TCollection Class

TCollection is a container for TCollectionItem objects.

Pascal

TCollection = class(TPersistent);

C++

class TCollection : public TPersistent;

File

Classes

Description

Each TCollection holds a group of TCollectionItem descendants. TCollection maintains an index of the collection items in its Items array. The Count property contains the number of items in the collection. Use the Add and Delete methods to add items to the collection and delete items from the collection.

Objects descended from TCollection can contain objects descended from TCollectionItem. Thus, for each TCollection descendant, there is a corresponding TCollectionItem descendant. The following table lists some typical descendants of TCollection with the corresponding TCollectionItem descendant and the component that uses each pair.

TCollection descendant	TCollectionItem descendant	Component
TAggregates	TAggregate	TClientDataSet
TCookieCollection	TCookie	TWebResponse
TCoolBands	TCoolBand	TCoolBar
TDBGridColumns	TColumn	TDBGrid
TDependencies	TDependency	TService
TDisplayDims	TDisplayDim	TDecisionGrid
TFieldDefs	TFieldDef	TDataSet
THeaderSections	THeaderSection	THeaderControl
TIndexDefs	TIndexDef	TTable
TListColumns	TListColumn	TListView
TParams	TParam	many datasets
TStatusPanels	TStatusPanel	TStatusBar
TWorkAreas	TWorkArea	TListView

The controls that use TCollection and TCollectionItem descendants have a published property that holds a collection. (For example, the Panels property of TStatusBar holds a TStatusPanels.) A standard property editor, referred to generically as the Collection editor, can be invoked from the Object Inspector to edit the items in the collection.

Note: When writing a TCollection descendant that is used by another control, be sure to override the protected GetOwner method of the collection so that it can appear in the Object Inspector.