Persistent Lists

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Persistent lists can be saved to a form file. Because of this, they are often used as the type of a published property on a component. You can add items to the list at design time, and those items are saved with the object so that they are there when the component that uses them is loaded into memory at run time. There are two main types of persistent lists: string lists and collections.

Examples of string lists include TStringList and THashedStringList. String lists, as the name implies, contain strings. They provide special support for strings of the form Name=Value, so that you can look up the value associated with a name. In addition, most string lists let you associate an object with each string in the list. String lists are described in more detail in Working with String Lists.

Collections descend from the class TCollection. Each TCollection descendant is specialized to manage a specific class of items, where that class descends from TCollectionItem. Collections support many of the common list operations. All collections are designed to be the type of a published property, and many can not function independently of the object that uses them to implement on of its properties. At design time, the property whose value is a collection can use the collection editor to let you add, remove, and rearrange items. The collection editor provides a common user interface for manipulating collections.

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