Patching

Finalizer

A finalizer is a method that makes Harmony wrap the original and all other patches in a try/catch block. It can receive a thrown exception and even suppress it or return a different one.

It is a very good candidate for code that has to run regardless of what happens. Its counterpart is a Prefix with no side effects (void return type and no ref/out arguments). These are never skipped and thus serve as a way to run code guaranteed at the start of a method.

Finalizers are commonly used to:

• suppress exceptions
• remap exceptions
• make sure your code is always executed

Suppressing any exceptions

static Exception Finalizer()
{
	return null;
}

Observing exceptions

static void Finalizer(Exception __exception)
{
}

Changing and rethrowing exceptions

[Serializable]
public class MyException : Exception
{
    public MyException() { }
    public MyException(string message) : base(message) { }
    public MyException(string message, Exception innerException) : base(message, innerException) { }
    protected MyException(SerializationInfo serializationInfo, StreamingContext streamingContext) => throw new NotImplementedException();
}

static Exception Finalizer(Exception __exception) => new MyException("Oops", __exception);

Beside their handling of exceptions they can receive the same arguments as Postfixes.