Editing Flyweight pattern (section)

=== Caching ===
There are two ways to [[Cache (computing)|cache]] flyweight objects: maintained and unmaintained caches.

Objects with highly variable state can be cached with a [[FIFO (computing and electronics)|FIFO]] structure. This structure maintains unused objects in the cache, with no need to search the cache.

In contrast, unmaintained caches have less upfront overhead: objects for the caches are initialized in bulk at compile time or startup. Once objects populate the cache, the object retrieval algorithm might have more overhead associated than the push/pop operations of a maintained cache.

When retrieving extrinsic objects with immutable state one must simply search the cache for an object with the state one desires. If no such object is found, one with that state must be initialized. When retrieving extrinsic objects with mutable state, the cache must be searched for an unused object to reinitialize if no used object is found. If there is no unused object available, a new object must be instantiated and added to the cache.

Separate caches can be used for each unique subclass of extrinsic object. Multiple caches can be optimized separately, associating a unique search algorithm with each cache. This object caching system can be encapsulated with the [[Chain-of-responsibility pattern|chain of responsibility]] pattern, which promotes loose coupling between components.