Structs

Go’s structs are typed collections of fields. They’re useful for grouping data together to form records.
Go Lang supports Object Oriented Programming Concepts with structs.
There are no class in Go Lang.
Structs are mutable.

type person struct {
    name string
    age  int
}

This person struct type has name and age fields.

newPerson constructs a new person struct with the given name. You can safely return a pointer to local variable as a local variable will survive the scope of the function.

func newPerson(name string) *person {
    p := person{name: name}
    p.age = 42
    return &p
}

Access struct fields with a dot.

s := person{name: "Sean", age: 50}
fmt.Println(s.name)

If a struct type is only used for a single value, we don’t have to give it a name. The value can have an anonymous struct type. This technique is commonly used for table-driven tests.

dog := struct {
    name   string
    isGood bool
}{
    "Rex",
    true,
}
fmt.Println(dog)

Methods

Go supports methods defined on struct types.

This area method has a receiver type of *rect.

type rect struct {
    width, height int
}

func (r *rect) area() int {
    return r.width * r.height
}

Methods can be defined for either pointer or value receiver types. Here’s an example of a value receiver.

func (r rect) perim() int {
    return 2*r.width + 2*r.height
}

Here we call the 2 methods defined for our struct. Go automatically handles conversion between values and pointers for method calls. You may want to use a pointer receiver type to avoid copying on method calls or to allow the method to mutate the receiving struct.

func main() {
    r := rect{width: 10, height: 5}
    fmt.Println("area: ", r.area())
    fmt.Println("perim:", r.perim())
}

Structs

Methods​

Methods