c# - Can "using" with more than one resource cause a resource leak?

Question

C# lets me do the following (example from MSDN):

using (Font font3 = new Font("Arial", 10.0f),
            font4 = new Font("Arial", 10.0f))
{
    // Use font3 and font4.
}

What happens if font4 = new Font throws? From what I understand font3 will leak resources and won't be disposed of.

• Is this true? (font4 won't be disposed of)
• Does this mean using(... , ...) should be avoided altogether in favor of nested using?

Answer 1

No.

The compiler will generate a separate finally block for each variable.

The spec (§8.13) says:

When a resource-acquisition takes the form of a local-variable-declaration, it is possible to acquire multiple resources of a given type. A using statement of the form

using (ResourceType r1 = e1, r2 = e2, ..., rN = eN) statement 

is precisely equivalent to a sequence of nested using statements:

using (ResourceType r1 = e1)
   using (ResourceType r2 = e2)
      ...
         using (ResourceType rN = eN)
            statement