Getters and Setters in Go in Go

type Dog struct {
    age int
}

func NewDog(age int) Dog {
    return Dog{age: age}
}

func (this Dog) getAge() int {
    return this.age
}

func (this *Dog) setAge(value int) {
    if value >= 0 {
        this.age = value
    }
}

Full lesson:

In the Access Modifiers lesson, getName() let other code read an unexported field. Often other code must change a field too. A setter allows that, and it checks each new value first.

The getter

The getter only reads, so a value receiver (this Dog) is enough. Other code calls rex.getAge().

The setter

The setter has a pointer receiver, (this *Dog). Then the change reaches the dog itself, not a copy. Other code calls rex.setAge(4).

The rule

A dog's age can't be negative. So setAge changes this.age only when value is 0 or more. After rex.setAge(-5), the age stays as it was.

Why not an exported field?

With an exported Age field, any code could set it to -5. Nothing would check it. The setter keeps the rule next to the type.

Your task

The Dog struct keeps its age in the unexported field age. Add a getter getAge() that returns it. Add a setter setAge(value) that ignores negative values.

The code in mainFunction creates rex with NewDog(3), then reads and sets its age.

Expected output:

Rex is 3
Rex is still 3
Rex is 4