add FromBytes constructor

uuid.go

@@ -97,6 +97,13 @@ func ParseBytes(b []byte) (UUID, error) {
 	return uuid, nil
 }
 
+// FromBytes creates a new UUID from a byte slice. Returns an error if the slice
+// does not have a length of 16. The bytes are copied from the slice.
+func FromBytes(b []byte) (uuid UUID, err error) {
+	err = uuid.UnmarshalBinary(b)
+	return uuid, err
+}
+
 // Must returns uuid if err is nil and panics otherwise.
 func Must(uuid UUID, err error) UUID {
 	if err != nil {

uuid_test.go

@@ -121,6 +121,25 @@ func TestUUID(t *testing.T) {
 	}
 }
 
+func TestFromBytes(t *testing.T) {
+	b := []byte{
+		0x7d, 0x44, 0x48, 0x40,
+		0x9d, 0xc0,
+		0x11, 0xd1,
+		0xb2, 0x45,
+		0x5f, 0xfd, 0xce, 0x74, 0xfa, 0xd2,
+	}
+	uuid, err := FromBytes(b)
+	if err != nil {
+		t.Fatalf("%s", err)
+	}
+	for i := 0; i < len(uuid); i++ {
+		if b[i] != uuid[i] {
+			t.Fatalf("FromBytes() got %v expected %v\b", uuid[:], b)
+		}
+	}
+}
+
 func TestConstants(t *testing.T) {
 	for x, tt := range constants {
 		v, ok := tt.c.(fmt.Stringer)