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As mentioned above, to create a collection, you can derive
it from the IList
interface. Here is an example:
#pragma once
using namespace System::Collections;
public ref class CBookList : public IList
{
};
This System::Collections::IList interface is declared as follows:
public interface class IList : ICollection, IEnumerable
This System::Collections::Generic::IList interface is declared as follows:
generic<typename T>
public interface class IList : ICollection<T>,
IEnumerable<T>,
IEnumerable
This means that the IList interface extends both the ICollection
and the IEnumerable interfaces. This also implies that you must implement
the members of these parent interfaces. In other words, you must implement the
Count property, the SyncRoot property, the IsSynchronized
property, and the CopyTo() method of the ICollection interface.
From what we learned with ICollection, here are examples of implementing these
members for the System::Collections::IList interface:
Header File: BookList.h
#pragma once
using namespace System;
using namespace System::Collections;
public ref class CBookList : public IList
{
private:
int counter;
array<Object ^> ^ objs;
public:
CBookList(void);
virtual property int Count
{
int get() { return counter; }
}
virtual property bool IsSynchronized
{
bool get() { return false; }
}
virtual property Object ^ SyncRoot
{
Object ^ get() { return this; }
}
virtual void CopyTo(Array ^ ary, int index);
};
Source File: BookList.cpp
#include "BookList.h"
CBookList::CBookList(void)
: counter(0),
objs(gcnew array<Object ^>(5))
{
}
void CBookList::CopyTo(Array ^ ary, int index)
{
}
You must also implement the System::Collections::GetEnumerator()
(or the System::Collections::Generic::GetEnumerator()) method of
the System::Collections::IEnumerable (or of the System::Collections::Generic::IEnumerable) interface. If you don't have time to completely implement
it, you can simply return nullptr. Here is an example for the System::Collections::IList
interface:
Header File: BookList.h
#pragma once
using namespace System;
using namespace System::Collections;
public ref class CBookList : public IList
{
private:
int counter;
array<Object ^> ^ objs;
public:
CBookList(void);
virtual property int Count
{
int get() { return counter; }
}
virtual property bool IsSynchronized
{
bool get() { return false; }
}
virtual property Object ^ SyncRoot
{
Object ^ get() { return this; }
}
virtual void CopyTo(Array ^ ary, int index);
virtual IEnumerator ^ GetEnumerator();
};
Source File: BookList.cpp
#include "BookList.h"
CBookList::CBookList(void)
: counter(0),
objs(gcnew array<Object ^>(5))
{
}
void CBookList::CopyTo(Array ^ ary, int index)
{
}
IEnumerator ^ CBookList::GetEnumerator()
{
return nullptr;
}
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 Practical
Learning: Implementing the IList Interface
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- To create a new class, in the Class View, right-click
MusicalInstrumentStore2 -> Add -> Class...
- In the Templates, if necessary, click C++ Class. Click Add
- Set the Name to CStoreItems
- Click Finish
- Change the header file as follows:
#pragma once
using namespace System;
using namespace System::Collections;
[Serializable]
public ref class CStoreItems : public IList
{
private:
int counter;
array<Object ^> ^ items;
public:
CStoreItems(void);
virtual property int Count
{
int get() { return counter; }
}
virtual property bool IsSynchronized
{
bool get() { return false; }
}
virtual property Object ^ SyncRoot
{
Object ^ get() { return this; }
}
virtual void CopyTo(Array ^ arr, int index);
virtual IEnumerator ^ GetEnumerator();
};
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- Change the source file as follows:
#include "StdAfx.h"
#include "StoreItems.h"
CStoreItems::CStoreItems(void)
: counter(0),
items(gcnew array<Object ^>(5))
{
}
void CStoreItems::CopyTo(Array ^ arr, int index)
{
}
IEnumerator ^ CStoreItems::GetEnumerator()
{
return nullptr;
}
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- Save the file
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