return the variable used for using inside the using C#

Question

I am returning the variable I am creating in a using statement inside the using statement (sounds funny):

public DataTable foo ()
{
    using (DataTable properties = new DataTable())
    {
       // do something
       return properties;
    }
}

Will this Dispose the properties variable??

After doing this am still getting this Warning:

Warning 34 CA2000 : Microsoft.Reliability : In method 'test.test', call System.IDisposable.Dispose on object 'properties' before all references to it are out of scope.

Any Ideas?

Thanks

Answer 1

If you want to return it, you can't wrap it in a using statement, because once you leave the braces, it goes out of scope and gets disposed.

You will have to instantiate it like this:

public DataTable Foo() 
{ 
    DataTable properties = new DataTable();
    return properties; 
} 

and call Dispose() on it later.

Answer 2

Yes, it will dispose it - and then return it. This is almost always a bad thing to do.

In fact for DataTable, Dispose almost never does anything (the exception being if it's remoted somewhere, IIRC) but it's still a generally bad idea. Normally you should regard disposed objects as being unusable.