Contnrs

Use TCustomBucketList as a base class for lists of items that fit into a limited number of categories (or buckets). Each bucket can contain multiple items, and there is a well-defined function (the protected BucketFor method) that determines the bucket into which an item belongs. TCustomBucketList descendants can include lists of items that fall into natural categories, or implementations of a hash table.  

Do not create instances of TCustomBucketList. In TCustomBucketList, the BucketFor method is abstract (pure virtual), meaning that descendant classes must override it and provide an implementation.