type-assert.go

type TestData struct {
	i int
	k int
}

func getIfc(data TestData) interface{} {
	return data
}

func getMyData(b *testing.B, ifc interface{}, expected TestData) TestData {
	data := ifc.(TestData)
	if data.i != expected.i {
		b.Fatalf("%d instead of %d", data.i, data.i)
	}
	if data.k != expected.k {
		b.Fatalf("%d instead of %d", data.k, data.k)
	}
	return ifc.(TestData)
}

func getMyDataFast(ifc interface{}) TestData {
	return ifc.(TestData)
}

func BenchmarkTypeAssert(b *testing.B) {
	for i := 0; i < b.N; i++ {
		for k := 0; k < 1000; k++ {
			data := TestData{i, k}
			myIfc := getIfc(data)
			getMyData(b, myIfc, data)
		}
	}
}

func BenchmarkTypeAssertFast(b *testing.B) {
	for i := 0; i < b.N; i++ {
		for k := 0; k < 1000; k++ {
			data := TestData{i, k}
			myIfc := getIfc(data)
			data = getMyDataFast(myIfc)
			if data.i != i {
				b.Fatalf("%d instead of %d", data.i, i)
			}
			if data.k != k {
				b.Fatalf("%d instead of %d", data.k, k)
			}
		}
	}
}