Mastering Golang: Pointers and Receivers

Structs

In Go, pointers and receivers play a crucial role when working with structures (also known as structs). Understanding how pointers and receivers work with structs is essential for effective Go programming.

Let’s explore how they are used:

Structures (Structs):

A struct is a composite data type that groups together variables with different data types under a single name. Fields within a struct can be of any data type, including other structs.

Here’s an example of a simple struct definition:

type Person struct {
    FirstName string
    LastName  string
    Age       int
}

Pointers to Structs:

In Go, you can create pointers to structs just like you can create pointers to other data types. Pointers are useful when you want to modify the original struct within a function or when you want to avoid copying the entire struct when passing it as an argument.

// Creating a pointer to a struct
personPtr := &Person{"John", "Doe", 30}

// Accessing fields through a pointer
fmt.Println(personPtr.FirstName)

Receivers (Methods):

Receivers are special functions associated with a type, including structs. You can attach methods to a struct by defining a receiver function.

• Value Receivers: A receiver that takes a struct by value creates a copy of the struct. Changes made inside the method do not affect the original struct.

func (p Person) ChangeFirstName(newName string) {
    p.FirstName = newName // This won't modify the original struct
}

Pointer Receivers:

A receiver that takes a pointer to a struct can modify the original struct. It operates on the original instance rather than a copy.

func (p *Person) ChangeLastName(newName string) {
    p.LastName = newName // This will modify the original struct
}

Using Methods:

Once you’ve defined receiver functions, you can call them using an instance of the struct. If the method has a value receiver, it operates on a copy of the struct, while a pointer receiver operates on the original struct.

person := Person{"Alice", "Smith", 25}

// Calling value receiver method (won't modify the original struct)
person.ChangeFirstName("Bob")

// Calling pointer receiver method (will modify the original struct)
personPtr := &person
personPtr.ChangeLastName("Doe")