Принцип **відкритості/закритості** (OCP)

The Open/Closed Principle is one of the SOLID principles in programming. It states that a class should be open for extension but closed for modification.

Here’s an explanation with a C# example.

Example: Calculating Area of Shapes (Without OCP)

using System;  
using System.Collections.Generic;  

public class AreaCalculator  
{  
 public double CalculateTotalArea(List<Shape> shapes)  
 {  
 double totalArea = 0;  
 foreach (var shape in shapes)  
 {  
 if (shape is Circle)  
 {  
 totalArea += Math.PI * Math.Pow(((Circle)shape).Radius, 2);  
 }  
 else if (shape is Rectangle)  
 {  
 totalArea += ((Rectangle)shape).Width * ((Rectangle)shape).Height;  
 }  
 }  
 return totalArea;  
 }  
}

public abstract class Shape { }

public class Circle : Shape  
{  
 public double Radius { get; set; }  
}

public class Rectangle : Shape  
{  
 public double Width { get; set; }  
 public double Height { get; set; }  
}

In this example, every time a new shape type is added (for example, Triangle, Square, etc.), the AreaCalculator class must be modified. This violates the Open/Closed Principle because the class is open to modification rather than being closed.

Перекладено з: Open/Closed Principle (OCP)