[#140] sdk/object: Define Attribute type

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>

pkg/object/attribute.go

@@ -0,0 +1,45 @@
+package object
+
+import (
+	"github.com/nspcc-dev/neofs-api-go/v2/object"
+)
+
+// Attribute represents v2-compatible object attribute.
+type Attribute object.Attribute
+
+// NewAttributeFromV2 wraps v2 Attribute message to Attribute.
+func NewAttributeFromV2(aV2 *object.Attribute) *Attribute {
+	return (*Attribute)(aV2)
+}
+
+// NewAttribute creates and initializes blank Attribute.
+//
+// Works similar as NewAttributeFromV2(new(Attribute)).
+func NewAttribute() *Attribute {
+	return NewAttributeFromV2(new(object.Attribute))
+}
+
+// GetKey returns key to the object attribute.
+func (a *Attribute) GetKey() string {
+	return (*object.Attribute)(a).GetKey()
+}
+
+// SetKey sets key to the object attribute.
+func (a *Attribute) SetKey(v string) {
+	(*object.Attribute)(a).SetKey(v)
+}
+
+// GetValue return value of the object attribute.
+func (a *Attribute) GetValue() string {
+	return (*object.Attribute)(a).GetValue()
+}
+
+// SetValue sets value of the object attribute.
+func (a *Attribute) SetValue(v string) {
+	(*object.Attribute)(a).SetValue(v)
+}
+
+// ToV2 converts Attribute to v2 Attribute message.
+func (a *Attribute) ToV2() *object.Attribute {
+	return (*object.Attribute)(a)
+}