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Classes A class specifies the type of a variable. There are three types of classes in WebObjects: Base Classes. The base classes are Object, Number, and String. They represent a single value. That is, a variable of the Number class represents a single number, and a variable of the String class represent a single string. Composite Classes. The composite classes are Array and Dictionary. Composite classes represent a group of related values. For example, a Dictionary class named Guest might represent all information about one guest, and an Array of Guest might represent a list of all guests. Most of the time when you create a new class in WebObjects Builder, you are creating a Dictionary class. When you define a Dictionary class, you must specify its attributes. Enterprise Object Classes. Enterprise object classes are used in applications that access a database. Object, Number, String, and Array are all part of the Foundation Framework. For example, if you click the array checkbox when creating a variable, you are creating an instance of NSMutableArray (mutable meaning you can add or delete values). If you're unfamiliar with the Foundation Framework, see the Foundation Framework Reference. When you create a dictionary, you're also creating an instance of a Foundation class, namely NSMutableDictionary. The attributes you define for the class are keys to the dictionary. Enterprise object classes are created when you add a display group to your application. See "Creating a WODisplayGroup."

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