Merge pull request #13 from Cleverse/feature/utils/default-optional

DefaultOptional Utils

Author: Planxnx

Diff for: utils/utils.go

@@ -28,6 +28,18 @@ func Optional[T any](opt []T) (optional T, ok bool) {
 	return optional, false
 }
 
+// DefaultOptional extract optional parameter from variadic function parameter.
+// If parameter is not provided or zero value of type T, return defaultValue.
+//
+// It's useful to reduce boilerplate code when implementing optional parameter. You won't need to check if parameter is provided or not.
+func DefaultOptional[T comparable](opt []T, defaultValue T) (result T) {
+	val, ok := Optional[T](opt)
+	if ok && val != Empty[T]() {
+		return val
+	}
+	return defaultValue
+}
+
 // ToZero alias of Zero. returns zero value of the type of the given value.
 func ToZero[T any](value T) (result T) {
 	return Zero[T](value)

Diff for: utils/utils_test.go

@@ -91,3 +91,15 @@ func assertEqualAny(t *testing.T, expected, actual interface{}, msgAndArgs ...in
 		return expected == actual
 	}
 }
+
+func TestDefaultOptional(t *testing.T) {
+	f := func(a int, b ...int) int {
+		_b := DefaultOptional(b, 1)
+		return a + _b
+	}
+
+	assertEqual(t, 3, f(2))
+	assertEqual(t, 3, f(2, 0))
+	assertEqual(t, 3, f(2, 1))
+	assertEqual(t, 4, f(2, 2))
+}