...
If the client needs to detect the error, and you have created a simple error using errors.New, use a var for the error.
Bad | Good |
|---|
| Code Block |
|---|
| // package foo
func Open() error {
return errors.New("could not open")
}
// package bar
if err := foo.Open(); err != nil {
if err.Error() == "could not open" {
// handle
} else {
panic("unknown error")
}
}
|
| | Code Block |
|---|
// package foo
var ErrCouldNotOpen = errors.New("could not open")
func Open() error {
return ErrCouldNotOpen
}
// package bar
if err := foo.Open(); err != nil {
if errors.Is(err, foo.ErrCouldNotOpen) {
// handle
} else {
return errors.Wrap(err, "unknown error")
}
} |
|
...
When adding context to returned errors, keep the context succinct by avoiding phrases like "failed to", which state the obvious and pile up as the error percolates up through the stack:
Bad | Good |
|---|
| Code Block |
|---|
| s, err := store.New()
if err != nil {
return errors.Newf(
"failed to create new store: %s", err)
} |
| | Code Block |
|---|
| s, err := store.New()
if err != nil {
return errors.Wrap(
"new store", err)
} |
|
| Code Block |
|---|
failed to x: failed to y: failed to create new store: the error
|
| | Code Block |
|---|
x: y: new store: the error
|
|
...
