TF Go Wrapper: Add String() method to Device

This is useful when printing devices.

PiperOrigin-RevId: 225343692

tensorflow/go/session.go

@@ -71,6 +71,15 @@ type Device struct {
 	MemoryLimitBytes int64
 }
 
+// String describes d and implements fmt.Stringer.
+func (d Device) String() string {
+	memStr := "no memory limit"
+	if d.MemoryLimitBytes >= 0 {
+		memStr = fmt.Sprintf("memory limit %d bytes", d.MemoryLimitBytes)
+	}
+	return fmt.Sprintf("(Device: name \"%s\", type %s, %s)", d.Name, d.Type, memStr)
+}
+
 // Return list of devices associated with a Session
 func (s *Session) ListDevices() ([]Device, error) {
 	var devices []Device

tensorflow/go/session_test.go

@@ -299,3 +299,21 @@ func TestListDevices(t *testing.T) {
 		t.Fatalf("no devices detected")
 	}
 }
+
+func TestDeviceString(t *testing.T) {
+	d := Device{Name: "foo", Type: "bar", MemoryLimitBytes: 12345}
+	got := d.String()
+	want := "(Device: name \"foo\", type bar, memory limit 12345 bytes)"
+	if got != want {
+		t.Errorf("Got \"%s\", want \"%s\"", got, want)
+	}
+}
+
+func TestDeviceStringNoMemoryLimit(t *testing.T) {
+	d := Device{Name: "foo", Type: "bar", MemoryLimitBytes: -1}
+	got := d.String()
+	want := "(Device: name \"foo\", type bar, no memory limit)"
+	if got != want {
+		t.Errorf("Got \"%s\", want \"%s\"", got, want)
+	}
+}