Go2ErrorTree
Proposal is not clear for case if we have error tree.
Error-tree created in according to repository.
Error-tree help to grouping the errors.
Description of new language element errorhandling:
Go code
errorhandling(et interface(){ Add(error) }){
val1, et = function1()
val2, et = function2(val1)
val3, val4, et = function3()
}
Internal interpretation errorhandling:
{ var errLocal error; val1, errLocal = function1(); et.Add(errLocal) }
{ var errLocal error; val2, errLocal = function2(val1); et.Add(errLocal) }
{ var errLocal error; val3, val4, errLocal = function3(); et.Add(errLocal) }
Let's suppose on example:
func printSum(a, b string) error {
x, err := strconv.Atoi(a)
if err != nil {
return err
}
y, err := strconv.Atoi(b)
if err != nil {
return err
}
fmt.Println("result:", x + y)
return nil
}
Add exist error-tree.
func printSum(a, b string) error {
// create error tree
et := errors.New("check input data")
x, err := strconv.Atoi(a)
if err != nil {
et.Add(err)
}
y, err := strconv.Atoi(b)
if err != nil {
et.Add(err)
}
// is error-tree have errors
if et.IsError() {
return et
}
fmt.Println("result:", x + y)
return nil
}
And writing it as:
func printSum(a, b string) error {
// create error tree
et := errors.New("check input data")
errorhandling(et interface{Add(error)}){ // add type just for clearification
x, et := strconv.Atoi(a)
y, et := strconv.Atoi(b)
}
// is error-tree have errors
if et.IsError() {
return et
}
fmt.Println("result:", x + y)
return nil
}Now, we take next example:
func CopyFile(src, dst string) error {
r, err := os.Open(src)
if err != nil {
return fmt.Errorf("copy %s %s: %v", src, dst, err)
}
defer r.Close()
w, err := os.Create(dst)
if err != nil {
return fmt.Errorf("copy %s %s: %v", src, dst, err)
}
if _, err := io.Copy(w, r); err != nil {
w.Close()
os.Remove(dst)
return fmt.Errorf("copy %s %s: %v", src, dst, err)
}
if err := w.Close(); err != nil {
os.Remove(dst)
return fmt.Errorf("copy %s %s: %v", src, dst, err)
}
return nil
}
Rewrite in according to error-tree approach:
func CopyFile(src, dst string) (err error) {
// create error tree
et := errors.New("CopyFile")
defer func() {
if et.IsError() {
er.Add(fmt.Errorf("copy %s %s", src, dst))
} else {
err = nil
}
}()
r, err := os.Open(src)
if err != nil {
et.Add(err)
return et
}
defer func() {
et.Add(r.Close())
}()
w, err := os.Create(dst)
if err != nil {
et.Add(err)
return et
}
if _, err := io.Copy(w, r); err != nil {
et.Add(err)
et.Add(w.Close())
et.Add(os.Remove(dst))
return et
}
if err := w.Close(); err != nil {
et.Add(err)
et.Add(os.Remove(dst))
return et
}
return nil
}
Rewrite with errorhandling:
func CopyFile(src, dst string) (err error) {
// create error tree
et := errors.New("CopyFile")
defer func() {
if et.IsError() {
er.Add(fmt.Errorf("copy %s %s", src, dst))
} else {
err = nil
}
}()
r, err := os.Open(src)
if err != nil {
et.Add(err)
return et
}
defer func() {
et.Add(r.Close())
}()
w, err := os.Create(dst)
if err != nil {
et.Add(err)
return et
}
if _, err := io.Copy(w, r); err != nil {
errorhandling(et) {
et = err
et = w.Close()
et = os.Remove(dst)
}
return et
}
if err := w.Close(); err != nil {
errorhandling(et) {
et = err
et = os.Remove(dst)
}
return et
}
return nil
}If we have a tree, then we have to add function for moving by tree as go.ast.Walk.
Example of Walking by error-tree taked from git:
type ErrorValue struct {
ValueName string
Reason error
}
func (e ErrorValue) Error() string {
return fmt.Sprintf("Value `%s`: %v", e.ValueName, e.Reason)
}
func Example() {
// some input data
f := math.NaN()
i := -32
var s string
// checking
var et Tree
et.Name = "Check input data"
if math.IsNaN(f) {
et.Add(ErrorValue{
ValueName: "f",
Reason: fmt.Errorf("is NaN"),
})
}
if f < 0 {
et.Add(fmt.Errorf("Parameter `f` is negative"))
}
if i < 0 {
et.Add(fmt.Errorf("Parameter `i` is less zero"))
}
if s == "" {
et.Add(fmt.Errorf("Parameter `s` is empty"))
}
if et.IsError() {
fmt.Println(et.Error())
}
// walk
Walk(&et, func(e error) {
fmt.Fprintf(os.Stdout, "%-25s %v\n", fmt.Sprintf("%T", e), e)
})
// Output:
// Check input data
// ├──Value `f`: is NaN
// ├──Parameter `i` is less zero
// └──Parameter `s` is empty
//
// errors.ErrorValue Value `f`: is NaN
// *errors.errorString Parameter `i` is less zero
// *errors.errorString Parameter `s` is empty
}
React
Typescript
Django
Laravel
Facebook
Microsoft
Google
Alibaba
D3
Tencent