go2 error handling feedback

go2 error handling feedback.md

Import symbol ! to passthrough errors

! is abbreviation of not nil

For example, to call function Sub in caller

func Sub(...) (T1, T2, error) {...}
  
func caller(...) (T3, error) {
	// call Sub(...)
}

Style 1 (same with go1)

	a, b, err := Sub(...)
	if err != nil {
		// do something
	}

Style 2 (!)

	a, b, ! := Sub(...)
		
	// Equivalent to
	a, b, err := Sub()
	if err != nil {
		return (default value of T3), err
	}

Style 3 (! func)

	a, b, !checkError := Sub(...)
	// Equivalent to
	a, b, err := Sub()
	! = checkError(err)
		
	!checkT1, b, !checkError := Sub(...)
	// Equivalent to
	a, b, err := Sub()
	! = checkError(err)
	! = checkT1(a)

Check funcs:

// prototype
func CheckReturn(r interface{}) error {...}
		
func checkError(err error) error {
	if err != nil {
		return errors.Wrap(err, "additional message")
	}
	return nil
}
		
func checkT1(a T1) error {
	if a.EqualTo(...) {
		return errors.Errorf("....")
	}
	return nil
}
		

For whatever it's worth, I really like this one!