How to do C++ style destructors in C#?

try
{
    PleaseDisposeMe a = new PleaseDisposeMe();
    throw new Exception();
    a.Dispose();
}
catch (Exception ex)
{
    Log(ex);
}

// This next call will throw a time-out exception unless the GC
// runs a.Dispose in time.
PleaseDisposeMe b = new PleaseDisposeMe();

class MyDisposable: IDisposable {
    public void Dispose() {
        lock(this) {
            if (disposed) {
                return;
            }

            disposed = true;
        }

        GC.SuppressFinalize(this);

        // Do actual disposing here ...
    }

    private bool disposed = false;
}

~ClassName()
{
}

public class DisposableFinalisableClass : IDisposable
	{
		~DisposableFinalisableClass()
		{
			Dispose(false);
		}

		public void Dispose()
		{
			Dispose(true);
		}

		protected virtual void Dispose(bool disposing)
		{
			if (disposing)
			{
				// tidy managed resources
			}

			// tidy unmanaged resources
		}
	}

using (SqlConnection con = new SqlConnection("DB con str") )
using (SqlCommand com = new SqlCommand( con, "sql query") )
{
    //now code is indented one level
    //technically we're nested twice
}

PleaseDisposeMe a;
try
{
    a = new PleaseDisposeMe();
    throw new Exception();
}
catch (Exception ex) { Log(ex); }
finally {
    //this always executes, even with the exception
    a.Dispose();
}