Using Wrapper objects to Properly clean up excel interop objects

Question

All of these questions:

• Excel 2007 Hangs When Closing via .NET
• How to properly clean up Excel interop objects in C#
• How to properly clean up inte

Answer 1

What I'd do:

class ScopedCleanup : IDisposable where T : class
{
    readonly Action cleanup;

    public ScopedCleanup(T o, Action cleanup)
    {
        this.Object = o;
        this.cleanup = cleanup;
    }

    public T Object { get; private set; }

    #region IDisposable Members

    public void Dispose()
    {
        if (Object != null)
        {
            if(cleanup != null)
                cleanup(Object);
            Object = null;
            GC.SuppressFinalize(this);
        }
    }

    #endregion

    ~ScopedCleanup() { Dispose(); }
}

static ScopedCleanup CleanupObject(T o, Action cleanup) where T : class
{
    return new ScopedCleanup(o, cleanup);
}

static ScopedCleanup CleanupComObject(ComType comObject, Action actionBeforeRelease) where ComType : class
{
    return
        CleanupObject(
            comObject,
            o =>
            {
                if(actionBeforeRelease != null)
                    actionBeforeRelease(o);
                Marshal.ReleaseComObject(o);
            }
        );
}

static ScopedCleanup CleanupComObject(ComType comObject) where ComType : class
{
    return CleanupComObject(comObject, null);
}

Usage case. Note the call to Quit, which seems to be necessary to make the process end:

using (var excel = CleanupComObject(new Excel.Application(), o => o.Quit()))
using (var workbooks = CleanupComObject(excel.Object.Workbooks))
    {
        ...
    }