A pointer receiver attaches a method to a pointer to a struct value. The declaration `func (g *Game) Play()` lets `Play` operate through the `Game` pointer returned by `New`. section 5.1.1
Use pointer receivers consistently for a type rather than mixing pointer and value receivers. Value receivers are mainly useful for structures that are small in memory; pointer receivers are also required when an operation such as `simplify` needs pointer access. section 5.6 section 6.4.3
Running a game through a pointer receiver
A constructor returns a pointer, and the caller invokes the pointer-receiver method directly:\n\n`func New() *Game {\n g := &Game{}\n return g\n}`\n\n`func (g *Game) Play() {\n fmt.Println("Welcome to Gordle!")\n}`\n\n`g := gordle.New()`\n`g.Play()` section 5.1.1
Listing 5.3 game.go: Using Play to run the game
// Play runs the game.
func (g *Game) Play() {
fmt.Println("Welcome to Gordle!")
fmt.Printf("Enter a guess:\n")
}
Inspect the complete `Play` method declaration and its terminal output. section 5.1.1
Listing 6.30 decimal.go: Implementing the Decimal Stringer
// String implements stringer and returns the Decimal formatted as
// digits and optionally a decimal point followed by digits.
func (d *Decimal) String() string {
// Quick-win, no need to do maths.
if d.precision == 0 {
return fmt.Sprintf("%d", d.subunits) #1
}
centsPerUnit := pow10(d.precision) #2
frac := d.subunits % centsPerUnit
integer := d.subunits / centsPerUnit
decimalFormat := "%d.%0" + #3
strconv.Itoa(int(d.precision)) + "d" #3
return fmt.Sprintf(decimalFormat, integer, frac)
}
Compare a pointer receiver used to implement formatted output for `Decimal`. section 6.4.3
