ABSTRACT
Many programming languages assume the availability of garbage collection. This has led to the development of various means for interacting with the collector in ways that extend the basic semantics of programming language memory management. For example, a program might want to be informed and take some action when a given object is about to be, or has been, reclaimed. We describe such finalisation mechanisms in Section 12.1. Conversely, it is sometimes helpful to support references that do not of themselves force an object to be retained. We consider such weak pointer mechanisms in Section 12.2.
