Generic Class

C

// No Native Support.
// Use void pointers, macros, or generate type-specific structs/functions.

typedef struct Box
{
	void *value;
} Box;

C++

template <typename T>
class Box
{
public:
	T value;
};

Box<int> box {10};

C#

class Box<T>
{
	public T Value { get; set; }
}

var box = new Box<int> { Value = 10 };

Java

class Box<T> {
	private T value;

	public T getValue() { return value; }
	public void setValue(T value) { this.value = value; }
}

Box<Integer> box = new Box<>();

Rust

struct Boxed<T> {
	value: T,
}

let boxed = Boxed { value: 10 };

Go

// Since Go 1.18
type Box[T any] struct {
	Value T
}

box := Box[int]{Value: 10}

Javascript

// No Native Support.
// Javascript classes are dynamically typed.

class Box {
	constructor(value) {
		this.value = value;
	}
}

Typescript

class Box<T> {
	constructor(public value: T) {}
}

const box = new Box<number>(10);

Python

from typing import Generic, TypeVar

T = TypeVar("T")

class Box(Generic[T]):
	def __init__(self, value: T) -> None:
		self.value = value

box: Box[int] = Box(10)