Question

In C#, if a class, such as a manager class, does not have resources, is there any benefit to having it : IDisposable?

Simple example:

public interface IBoxManager
{
 int addBox(Box b);
}

public class BoxManager : IBoxManager
{
 public int addBox(Box b)
 {
  using(dataContext db = new dataContext()){
   db.Boxes.add(b);
   db.SaveChanges();
  }
  return b.id;
 }
}

Will there be any benefit in memory use when using BoxManager if it also implements IDisposable? public class BoxManager : IBoxManager , IDisposable

For example:

BoxManager bm = new BoxManager();
bm.add(myBox);
bm.dispose();//is there benefit to doing this?

Answer 1

There are only 2 reasons for implementing IDisposable on a type

• The type contains native resources which must be freed when the type is no longer used
• The type contains fields of type IDisposable

If neither of these are true then don’t implement IDisposable

EDIT

Several people have mentioned that IDisposable is a nice way to implement begin / end or bookended operations. While that’s not the original intent of IDisposable it does provide for a very nice pattern.

class Operation {
  class Helper : IDisposable {
    internal Operation Operation;
    public void Dispose() {
      Operation.EndOperation();
    }
  }
  public IDisposable BeginOperation() {
    ...
    return new Helper() { Operation = this };
  }
  private void EndOperation() {
    ...
  }
}

Note: Another interesting way to implement this pattern is with lambdas. Instead of giving an IDisposable back to the user and hoping they don’t forget to call Dispose have them give you a lambda in which they can execute the operation and you close out the operation

public void BeginOperation(Action action) {
  BeginOperationCore();
  try {
    action();
  } finally {
    EndOperation();
  }
}