Software Design Patterns Questions Long
The Prototype design pattern is a creational design pattern that allows the creation of objects based on an existing object, known as the prototype. It involves creating a clone of the prototype object and modifying it as required, rather than creating new objects from scratch. This pattern is useful when the creation of objects is costly or complex, and when the objects to be created share a lot of common characteristics.
The Prototype design pattern consists of the following key components:
1. Prototype: This is the interface or abstract class that declares the clone method, which is used to create a copy of the object.
2. Concrete Prototype: This is the concrete implementation of the prototype interface. It implements the clone method to create a copy of itself.
3. Client: This is the class that uses the prototype to create new objects. It requests the prototype to clone itself and then modifies the cloned object as required.
An example of the Prototype design pattern in a software system is a graphic design application that allows users to create and modify shapes. Instead of creating new shape objects from scratch, the application can use the Prototype design pattern to clone existing shape objects and modify them as required.
Let's consider a scenario where the application has predefined shape objects such as circles, rectangles, and triangles. Each shape object has properties like color, size, and position. Rather than creating new shape objects every time a user wants to create a shape, the application can use the Prototype design pattern.
The Prototype interface or abstract class would define the clone method, which all shape objects would implement. Each shape object would have its own concrete implementation of the clone method, which would create a copy of itself.
The client class, which represents the user interface of the application, would have a shape manager that stores the prototype objects. When a user wants to create a shape, the client class would request the shape manager to clone the desired shape object. The cloned object would then be modified based on the user's input, such as changing the color or size.
For example, if a user wants to create a red circle, the client class would request the shape manager to clone the circle prototype object. The cloned circle object would then be modified to have a red color.
By using the Prototype design pattern, the application avoids the overhead of creating new shape objects from scratch and allows for easy modification of existing objects. It promotes code reusability and improves performance by reducing object creation time and memory usage.