How do I correctly wrap a Dictionary<T,U> and expose an enumerator?

问题

I am encapsulating a Dictionary in my object. How do I expose IEnumerable>?

Before

class HashRunningTotalDB : Dictionary<int, SummaryEntity>
{
         /... 
} 

// WORKS!
static void Main ()
{
       HashRunningTotalDB  tempDB = new HashRunningTotalDB();
       //todo: load temp DB

       foreach(var item in tempDB)
       {
           Console.Writeline(item.Key + " " + item.Value.SomeProperty);
       }
}

After

class HashRunningTotalDB : IEnumerable
{
    Dictionary<int, SummaryEntity> thisHashRunningTotalDB = new Dictionary<int, SummaryEntity>();

      //QUESTION:  HOW DO I IMPLEMENT THE GENERIC ENUMERATOR HERE?
    // The following doesn't behave the same as the previous implementation
     IEnumerator IEnumerable.GetEnumerator()
    {
        return thisHashRunningTotalDB.GetEnumerator();
    }


    // The following doesn't compile
     Dictionary<int, SummaryEntity>.Enumerator IEnumerable<Dictionary<int, SummaryEntity>>.GetEnumerator()
    {
        return thisHashRunningTotalDB.GetEnumerator();
    }
} 



static void Main ()
{
       HashRunningTotalDB  tempDB = new HashRunningTotalDB();
       //todo: load temp DB


       // NOT WORKING
       foreach(var item in tempDB)
       {
           Console.Writeline(item.Key + " " + item.Value.SomeProperty);
       }
}

回答1:

Implement IEnumerable<KeyValuePair<int, SummaryEntity>>

class HashRunningTotalDB : IEnumerable<KeyValuePair<int, SummaryEntity>>
{
   Dictionary<int, SummaryEntity> thisHashRunningTotalDB =
      new Dictionary<int, SummaryEntity>();

   public IEnumerator<KeyValuePair<int, SummaryEntity>> GetEnumerator()
   {
      return thisHashRunningTotalDB.GetEnumerator();
   }

   IEnumerator IEnumerable.GetEnumerator()
   {
      return GetEnumerator();
   }
}

static void Main()
{
   HashRunningTotalDB tempDB = new HashRunningTotalDB();

   // should work now
   foreach(KeyValuePair<int, SummaryEntity> item in tempDB)
   {
       Console.Writeline(item.Key + " " + item.Value.SomeProperty);
   }
}

来源：https://stackoverflow.com/questions/10712933/how-do-i-correctly-wrap-a-dictionaryt-u-and-expose-an-enumerator