Prototype

Prototype Pattern

Intent

Specify the kinds of objects to create using a prototypical instance, and create new objects by copying this prototype.

Problem

You need to create new objects that are similar to existing objects, and object creation is expensive or complex.

Solution

The Prototype pattern creates new objects by cloning existing objects (prototypes) rather than creating them from scratch.

When to Use

• When the classes to instantiate are specified at runtime
• To avoid building a class hierarchy of factories parallel to product hierarchy
• When instances of a class can have only a few different combinations of state
• When object creation is expensive

C# Implementation

See the Program.cs file for a shape registry demonstrating object cloning with prototypes.

Pros

• Can clone objects without coupling to their concrete classes
• Can get rid of repeated initialization code
• Convenient for producing complex objects

Cons

• Cloning complex objects with circular references might be tricky
• Deep copy vs shallow copy considerations