it.unimi.dsi.lang

Interface FlyweightPrototype<T extends FlyweightPrototype<T>>

public interface FlyweightPrototype<T extends FlyweightPrototype<T>>

A prototype providing flyweight copies.

Flyweight copies are useful to implement multithreading on read-only (but maybe stateful) classes. An instance of a class implementing this interface is not necessarily thread safe, but it can be (thread-) safely copied many times (i.e., it can be used as a prototype). All copies will share as much as possible of the class read-only state (so they are flyweight).

In the case an implementation is stateless, it can of course return always the same singleton instance as a copy. At the other extreme, a stateful class may decide to synchronise its methods and return itself as a copy instead. Note that in general the object returned by copy() must replicate the current state of the object, not the object state at creation time. This might require some calls to methods that modify the class internal state: in particular, one should always check whether such methods are pointed out in the documentation of superclasses.

Warning: if copy() accesses mutable internal state, setters and copy() must be suitably synchronised.

Implementing subclasses are invited to use covariant return-type overriding to make copy() return the right type.

Method Summary

Methods

Modifier and Type	Method and Description
T	copy() Returns a copy of this object, sharing state with this object as much as possible.

Method Detail

copy

T copy()

Returns a copy of this object, sharing state with this object as much as possible.