Interfaces Quiz

Remember, interfaces are collections of method signatures. A type "implements" an interface if it has all of the methods of the given interface defined on it.

type shape interface {
  area() float64
}

If a type in your code implements an area method, with the same signature (e.g. accepts nothing and returns a float64), then that object is said to implement the shape interface.

type circle struct{
	radius int
}

func (c *circle) area() float64 {
  return 3.14 * c.radius * c.radius
}

This is different from most other languages, where you have to explicitly assign an interface type to an object, like with Java:

class Circle implements Shape