Template Classes to Manage Collections of Objects
This article was contributed by Per Ghosh.
If you are going to create a project in ATL or some other type, then MFC is often
included. The reason for this is often for a few collection classes and CString.
There will be some overhead in an ATL project if MFC is included and the collection classes
is not that hard to rewrite.
I created some templates that I use and it is working fine for me. The classes are
designed to be fast and use very little memory. They store pointers to classes and
not objects except one. If constructors, copy constructors, assignment and other things
are added then the collection class becomes slower. And it is not much harder to work
with the class if it stores pointers to a class instead of the whole object. Sometimes
it is easier because you don't have to add functions needed for the collection class in
object that is managed by it.
Usage Examples
1. How can I create a string class?
CBuffer<char,'0'> bufferText;
bufferText = "This is a text.";
bufferText += " Some more text";
int iPosition = bufferText.Find( "Some" );
2. How can I store some integer values but none of them has the value -1?
CBuffer<int,-1> bufferInt;
3. How can I store some pointers?
CBuffer<void*,NULL> bufferPtr;
4. I want to store some objects (CMyObject) in a array.
int iDummy;
CMyObject* pMyObject;
CArrayPtr<CMyObject> arrayToMyObject;
arrayToMyObject.Add( new CMyObject() );
iDummy = 10;
arrayToMyObject.Add( new CMyObject( iDummy ) );
iDummy = 20;
arrayToMyObject.InsertAt( 1, new CMyObject( iDummy ) );
pMyObject = arrayToMyObject.GetAt( 0 );
iDummy = arrayToMyObject.GetSize(); // gets the value 3
arrayToMyObject.DeleteItems();
5. I want to store CXxx in a hash.
CMapPtr<ULONG,CXxx> mapptrToXxx;
mapptrToXxx.InitHashTable( 21 );
mapptrToXxx.SetAt( 10, new CXxx );
CXxx* pXxx;
if ( mapptrToXxx.Lookup( 10, &pXxx ) == true )
{ ... }
mapptrToXxx.Empty( true );
Download
Download demo project - 16 KB templ_coll_demo.zip
Download source - 3 KB templ_coll_src.zip
Date Posted: March 22, 1999
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