reduce unnecessary allocate in GetOrRegisterGaugeFloat64()

gauge_float64.go

@@ -18,7 +18,7 @@ func GetOrRegisterGaugeFloat64(name string, r Registry) GaugeFloat64 {
 	if nil == r {
 		r = DefaultRegistry
 	}
-	return r.GetOrRegister(name, NewGaugeFloat64()).(GaugeFloat64)
+	return r.GetOrRegister(name, NewGaugeFloat64).(GaugeFloat64)
 }
 
 // NewGaugeFloat64 constructs a new StandardGaugeFloat64.

gauge_float64_test.go

@@ -66,4 +66,7 @@ func TestGetOrRegisterFunctionalGaugeFloat64(t *testing.T) {
 	if g := GetOrRegisterGaugeFloat64("foo", r); 47 != g.Value() {
 		t.Fatal(g)
 	}
+	if g := GetOrRegisterGaugeFloat64("foo.xxx", r); 0.0 != g.Value() {
+		t.Fatal(g)
+	}
 }