object variable is not getting updated in Golang [duplicate] - oop

Question

This question already has answers here:
How to set and get fields in struct's method
(3 answers)
Closed 2 years ago.
I have created a struct Person and a method AddPerson which acts as a constructor for that struct.
package main
import "fmt"
type Person struct {
name string
salary int
balance int
}
func AddPerson(name string, salary int) Person {
p := Person{}
p.name = name
p.salary = salary
p.balance = salary
return p
}
After that I added a method spendMoney which does the following:
func (p Person) spendMoney(amountSpent int) {
p.balance = p.salary - amountSpent
fmt.Println("The amount spent is : ", amountSpent)
fmt.Println("Balance left is : ", p.balance)
}
and a main method shown below:
func main(){
p1 := AddPerson("A", 1500)
p2 := AddPerson("B", 2000)
p1.spendMoney(500)
p2.spendMoney(1000)
fmt.Println(p1.balance) //wanted to check the balance of p1 after spending.
}
I wanted to check the balance of p1 after he has spent the money, but it is still showing the same as before (i.e. 1500). I am new to Golang and come from a Python background, where this way works just fine.

Answer 1

You need to define the method on a pointer to your object, not to the value of your object.
func (p *Person) spendMoney(amountSpent int) {
p.balance = p.salary - amountSpent
}
Contrary to Python, you have to make the distinction between values and pointers. Values are basically copies of variables, modifying them will not make the variable itself change, unless explicitly assigning a new value to that variable.
This tutorial may make you better understand this.