content

in python, which is a OOP language, we can define a class with its methods:

class rectangle:
	def __init__(self, width, length):
		self.width, self.length = width, length
	def area(self):
		return self.width * self.length
r = rectangle(1, 1)
print(r.area())

go is not a object-oriented language, something similar can be achieved with struct method:

type Rectangle struct {
	width int
	length int
}
func (r Rectangle) area() int {
	return r.width * r.length
} 
main func() {
	rect := Rectangle {1, 1}
	fmt.Println(rect.area())
}

in the function definition of area, (r rectangle) is called a receiver, which is just a param that goes before function name.

in fact, methods are just functions with receiver arguments → A Tour of Go

up

go-struct

down

go-interface-basics-1

reference

A Tour of Go