Исходники и презентации

lessons/errors/optional/main.go

@@ -0,0 +1,42 @@
+package main
+
+import "fmt"
+
+var NullOptional = Optional[int]{}
+
+type Optional[T any] struct {
+	value   T
+	present bool
+}
+
+func NewOptional[T any](value T) Optional[T] {
+	return Optional[T]{
+		value:   value,
+		present: true,
+	}
+}
+
+func (o *Optional[T]) HasValue() bool {
+	return o.present
+}
+
+func (o *Optional[T]) Value() T {
+	return o.value
+}
+
+func divide(lhs, rhs int) Optional[int] {
+	if rhs == 0 {
+		return NullOptional
+	}
+
+	result := lhs / rhs
+	return NewOptional(result)
+}
+
+func main() {
+	x := 100
+	y := 0
+
+	optional := divide(x, y)
+	fmt.Println(optional)
+}