Composite Data Types [AX 2012]

The composite data types in X++ are listed in the following table. For more information about each data type,

X++ composite data types	Description
Arrays	An array is a list of items with the same data type and the same name—only the index differs.
Containers	A container is a dynamic list of items containing primitive data types and/or some composite data types.
Classes as Data Types	A class is a type definition that describes both variables and methods for instances (objects) of the class.
Delegates as data types	A delegate collects methods that subscribe to the delegate. The delegate specifies the parameter signature that all its subscriber methods must share. When the delegate is called, the delegate calls each of its subscribers.
Tables as Data Types	All tables defined in the database can be handled as class definitions.

The Collection classes allow you to create arrays, lists, sets, maps, and structs that can hold any data type, including objects.

Default Values on Composite Types

The default values for variables of composite data types are shown in the following table.

Data type	Default	Description
Array	as data type	The default value on an array is that all items have their normal default value.
Container	empty	The default value of a container is empty. The container does not contain any values.
Class	null	A class is only a definition for objects, and all objects are null when they are declared.
Delegate	not applicable	No delegate can have a default value. However, each delegate starts with zero methods subscribed to it.
Table	empty	A table variable can be seen as an instance (an object) of the table (class) definition. For every field in a table variable, the default value is empty.