How to Catch an exception in a using block with .NET 2.0?

Question

I'm trying to leverage the using block more and more these days when I have an object that implements IDisposable but one thing I have not figured out is how to catch an exception as I would in a normal try/catch/finally ... any code samples to point me in the right direction?

Edit: The question was modified after reading through the replies. It was "How to Throw an exception in a using block with .NET 2.0?" but I was actually looking for a way to catch these exceptions inside a using block.

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I'm looking for more detail on rolling my own catching block inside a using block.

Edit: What I wanted to avoid is having to use a try/catch/finally inside my using block like @Blair showed. But maybe this is a non issue...

Edit: @Blair, this is exactly what I was looking for, thanks for the detailed reply!

Answer 1

I don't really understand the question - you throw an exception as you normally would. If MyThing implements IDisposable, then:

using ( MyThing thing = new MyThing() )
{
    ...
    throw new ApplicationException("oops");
}

And thing.Dispose will be called as you leave the block, as the exception's thrown. If you want to combine a try/catch/finally and a using, you can either nest them:

try
{
    ...
    using ( MyThing thing = new MyThing() )
    {
        ...
    }
    ...
}
catch ( Exception e )
{
    ....
}
finally
{
    ....
}    

(Or put the try/catch/finally in the using):

using ( MyThing thing = new MyThing() )
{
    ...
    try
    {
        ...
    }
    catch ( Exception e )
    {
        ....
    }
    finally
    {
        ....
    }    
    ...
} // thing.Dispose is called now

Or you can unroll the using and explicitly call Dispose in the finally block as @Quarrelsome demonstrated, adding any extra exception-handling or -recovery code that you need in the finally (or in the catch).

EDIT: In response to @Toran Billups, if you need to process exceptions aside from ensuring that your Dispose method is called, you'll either have to use a using and try/catch/finally or unroll the using - I don't thinks there's any other way to accomplish what you want.