flyweights

The flyweight pattern is a structural object-oriented design pattern. It is used to support a large number of small objects efficiently. This pattern is particularly useful when dealing with a vast number of similar objects that share common intrinsic properties. The core idea is to divide objects into two parts: intrinsic and extrinsic. Intrinsic state is shared among similar objects and is stored outside the object, while extrinsic state is unique to each object and is passed in as parameters.

By sharing the intrinsic state, the flyweight pattern reduces the memory footprint of the application. Instead of each object storing its own copy of the shared data, multiple objects can refer to a single instance of the intrinsic state. This is achieved by creating a "flyweight factory" that manages and provides access to these shared intrinsic states. When a client requests an object with a specific intrinsic state, the factory either returns an existing flyweight object or creates a new one if it doesn't exist.

The extrinsic state is maintained by the client and passed to the flyweight object when its methods are invoked. This separation allows for a significant reduction in the number of objects, leading to improved performance and reduced memory consumption, especially in applications dealing with large datasets of similar entities. For example, in a text editor, characters can be represented as flyweight objects, where the intrinsic state is the character code itself, and the extrinsic state includes its position and formatting.