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Nim Objects

Objects are created with the "type" statement. For example, the following code creates an object of type "Person":

type Person = object
    name: string
    age: int

Methods

Objects can have methods, which are defined with the "proc" keyword. For example, the following code defines a method called "sayHello" that takes one parameter of type "Person":

proc sayHello(p: Person): string =
    return "Hello, " + p.name

Objects can also inherit from other objects. For example, the following code inherits the "Person" object from the "Animal" object:

type Human = Person of Animal

Inheritance

This means that a "Human" object has all of the properties and methods of a "Person" object, plus any additional properties and methods that are defined in the "Animal" object.

Classes are a way of organizing objects into groups. For example, the following code defines a class called "Mammals" that contains two objects, a "Human" and a "Dog":

class Mammals = object
    Humans: Human
    Dogs: Dog

Classes can also have methods. For example, the following code defines a method called "sayHello" that takes one parameter of type "Mammals":

proc sayHello(m: Mammals): string =
    return "Hello, " + m.Human.name + " and " + m.Dogs.name

In Nim, you can extend a class using the inherits keyword followed by the name of the class you want to inherit from. Here is the basic syntax:

type
  MyBaseClass = object
    # define your base class members here

  MyDerivedClass = object of MyBaseClass
    # define your derived class members here

In this example, we defined a base class MyBaseClass with some members. Then, we created a derived class MyDerivedClass using the of keyword after the class name and then the name of the class we want to inherit from (MyBaseClass).

type
  MyBaseClass = object
    name: string

  MyDerivedClass = object of MyBaseClass
    age: int

proc introduce(self: MyDerivedClass): string =
  result = "My name is " & self.name & " and I am " & $self.age & " years old."

var person = MyDerivedClass(name: "Alice", age: 30)
echo person.introduce()

MyDerivedClass inherits all the members of MyBaseClass, and we can add additional members to it as needed. For instance, here's an extended example:

Read next: Modules