C#

PeterTheSwede wrote:

The only reason that the docs say that you should always allow calls to Dispose even if you are already disposed or not completely initialized is that you may in some cases get called from a catch or finally block that shouldn't have to check whether or not the try block that should have called you actually did it before the exception got thrown. This can never occur simultaneously on different threads, though.

PeterTheSwede wrote:

Note that there is a lot of code (even in the framework) that just crashes spectacularly instead of throwing the proper exceptions if you try to use an object that has been disposed.

MyClass obj = new MyClass();
try
{
    obj.DoSomethingThatCanFail(); // A: we may fail here - obj is not disposed
    obj.Dispose(); // dispose it
    this.DoSomeOtherStuff(); // B: we may fail here - obj could be disposed
}
catch
{
    obj.Dispose(); // make sure obj is disposed
    throw;
}

if (disposed) throw new ObjectDisposedException();

protected virtual void Dispose(bool disposing)
{
    if (!disposed)
    {
        if (disposing)
        {
            // Clean up managed resources here - invoke Dispose() on privately held objects that
            // implement IDisposable, and null out other (expensive) object references so that the
            // GC can reclaim them even if the caller keeps its reference to us:
            // ...
        }
        // Clean up unmanaged (allocated via interop calls etc) resources here:
        // ...
        // If this is a derived class and the base class implements IDisposable as well:
        // base.Dispose(disposing);
        disposed = true;
    }
}

public void Dispose()
{
    Dispose(true);
    GC.SuppressFinalize(this);
}

~MyClass()
{
    Dispose(false);
}