mas ejemplos

gobyexample/errors.go

@@ -0,0 +1,53 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+)
+
+func f1(arg int) (int, error) {
+	if arg == 42 {
+		return -1, errors.New("can't work with 42")
+	}
+	return arg + 3, nil
+}
+
+type argError struct {
+	arg int
+	prob string
+}
+
+func (e *argError) Error() string {
+	return fmt.Sprintf("%d - %s", e.arg, e.prob)
+}
+
+func f2(arg int) (int, error) {
+	if arg == 42 {
+		return -1, &argError{arg,  "can't work with it"}
+	}
+	return arg + 3, nil
+}
+
+func main() {
+	for _, i := range []int{7 ,42} {
+		if r, e := f1(i); e != nil {
+			fmt.Println("f1 failed:", e)
+		} else {
+			fmt.Println("f1 worked:", r)
+		}
+	}
+
+	for _, i := range []int{7, 42} {
+		if r,e := f2(i); e != nil {
+			fmt.Println("f2 failed:", e)
+		} else {
+			fmt.Println("f2 worked:", r)
+		}
+	}
+
+	_, e := f2(42)
+	if ae, ok := e.(*argError); ok {
+		fmt.Println(ae.arg)
+		fmt.Println(ae.prob)
+	}
+}