shapes-using-interfaces

README

shapes-using-interfaces example

Calculating the area and perimeter of circles, rectangles and triangles using functions.

This example is done using,

• shapes-using-functions
• shapes-using-methods
• shapes-using-interfaces (This example)

GitHub Webpage

OVERVIEW

You can see the function and methods are basically the same thing. But when we use interfaces we can give a function the type (struct) and the interface will figure it out.

As we go from,

// Get the shape properties
c1Area := circleArea(c1)
c1Perimeter := circlePerimeter(c1)
r1Area := rectangleArea(r1)
r1Perimeter := rectanglePerimeter(r1)
t1Area := triangleArea(t1)
t1Perimeter := trianglePerimeter(t1)

To a simple form,

// Get the shape properties
c1Area := area(c1)
c1Perimeter := perimeter(c1)
r1Area := area(r1)
r1Perimeter := perimeter(r1)
t1Area := area(t1)
t1Perimeter := perimeter(t1)

We can clearly see the goal is to have an interface that has can have different data (e.g. c1, r1, t1), where you can then use that interface as a argument in a function and do something (e.g. area(), perimeter()).

TWO INTERFACES VS ONE INTERFACE

The first example shapes-using-interfaces1.go uses 2 interfaces,

type areaer interface {
    area() float64
}

type perimeterer interface {
    perimeter() float64
}

The second shapes-using-interfaces2.go uses more traditional 1 interface,

type shapes interface {
    area() float64
    perimeter() float64

The end result is the same.

RUN

go run shapes-using-interfaces1.go
go run shapes-using-interfaces2.go