Delphi for .NET Developer’s Guide

Creating a Strongly-Typed Dictionary

As with the Collection, it is likely that you might need a strongly-typed Dictionary. In the HashTable example presented in this chapter, the data stored could have been any type descending from System.Object. The following section illustrates how to create a Dictionary that enforces the TStateInfo type.

Descending from DictionaryBase

The System.Collections namespace defines the DictionaryBase class. From this class, you should derive your strongly-typed dictionary classes. Listing 10.7 shows such a class.

Listing 10.7. Strongly-Typed Dictionary

1: unit d4dnDevGuide.StateDictionary; 2: interface 3: 4: uses 5: System.Collections; 6: 7: type 8: 9: // Define a class to store in the dictionary 10: TStateInfo = ...