If possible, prefer to call os.Exit or log.Fatal at most once in your
main(). If there are multiple error scenarios that halt program execution,
put that logic under a separate function and return errors from it.
This has the effect of shortening your main() function and putting all key
business logic into a separate, testable function.
| Bad | Good |
|---|---|
package main
func main() {
args := os.Args[1:]
if len(args) != 1 {
log.Fatal("missing file")
}
name := args[0]
f, err := os.Open(name)
if err != nil {
log.Fatal(err)
}
defer f.Close()
// If we call log.Fatal after this line,
// f.Close will not be called.
b, err := io.ReadAll(f)
if err != nil {
log.Fatal(err)
}
// ...
} |
package main
func main() {
if err := run(); err != nil {
log.Fatal(err)
}
}
func run() error {
args := os.Args[1:]
if len(args) != 1 {
return errors.New("missing file")
}
name := args[0]
f, err := os.Open(name)
if err != nil {
return err
}
defer f.Close()
b, err := io.ReadAll(f)
if err != nil {
return err
}
// ...
} |