error type
Go语言中的默认错误对象是error，然而它只能包含一个字符串，如果想让它包含更多的结构化信息，就需要定制一个对象。
Go中的error是一个接口类型。
type error interface {
Error() string
}
fmt包会调用Error() string方法来打印错误。
实现String()方法
package main
import (
"errors"
"fmt"
)
// CusErr is custom error object
type CusErr struct {
Status int
Err error
}
func (cusErr *CusErr) String() string {
return fmt.Sprintf("%s ,%d", cusErr.Err, cusErr.Status)
}
func main() {
cus := &CusErr{10, errors.New("abc error")}
fmt.Println(cus)
cus2 := testErr()
fmt.Println(cus2)
}
// if it returns error object, the built-in error's interface will not be satisfied.
// It needs Error() function.
func testErr() *CusErr {
return &CusErr{1, errors.New("test error")}
}
output
abc error ,10
test error ,1
实现Error()方法，使其符合error接口
package main
import (
"errors"
"fmt"
)
// CusErr is custom error object
type CusErr struct {
Status int
Err error
}
func (cusErr *CusErr) Error() string {
return fmt.Sprintf("msg: %s ,code: %d", cusErr.Err, cusErr.Status)
}
func main() {
cus := &CusErr{10, errors.New("abc error")}
fmt.Println(cus)
cus1 := testErr1()
fmt.Println(cus1)
cus2 := testErr2()
fmt.Println(cus2)
if cuserr, ok := cus2.(*CusErr); ok {
fmt.Println("status:", cuserr.Status)
}
}
func testErr1() *CusErr {
return &CusErr{1, errors.New("test error")}
}
func testErr2() error {
return &CusErr{2, errors.New("test error")}
}
output
msg: abc error ,code: 10
msg: test error ,code: 1
msg: test error ,code: 2
status: 2