Methods in Golang

In Go, methods are functions that are associated with a specific type. They allow developers to define behavior for objects of that type. In this article, we will explore the basics of methods in Go, how to define and use them, and the different types of methods available.

Defining Methods in Golang

In Go, methods are defined by associating them with a type using the following syntax −

func (receiver type) methodName(parameters) returnType {
   // method body
}

The "receiver" is the type that the method is associated with. It can be a value or a pointer. The "methodName" is the name of the method. The "parameters" are the input arguments to the method, and the "returnType" is the output type of the method.

Here is an example of a method associated with a type −

type Rectangle struct {
   length float64
   width  float64
}

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

In this example, we define a Rectangle struct and associate an Area() method with it. The method calculates the area of the rectangle using the length and width properties of the struct.

Using Methods in Golang

Methods in Go are called using the dot notation. For example −

r := Rectangle{length: 10.0, width: 5.0}
area := r.Area()

In this example, we create a Rectangle struct with a length of 10.0 and a width of 5.0. We then call the Area() method on the struct to calculate its area.

Types of Methods in Golang

There are two types of methods in Go: value receiver methods and pointer receiver methods.

Value Receiver Methods

Value receiver methods are methods that receive a copy of the value of the receiver. They do not modify the original value of the receiver.

Example

 Here is an example −

package main

import (
   "fmt"
   "math"
)

type Circle struct {
   radius float64
}

func (c Circle) Area() float64 {
   return math.Pi * c.radius * c.radius
}

func main() {
   c := Circle{radius: 5.0}
   fmt.Println("Circle Area:", c.Area())
}

Output

Circle Area: 78.53981633974483

In this example, we define a Circle struct and associate an Area() method with it. The method receives a copy of the Circle struct and calculates its area using the radius property.

Pointer Receiver Methods

Pointer receiver methods are methods that receive a pointer to the value of the receiver. They modify the original value of the receiver.

Example

 Here is an example −

package main

import "fmt"

type Square struct {
   side float64
}

func (s *Square) Scale(factor float64) {
   s.side = s.side * factor
}

func main() {
   sq := Square{side: 5.0}
   fmt.Println("Original Square Side:", sq.side)
   
   sq.Scale(2)
   fmt.Println("Scaled Square Side:", sq.side)
}

Output

Original Square Side: 5
Scaled Square Side: 10

In this example, we define a Square struct and associate a Scale() method with it. The method receives a pointer to the Square struct and scales its side property by the factor passed as an argument.

Conclusion

Methods in Go allow developers to define behavior for objects of a specific type. By associating methods with a type, developers can create more intuitive and expressive code. There are two types of methods in Go: value receiver methods and pointer receiver methods. Value receiver methods receive a copy of the value of the receiver, while pointer receiver methods receive a pointer to the value of the receiver. By using methods in Go, developers can create more efficient and flexible code.