On 17/04/2015 16:56, Paolo Bonzini wrote:
>
>
> On 17/04/2015 16:22, Daniel P. Berrange wrote:
>> A QOM property can be parsed as enum using the visit_type_enum()
>> helper method, but this forces callers to use the more complex
>> generic object_property_add() method when registering it. It
>> also requires that users of that object have access to the
>> string map when they want to read the property value.
>>
>> This patch introduces a specialized object_property_add_enum()
>> method which simplifies the use of enum properties, so the
>> setters/getters directly get passed the int value.
>>
>> typedef enum {
>> MYDEV_TYPE_FROG,
>> MYDEV_TYPE_ALLIGATOR,
>> MYDEV_TYPE_PLATYPUS,
>>
>> MYDEV_TYPE_LAST
>> } MyDevType;
>>
>> Then provide a table of enum <-> string mappings
>>
>> static const char *const mydevtypemap[MYDEV_TYPE_LAST + 1] = {
>> [MYDEV_TYPE_FROG] = "frog",
>> [MYDEV_TYPE_ALLIGATOR] = "alligator",
>> [MYDEV_TYPE_PLATYPUS] = "platypus",
>> [MYDEV_TYPE_LAST] = NULL,
>> };
>>
>> Assuming an object struct of
>>
>> typedef struct {
>> Object parent;
>> MyDevType devtype;
>> ...other fields...
>> } MyDev;
>>
>> The property can then be registered as follows:
>>
>> static int mydev_prop_get_devtype(Object *obj,
>> Error **errp G_GNUC_UNUSED)
>> {
>> MyDev *dev = MYDEV(obj);
>>
>> return dev->devtype;
>> }
>>
>> static void mydev_prop_set_devtype(Object *obj,
>> int value,
>> Error **errp G_GNUC_UNUSED)
>> {
>> MyDev *dev = MYDEV(obj);
>>
>> dev->endpoint = value;
>> }
>>
>> object_property_add_enum(obj, "devtype",
>> mydevtypemap,
>> mydev_prop_get_devtype,
>> mydev_prop_set_devtype,
>> NULL);
On second thought (after seeing patch 7), please add a property type
argument here. We lose introspection of enum property types otherwise.
It's possible to use macros so that 'MyEnum' gets translated to two
arguments '"MyEnum", MyEnum_lookup', but I don't think that's worth the
obfuscation.
Paolo
>> Note there is no need to check the range of 'value' in
>> the setter, because the string->enum conversion code will
>> have already done that and reported an error as required.
>>
>> Signed-off-by: Daniel P. Berrange <berra...@redhat.com>
>> ---
>> include/qom/object.h | 17 ++++++++++++++++
>> qom/object.c | 57
>> ++++++++++++++++++++++++++++++++++++++++++++++++++++
>> 2 files changed, 74 insertions(+)
>>
>> diff --git a/include/qom/object.h b/include/qom/object.h
>> index dfdba2f..3462821 100644
>> --- a/include/qom/object.h
>> +++ b/include/qom/object.h
>> @@ -1262,6 +1262,23 @@ void object_property_add_bool(Object *obj, const char
>> *name,
>> Error **errp);
>>
>> /**
>> + * object_property_add_enum:
>> + * @obj: the object to add a property to
>> + * @name: the name of the property
>> + * @get: the getter or NULL if the property is write-only.
>> + * @set: the setter or NULL if the property is read-only
>> + * @errp: if an error occurs, a pointer to an area to store the error
>> + *
>> + * Add a enum property using getters/setters. This function will add a
>> + * property of type 'enum'.
>> + */
>> +void object_property_add_enum(Object *obj, const char *name,
>> + const char * const *strings,
>> + int (*get)(Object *, Error **),
>> + void (*set)(Object *, int, Error **),
>> + Error **errp);
>> +
>> +/**
>> * object_property_add_tm:
>> * @obj: the object to add a property to
>> * @name: the name of the property
>> diff --git a/qom/object.c b/qom/object.c
>> index 2534398..543cc57 100644
>> --- a/qom/object.c
>> +++ b/qom/object.c
>> @@ -1607,6 +1607,63 @@ void object_property_add_bool(Object *obj, const char
>> *name,
>> }
>> }
>>
>> +typedef struct EnumProperty {
>> + const char * const *strings;
>> + int (*get)(Object *, Error **);
>> + void (*set)(Object *, int, Error **);
>> +} EnumProperty;
>> +
>> +static void property_get_enum(Object *obj, Visitor *v, void *opaque,
>> + const char *name, Error **errp)
>> +{
>> + EnumProperty *prop = opaque;
>> + int value;
>> +
>> + value = prop->get(obj, errp);
>> + visit_type_enum(v, &value, prop->strings, NULL, name, errp);
>> +}
>> +
>> +static void property_set_enum(Object *obj, Visitor *v, void *opaque,
>> + const char *name, Error **errp)
>> +{
>> + EnumProperty *prop = opaque;
>> + int value;
>> +
>> + visit_type_enum(v, &value, prop->strings, NULL, name, errp);
>> + prop->set(obj, value, errp);
>> +}
>> +
>> +static void property_release_enum(Object *obj, const char *name,
>> + void *opaque)
>> +{
>> + EnumProperty *prop = opaque;
>> + g_free(prop);
>> +}
>> +
>> +void object_property_add_enum(Object *obj, const char *name,
>> + const char * const *strings,
>> + int (*get)(Object *, Error **),
>> + void (*set)(Object *, int, Error **),
>> + Error **errp)
>> +{
>> + Error *local_err = NULL;
>> + EnumProperty *prop = g_malloc0(sizeof(*prop));
>> +
>> + prop->strings = strings;
>> + prop->get = get;
>> + prop->set = set;
>> +
>> + object_property_add(obj, name, "enum",
>> + get ? property_get_enum : NULL,
>> + set ? property_set_enum : NULL,
>> + property_release_enum,
>> + prop, &local_err);
>> + if (local_err) {
>> + error_propagate(errp, local_err);
>> + g_free(prop);
>> + }
>> +}
>> +
>> typedef struct TMProperty {
>> void (*get)(Object *, struct tm *, Error **);
>> } TMProperty;
>>
>
> Reviewed-by: Paolo Bonzini <pbonz...@redhat.com>
>
>
