I have an object that contains a file stream. The file stream is to be open for the lifetime of the object. I want the file stream to close when the object has no more references, but never before then. If Dispose() is called on the object, the file is disposed, but the object may still have references. Calling other methods after that point would not be safe because the file would be disposed already, so I would need to implement checking at the beginning of each method to ensure that the file is still valid (waste of run time).
It might seem like making Dispose() private would solve this issue, but then again, I'm understanding that the destructor might not be called immediately when the object has no more references - so basically I MUST expose a Dispose() method for the caller to do their own cleanup. Doesn't this defeat the purpose of "smart" memory management, and is there any way around this?
If there are no more references to your object, it will be garbage collected together with the inner file stream. During the GC, the file stream's finalizer will be executed and the file will be closed. You don't need Dispose() to achieve it. The problem is that you don't know when the GC will run. It seems your object has a long lifetime, so it will probably be in generation 2. It might take a long time for gen 2 GC to run.
You should implement IDisposable and check the state of your object before every call. If the object was disposed, throw ObjectDisposedException.