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From: Rich P on 1 Jul 2010 12:46
I am attempting to create a custom collection class which implements
IDictionary -- with parameters --

public class MyClassCollection : IDictionary <int, MyClass>

The purpose for this effort is to learn C# programmer at a slightly
deeper level. I have a working sample that does not include parameters.
When I add the parameters
<int, MyClass> this is when I get errors.

At this time -- my collection class -- with the parameters -- WILL hold
a collection of custom class objects. Right now -- my collection class
can store my custom class objects, and I can retrieve a count of objects
being store. My problem is iterating through the collection class. I
added a private class for iterating, and that caused 2 errors to pop up.
If I remove the private class - the errors go away. Currently, I don't
have enough background with Interfaces and am having diffuculty
proceeding. Here are the 2 error messages I am getting with what I have
so far, and below that is the code:

Error 1
'InterfaceDictionary.MyClassCollection.MyClassCollectionEnumerator' does
not implement interface member
'System.Collections.IEnumerable.GetEnumerator()'

Error 2
'InterfaceDictionary.MyClassCollection.MyClassCollectionEnumerator' does
not implement interface member
'System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyVa
luePair<int,InterfaceDictionary.MyClass>>.GetEnumerator()'

here is my code -- how can I make this work?
----------------------------------------------------

class Program
{
static void Main(string[] args)
{

MyClass e1, e2;
e1 = new MyClass(1001, "Andy Reid");
e2 = new MyClass(1002, "Kara Lang");

MyClassCollection eData = new MyClassCollection(2);
eData.Add(e1.EmpID, e1);
eData.Add(e2.EmpID, e1);
Console.WriteLine(eData.Count.ToString());

foreach (KeyValuePair<int, MyClass> de in eData)
{
Console.WriteLine(de.Key.ToString() + " " + de.Value.ToString());
}
}
}


public class MyClass
{
public int EmpID;
public string EmpName;

public MyClass(int i, string s)
{
EmpID = i;
EmpName = s;
}
}

public class MyClassCollection : IDictionary <int, MyClass>
{
// The array of items
private DictionaryEntry[] items;
private Int32 ItemsInUse = 0;
private Int32 Idx = 0;

//// Construct the SimpleDictionary with the desired number of
items.
//// The number of items cannot change for the life time of this
SimpleDictionary.
public MyClassCollection(Int32 numItems)
{
items = new DictionaryEntry[numItems];
}

#region IDictionary<int,MyClass> Members

public void Add(int key, MyClass value)
{
if (ItemsInUse == items.Length)
throw new InvalidOperationException("The dictionary cannot hold
any more items.");
items[ItemsInUse++] = new DictionaryEntry(key, value);

//throw new NotImplementedException();
}

public bool ContainsKey(int key)
{
throw new NotImplementedException();
}

public ICollection<int> Keys
{
get { throw new NotImplementedException(); }
}

public bool Remove(int key)
{
throw new NotImplementedException();
}

public bool TryGetValue(int key, out MyClass value)
{
throw new NotImplementedException();
}

private class MyClassCollectionEnumerator :
IEnumerable<KeyValuePair<int,MyClass>>
{
//how/where do I implement the elements listed in the error
messages?

// implementation of constructor, IEnmerator members, etc. here
public MyClassCollectionEnumerator(MyClassCollection mc)
{

}

}


public ICollection<MyClass> Values
{
get { throw new NotImplementedException(); }
}

public MyClass this[int key]
{
get
{
return this[key]; ;
throw new NotImplementedException();
}
set
{
throw new NotImplementedException();
}
}

#endregion

#region ICollection<KeyValuePair<int,MyClass>> Members

public void Add(KeyValuePair<int, MyClass> item)
{
throw new NotImplementedException();
}

public void Clear()
{
throw new NotImplementedException();
}

public bool Contains(KeyValuePair<int, MyClass> item)
{
throw new NotImplementedException();
}

public void CopyTo(KeyValuePair<int, MyClass>[] array, int arrayIndex)
{
throw new NotImplementedException();
}

public int Count
{
get { return ItemsInUse; }
}

public bool IsReadOnly
{
get { throw new NotImplementedException(); }
}

public bool Remove(KeyValuePair<int, MyClass> item)
{
throw new NotImplementedException();
}

#endregion

#region IEnumerable<KeyValuePair<int,MyClass>> Members

public IEnumerator<KeyValuePair<int, MyClass>> GetEnumerator()
{
//how do I return MyClassCollectionEnumerator ?
//return MyClassCollectionEnumerator...;
throw new NotImplementedException();
}

#endregion

#region IEnumerable Members

IEnumerator IEnumerable.GetEnumerator()
{
throw new NotImplementedException();
}

#endregion
}

Thanks


Rich

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From: Rich P on 1 Jul 2010 16:08
Amazing! Thank you for your reply. Working now.

As for why I am even doing this -- it is all a learning process. Over
the years, I have consistenly only been able to learning something "the
hard way". If it doesn't hurt and my head doesn't feel like it is going
to come off my shoulders - I either won't learn the thing or the thing
wasn't worth learning. With this effort alone, I have learned quite a
bit about interfaces. And I HAVE read up on the subject. I kinda know
the difference between an Interface and an Abstract class. I guess what
I am really learning here -- is the IDE and what it can do (VS2008 in my
case).

Thank you again for your help and thanks to all who have offered
suggestions for this effort.

Rich

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