What is Flyweight pattern?
The Flyweight pattern is a structural design pattern that aims to minimize memory usage by sharing common, reusable objects across multiple instances. It is used when you have a large number of similar objects that can be effectively shared to conserve system resources.
In the Flyweight pattern, there are two main components:
- Flyweight: This represents the shared object that can be used in multiple contexts. It contains intrinsic state, which is the shared data that remains constant across different instances. The Flyweight object should be immutable so that it can be safely shared. The Flyweight objects are typically created and managed by a Flyweight Factory.
- Context: This represents the extrinsic state that varies between different instances. It is the information that is specific to a particular context or instance and cannot be shared. The Context is passed to the Flyweight object when it is needed to perform an operation.
The key idea behind the Flyweight pattern is to separate the intrinsic state from the extrinsic state. The intrinsic state is stored in the Flyweight object and can be shared, while the extrinsic state is passed to the Flyweight object when it needs to perform an operation. By sharing the common state across multiple objects, memory consumption is reduced.
Benefits of using the Flyweight pattern include:
- Memory efficiency: The Flyweight pattern helps conserve memory by sharing common state among multiple objects. Instead of each object holding its own copy of the common data, they refer to the shared Flyweight object. This can be particularly useful when dealing with a large number of similar objects, as memory usage is significantly reduced.
- Performance improvement: By sharing the common state, the Flyweight pattern can improve the performance of operations involving the shared state. Since the state is shared, the operations can be performed more efficiently, resulting in faster execution.
- Simplified object creation and management: The Flyweight pattern abstracts the creation and management of shared objects to a Flyweight Factory. This factory ensures that the Flyweight objects are created and reused efficiently, reducing the complexity of managing object creation and ensuring their proper sharing.
- Improved system scalability: With the Flyweight pattern, the system can handle a larger number of objects without exhausting memory resources. By sharing the common state, the system can scale better and accommodate more instances or contexts without significant memory overhead.
However, it’s important to note that the Flyweight pattern introduces a trade-off between memory efficiency and increased complexity due to the need for shared state management. It may not be suitable for all situations, especially when the shared state is small or when the cost of managing shared objects outweighs the memory savings. Careful consideration of the trade-offs is necessary before applying the Flyweight pattern.