They are much less necessary because garbage collection automates memory management, and much less used because they are not generally executed deterministically – they may not be called in a timely manner, or even at all, and the execution environment cannot be predicted – and thus any cleanup that must be done in a deterministic way must instead be done by some other method, most frequently manually via the dispose pattern. Notably, both Java and Python do not guarantee that finalizers will ever be called, and thus they cannot be relied on for cleanup. Due to the lack of programmer control over their execution, it is usually recommended to avoid finalizers for any but the most trivial operations. In particular, operations often performed in destructors are not usually appropriate for finalizers. A common anti-pattern is to write finalizers as if they were destructors, which is both unnecessary and ineffectual, due to differences between finalizers and destructors. This is particularly common among C++ programmers, as destructors are heavily used in idiomatic C++, following the Resource Acquisition Is Initialization (RAII) idiom. Syntax Programming languages that use finalizers include C++/CLI, C#, Clean, Go, Java, JavaScript and Python. Syntax varies significantly by language. In Java, a finalizer is a method called finalize, which overrides the Object.finalize method. In JavaScript, FinalizationRegistry allows you to request a callback when an object is garbage-collected. In Python, a finalizer is a method called __del__. In Perl, a finalizer is a method called DESTROY. In C#, a finalizer (called "destructor" in earlier versions of the standard) is a method whose name is the class name with ~ prefixed, as in ~Foo – this is the same syntax as a C++ destructor, and these methods were originally called "destructors", by analogy with C++, despite having different behavior, but were renamed to "finalizers" due to the confusion this caused. In C++/CLI, which has both destructors and finalizers, a destructor is a method whose name is the class name with ~ prefixed, as in ~Foo (as in C#), and a finalizer is a method whose name is the class name with ! prefixed, as in !Foo. In Go finalizers are applied to a single pointer by calling the runtime.SetFinalizer function in the standard library. Implementation A finalizer is called when an object is garbage collected – after an object has become garbage (unreachable), but before its memory is deallocated. Finalization occurs non-deterministically,