what does a using statement without variable do when disposing?

Question

I\'ve always used using with variable and assignment. Now i have like this a class DbProviderConnection:

public class DbProviderConnection : IDisposable
{
           


        

Answer 1

From C# Specification 8.13 using statement defined as

using-statement:
   using (resource-acquisition) embedded-statement

Where resource-acquisition is

resource-acquisition:
    local-variable-declaration
    expression

In first case you have using which acquires resource via local variable declaration. In second case resource is acquired via expression. So, in second case resouce will be result of cnctn.BeginTransaction() call, which is DbTransaction from your DbProviderConnection class. Using statement disposes its resource after usage. So, yes, DbProviderConnection.Transaction.Dispose() will be called.

UPDATE: According to same article, your second using block will be translated to

DbTransaction resource = cnctn.BeginTransaction();
try
{
    //...
    cnctn.Transaction.Commit();
}
finally 
{
   if (resource != null) 
      ((IDisposable)resource).Dispose();
}