Why Do I Need a Pointer Receiver to Remove Elements from a Slice within a Go Struct?

Removing Elements from a Slice within a Struct

In Go, modifying a receiver object within a method requires the usage of a pointer receiver. This is a technique used to pass a reference to the object, rather than a copy, allowing changes made within the method to be reflected in the original object.

Consider the following Guest struct:

type Guest struct {
    id        int
    name      string
    surname   string
    friends   []int
}

To remove an element from the "friends" slice, one might initially write the following code:

func (self Guest) removeFriend(id int) {
    for i, other := range self.friends {
        if other == id {
            self.friends = append(self.friends[:i], self.friends[i+1:]...)
            break
        }
    }
}

However, this code would fail to remove the element as expected because the "removeFriend" method uses a value receiver instead of a pointer receiver. As a result, the changes made to the "friends" slice in the method are not reflected on the original object.

To rectify this issue, the "removeFriend" method should be revised to use a pointer receiver:

func (self *Guest) removeFriend(id int) {
    // Same logic as before
}

By using a pointer receiver, the method now modifies the original object rather than a copy. As a result, the changes made to the "friends" slice within the method are successfully reflected on the original Guest object.

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