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);
>
> 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>
