This pattern is sometimes called an intrusive data structure. For example, see boost::intrusive in the C++ world. It saves allocation, gives better locality, an

This pattern is sometimes called an intrusive data structure. For example, see boost::intrusive in the C++ world. It saves allocation, gives better locality, and allows various optimizations such as the ability to remove an object from a doubly-linked list in constant time. Another way to think about all the offsetof() stuff is that it's emulating multiple inheritance in C. You can think of structures as inheriting the "trait" of being a participant in a container; the "pointer-arithmetic-and-cast" idiom to move from a container entry to the corresponding object is isomorphic to downcasting from the trait to the object that contains it. Interestingly it is not possible to express this pattern in a generic way within Java's type system.