Question

I have a a list of disposable items that I am adding to collection that already contains a number of disposable items. I wrap the code in a try…finally block so that if an exception is thrown while I am copying the items from the list to the collection all the objects in the list get disposed of correctly:

private static void LoadMenuItems(ApplicationMenu parent)
{
    List<ApplicationMenuItem> items = null;
    try
    {
        items = DataContext.GetMenuItems(parent.Id);
        foreach (var item in items)
        {
            parent.Items.Add(item);
        }
        items = null;
    }
    finally
    {
        if (items != null)
        {
            foreach (var item in items)
            {
                item.Dispose();
            }
        }
    }
}

If an exception occurs after adding a number of the objects to the collection, I’ll have a situation where the collection contains some disposed objects. Which could give rise to those disposed objects being disposed of again in the following try…catch block:

try
{
    // Assume that menu.Items contains some items prior
    // to the call to LoadMenuItems.
    LoadMenuItems(menu);
}
catch
{
    // The Dispose() iterates through menu.Items calling 
    // Dispose() on each.
    menu.Dispose();
}

So what I am looking for possible solutions to stop Dispose() being called twice. I have a solution in mind, but thought I would give it to the community to see if there are any alternatives.

Answer 1

Which could give rise to those disposed objects being disposed of again

Which should be quite alright. The contract for Dispose() is very specific: it should be safe to call it multiple times.

---

But another way to get rid of it:

Analyzing your logic I would say the finally part is superfluous, maybe the analyzer thinks so too. You really do solve the same problem twice.