Methods

Context

Go does not have classes, but you can define methods on types. A method is a function with a special receiver argument. The receiver can be a value or a pointer. Methods allow you to associate behavior with custom types.

Example

Define a Rectangle struct and methods to calculate area and perimeter.

Code example

package main

import "fmt"

type Rectangle struct {
    Width, Height float64
}

// Value receiver (does not modify the original)
func (r Rectangle) Area() float64 {
    return r.Width * r.Height
}

// Pointer receiver (can modify the struct)
func (r *Rectangle) Scale(factor float64) {
    r.Width *= factor
    r.Height *= factor
}

func main() {
    rect := Rectangle{Width: 10, Height: 5}
    fmt.Println("Area:", rect.Area())

    rect.Scale(2)
    fmt.Println("After scaling, area:", rect.Area())
}

Output

Area: 50
After scaling, area: 200

Useful links

• Go by Example: Methods
• Go spec: Method declarations