Disposing an IDisposable object stored in a public static field

Question

If a class has an instance field that implements IDisposable then the containing class implements IDisposable and class that fields Dispose method from within its Dispose method.

public class A : IDisposable 
{
    public System.Drawing.Font font = new Font("Arial", 10.0f);

    public void Dispose()
    {
        font.Dispose()
    }
}

(I know I didn't do the dispose pattern correctly, but for sample code should be good enough)

If the field is a static field though where should the call to the field's Dispose be?

public class B
{
    public static System.Drawing.Font font = new Font("Arial", 10.0f);
}

I could make class B implement IDisposable and have that call font.Dispose but if B.font is used again later on that would cause problems. As well as you'd have to remember that dispise accessing a static method you need to create an instance just to call Dispose.

I could also make a static Dispose method but then users have to remember to call Dispose and have to make sure they're the last user of it in the program.

Answer 1

Static fields are initialised when the type is loaded.

Therefore it logically it makes sense to dispose the object assigned to the static field when the containing type is unloaded.

However, types are not unloaded. There may be some exotic complication here around AppDomains, but I suspect that doesn't apply in your case.

Therefore I wouldn't dispose the instance, otherwise you will have a publicly available instance of an object that is unfit for use.