Go: Constructors

Go doesn’t have explicit constructors. The idiomatic way to set up new data structures is to use proper zero values coupled with factory functions.

Zero value

Try to make the default zero value useful and document its behavior. Sometimes this is all that’s needed:

// A StopWatch is a simple clock utility.
// Its zero value is an idle clock with 0 total time.
type StopWatch struct {
	start   time.Time
	total   time.Duration
	running bool
  • StopWatch takes advantage of the useful zero values of time.Time, time.Duration and bool.
  • In turn, users of StopWatch can benefit from its useful zero value.
var clock StopWatch // Ready to use, no initialization needed.


If the zero value doesn’t suffice, use factory functions named NewFoo or just New:

scanner := bufio.NewScanner(os.Stdin)
err := errors.New("Houston, we have a problem")


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