SAP CLASS ATTRIBUTES documentation, setup help and example usage

ARTICLE

Attributes
Attributes are data objects of any ABAP data type that are internal to a class. The content of the attributes specifies the status of the object. You can also define reference variables, which you can then use to create and address objects. This allows objects to be accessed within classes.
Attributes are defined in the declaration part of a class. Public attributes are completely visible from outside the class and are therefore part of the interface between objects and their users. To encapsulate the status of the object, you need to use protected, package-visible, or private attributes. You can also restrict the changeability of non-private attributes using the
READ-ONLY
addition during the declaration.

Instance Attributes
The content of instance attributes forms the instance-dependent status of the object. Instance attributes are declared using the
DATA statement. You cannot use the
COMMON PART addition in classes.

Static Attributes
The content of static attributes forms the instance-independent status of the object, which is valid for all instances of the class. Static attributes are available once for each class. They are declared using the CLASS-DATA statement and are retained throughout the entire runtime. All the objects within a class can access its static attributes. Changes to a static attribute in an object are visible to all other objects within that class.

Data Types of Attributes
The data types of all attributes, including instance attributes and in particular bound data types , belong to the static properties of a class. Therefore, in a LIKE addition, you can use the class component selector or reference variables to refer to the visible attributes of a class without first creating an object. In this way, you can access the properties of the public static attributes of global classes from every program.

Example
Reference to the data type of an instance attribute attr of a global class cl_global .
DATA dref TYPE REF TO cl_global.

DATA: f1 LIKE cl_global= attr,
f2 LIKE dref- attr.

Boxed Component s
Attributes declared as structures can be declared as static boxes using the BOXED addition, like substructures of nested structures. With static boxes, initial value sharing results in reduced memory requirement for infrequently used structures of regularly used objects. As a boxed component , a static box is a deep component administered using an internal reference, like strings and internal tables.