1.2 The Type Hierarchy

The Type Hierarchy is the set of classes that form the hierarchy used to build objects that contain data. These classes comprise the data model for DODS. They contain simple data types such as integer and floating point values as well as compound types like structure and sequence. Each type is embodied by a C++class, and the classes are arranged in a class hierarchy, with a BaseType defining properties inherited by all the type classes.

This section contains a brief description of the different types, their relation to one another, and how they are used in an application program. For detailed descriptions of the characteristics of each type, including inheritance diagrams, please see the The DODS Toolkit Reference.

The DODS types can be divided into four categories:

• BaseType
• Simple Types

  Byte	Int16	UInt16	Int32	UInt32	Float32	Float64	Str	Url

• Vector Types

  List

  Array

• Compound Types

  Structure

  Sequence

  Grid

Unlike the other classes in the DODS toolkit, the type classes are abstract classes--in order to be used by a program, you must subclass the hierarchy and create concrete classes to instantiate.

• 1.2.1 Common Ancestor: BaseType
• 1.2.2 Simple Types
• 1.2.3 Vector Types: Array, List
• 1.2.4 Compound Types: Structure, Sequence, Function, Grid