Using syntax to trigger the calling of all objects that implement Dispose method

Question

Is it possible to use using syntax to trigger all objects that implement IDisposable interface call the corresponding Dispose() method?

For example, if the objects of ObjectOne and ObjectTwo exist in the section of interest, can we make it the way so that the Dispose() method of both objects will be called automatically. As the example shown, I knew how to do it for one Class type, but I don't know how to do this kind of trick for more than one Class type. Because the following syntax is not allowed in C#.

// This is not a valid C# statement

using( ObjectOne one = new ObjectOne();
       OjbectTwo two = new ObjectTwo() )
{
   ...  

  // hopefully, the Dispose methods of both **one** and **two** will be called.
}

A concrete example to illustrate how to trigger the auto-calling Dispose method for just one class type.

namespace ConsoleApplication1
{
    class ObjectOne : IDisposable
    {
        public string ObjectName { get; set; }

        public ObjectOne() : this("Empty") { }
        public ObjectOne(string objName) 
        {
            ObjectName = objName;
        }

        public void Dispose()
        {
            Console.WriteLine("ObjectOne.Dispose " + ObjectName);
        }
    }

    class ObjectTwo : IDisposable
    {
        public string ObjectTwoName { get; set; }

        public ObjectTwo() { }
        public ObjectTwo(string objName)
        {
            ObjectTwoName = objName;
        }

        public void Dispose()
        {
            Console.WriteLine("ObjectTwo.Dispose " + ObjectTwoName);
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("before");

            // make sure that the Dispose method of object one1 and one2 is called
            using (ObjectOne one1 = new ObjectOne(),
                             one2 = new ObjectOne()
                   )
            {
                // section of interest
                Console.WriteLine("middle");
            }

            Console.WriteLine("after");
            Console.ReadLine();
        }
    }
}

Thank you.

possible duplicate of Can i have different type of objects in a C# using block ? — Anthony Pegram
– Anthony Pegram, Commented May 6, 2011 at 16:35
@It seems that the only solution is to concatenate using statement. — q0987
– q0987, Commented May 6, 2011 at 16:44

KeithS · Accepted Answer · 2011-05-06 17:05:21Z

4

You can nest using statements:

using( ObjectOne one = new ObjectOne())
   using( OjbectTwo two = new ObjectTwo() )
   {
      ...  

     // hopefully, the Dispose methods of both **one** and **two** will be called.
   }

EDIT: the only other way would be to implement a custom list of IDisposables:

public class DisposableList : List<IDisposable>, IDisposable
{
   //this is all you need if you will ONLY use it in a using statement or explicitly call Dispose;
   //there is a more developed pattern that performs disposal automatically on finalization.
   public void Dispose()
   {
      foreach(var disposable in this)
         disposable.Dispose();
   }
}

...

using(var disposables = new DisposableList{new ObjectOne(), new ObjectTwo()})
{
   //unfortunately, you must now cast the items back to their types 
   //in order to use them as anything but IDisposables.
   var objectOne = (ObjectOne)disposables[0];
   var objectTwo = (ObjectTwo)disposables[1];

   ...
}

edited May 6, 2011 at 17:05

answered May 6, 2011 at 16:35

KeithS

71.9k24 gold badges118 silver badges167 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

q0987 Over a year ago

this is a good solution, but I am looking for a possible alternative solution. My concern is that if I have 10 such objects, I have to embedded the using 10 times.

Ryan Bennett Over a year ago

Unless you want to place all of the objects into a List<IDisposable> and then loop over each and call .Dispose() you won't get around it.

Ryan Bennett · Accepted Answer · 2011-05-06 16:36:12Z

4

using (ObjectOne one1 = new ObjectOne())                       
using (ObjectTwo one2 = new ObjectTwo())                      
{                 
   // !!!section of interest!!!                 
   Console.WriteLine("middle");             
}

This will call dispose on both objects after the code block.

answered May 6, 2011 at 16:36

Ryan Bennett

3,42222 silver badges33 bronze badges

Comments

Community · Accepted Answer · 2017-05-23 12:19:58Z

1

Take a look at the question I asked some time back

Can i have different type of objects in a C# *using* block?

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

The above is how you handle multiple objects of same type. As answered in the above question, you can also handle multiple objects of different types as well.

edited May 23, 2017 at 12:19

CommunityBot

11 silver badge

answered May 6, 2011 at 16:33

Jude Cooray

19.9k21 gold badges85 silver badges128 bronze badges

1 Comment

q0987 Over a year ago

@I have posted this solution in the example. Here my focus is the second part.

Richard Marskell - Drackir · Accepted Answer · 2011-05-06 16:39:56Z

0

According to this:

Multiple objects can be used with a using statement, but they must be declared inside the using statement, as in the following example:

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

Is this what you're looking for?

Edit: After testing your code, I see the problem. You can't do it with multiple types. So what about something like this:

using (ObjectOne one1 = new ObjectOne())
using (ObjectTwo one2 = new ObjectTwo()) {
    // !!!section of interest!!!
    Console.WriteLine("middle");
}

This essentially nests one using in the other.

Note: In my console this outputs:

before
middle
ObjectTwo.Dispose 
ObjectOne.Dispose Empty
after

edited May 6, 2011 at 16:39

answered May 6, 2011 at 16:33

Richard Marskell - Drackir

13.4k3 gold badges37 silver badges55 bronze badges

3 Comments

q0987 Over a year ago

@Please take a look my posted example, I have shown how to do this in the code.

q0987 Over a year ago

as other people mentioned above, I may not have an alternative way to do this except by using embedded "using" statement. Hopefully, in the near future, C#? may introduce a better solution. -- thank you

Richard Marskell - Drackir Over a year ago

@q0987: This is essentially the same as if you were allowed use different types within the using. What would you want more than this?

Collectives™ on Stack Overflow

Using syntax to trigger the calling of all objects that implement Dispose method

4 Answers 4

2 Comments

Comments

1 Comment

3 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

2 Comments

Comments

1 Comment

3 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related