C# use IDisposable or SafeHandle?

Question

I have read a lot about finalizer and IDisposable in C#. As I finally become clear from this monstrous confusion over finalizer and IDisposable, suddenly, out of nowhere, there is this SafeHandle thing. My belief is completely shaken again. What am I supposed to use?

Answer 1

SafeHandle is only useful when dealing with Win32 Interop calls. In Win32, most things are represented by "handles". This includes Windows, Mutexes, etc. So the .NET SafeHandle uses the disposable pattern to ensure the Win32 handle is properly closed.

So if you are using Win32 Interop calls and getting back Win32 handles, then use SafeHandle. For your own objects, you would stick with IDisposable and a finalizer.

Answer 2

You can/should use SafeHandle for any unamanaged resource which can be represented as IntPtr, i.e. Win32 handles, memory allocated by unmanaged code and so on. When SafeHandle isn't suitable, but you still need to handle unmanaged reources, consider making your own SafeHandle-like class inheriting from CriticalFinalizerObject.

In all other cases (i.e. handling managed resources) implement IDisposable. In most cases you won't need finalizer, most managed resources will be unavailable when finalizer is called, so there would be nothing to do there.