Document Details

• Created On: May 24, 2024
• Last Updated: May 24, 2024 11:21 PM (GMT+5:30)

Methods

Receiver

• Go doest not support classes. To, define methods that works on a certain type, we use methods [= function + receiver].

  receiver argument is a instance of the type the method works on.

• You can declare methods with pointer receivers. With a value receiver, the Scale method operates on a copy of the original Vertex value. (This is the same behaviour as for any other function argument.) See how Abs method works on a copy of the original Vertex value, while Scale method works on the value to which the receiver points.

• Functions with pointer argument must take a pointer, while methods with pointer receivers take either a value or a pointer as the receiver when they are called.

  Go interprets the statement v.Scale(5) as  (&v).Scale(5) since the Scale method has a pointer receiver.

• Similar thing happens with functions/ methods with value argument.

  In this case, the method call p.Abs() is interpreted as (*p).Abs().

<aside> 💡 In general, all methods on a given type should have either value or pointer receivers, but not a mixture of both.

</aside>

Interfaces

It defines a set of method signatures (names, input parameters, and return types) that a type must implement to satisfy the interface.

type Shape interface {
    Area() float64
    Perimeter() float64
}

This declares a Shape interface with two methods: Area() and Perimeter(). Any type that wants to be considered a "shape" must implement both of these methods.

type Rectangle struct {
    width, height float64
}

func (r Rectangle) Area() float64 {
    return r.width * r.height
}

func (r Rectangle) Perimeter() float64 {
    return 2*r.width + 2*r.height
}
// ... similar implementations for Circle, Triangle, etc.

func PrintShapeInfo(s Shape) {
    fmt.Println("Area:", s.Area())
    fmt.Println("Perimeter:", s.Perimeter())
}

rect := Rectangle{width: 5, height: 10}
PrintShapeInfo(rect)