Programming Languages - Struct / Data Class

Simple classes that are used for storing data. It may be called struct, or data class, or case class, or record, depending on the language.

Struct vs tuple: Struct is similar to a tuple , but

• struct needs a name to the data structure and a name for its fields. (struct = named tuple)
• struct has no order of the fields; tuple does.

C++: struct

A struct is the same as a class except that members in structs are default to public, while members in classes default to private.

Go: struct

type Vertex struct {
	X int
	Y int
}

// create
v := Vertex{1, 2}
v2 = Vertex{X: 1}  // Y:0 is implicit
v3 = Vertex{}      // X:0 and Y:0
p  = &Vertex{1, 2} // has type *Vertex

// set
v.X = 4

// get
fmt.Println(v.X)

Rust: struct

struct Employee {
   id: i32,
   name: String,
}

// create
let mut emp1 = Employee {
  id : 10001,
  name : String::from("Joe"),
};

Java: record

Introduced in Java 14.

public record Employee {
  int id,
  String name
} {}

Kotlin: data class

data class Employee(var id: String, var name: String)

// create
val employee = Employee("10001", "Joe")

Constructor, toString(), equals(), hashCode(), and additional copy() and componentN() functions are generated automatically.

Python

namedtuple

namedtuple is immutable

>>> Node = namedtuple('Node', 'val left right')
>>> Node = namedtuple('Node', ['val','left','right'])

>>> Node.__new__.__defaults__ = 0, None, None
>>> Node()
Node(val=0, left=None, right=None)

dataclass

dataclass was added in 3.7

@dataclass decorator and they are supposed to be "mutable namedtuples with default"

Scala

Scala provides case class:

case class Field(
    name: String,
    count: Option[Long]
)