
> + *
> + * @type_array should be static constant that exists for the life time
> + * that the type is registered.
> + */
> +#define DEFINE_TYPES(type_array)                                            \
> +static void do_qemu_init_ ## type_array(void)                               \
> +{                                                                           \
> +    type_register_static_array(type_array, ARRAY_SIZE(type_array));         \
> +}                                                                           \
> +type_init(do_qemu_init_ ## type_array)
> +
> +/**
>   * object_class_dynamic_cast_assert:
>   * @klass: The #ObjectClass to attempt to cast.
>   * @typename: The QOM typename of the class to cast to.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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