Get Example source ABAP code based on a different SAP table
ARTICLE
Statements in Class and Interface Pools Class pools and interface pools are the ABAP programs in the class library. They are defined using Class Builder tool in ABAP Workbench and are used as a repository for global classes and interfaces.
A program of program type class pool is launched using the statement CLASS-POOL.
A program of program type interface pool is launched using the statement INTERFACE-POOL. These statements are generated by Class Builder. Each class pool or interface pool can only contain a single global class or a single global interface. These classes or interfaces are declared using the following statements:
CLASS ... PUBLIC. ... ENDCLASS.
INTERFACE ... PUBLIC. ... ENDINTERFACE. Class Builder uses the properties entered here to generate these statements.
Further Statements in Class Pools As well as the declaration of the global class, a class pool can only contain the following statements:
Declaration of local data types using the statement TYPES. These data types can be used by the global class in the private visibility section and in the implementation part.
Declaration of local constants using the statement CONSTANTS. These data types can be used by the global class in the private visibility section and in the implementation part.
Declaration of local interfaces using the statements INTERFACE ... ENDINTERFACE. These data types can be used by the global class in the private visibility section and in the implementation part.
Declaration and implementation of local classes using the statements CLASS ... ENDCLASS. These data types can be used by the global class in the private visibility section and in the implementation part.
Definition of macros using DEFINE ...END-OF-DEFINITION. These macros can be used by the global class in the implementation part. Locally defined types, classes, and interfaces in class pools can be used in the following ways:
Only the methods of the global class access the local declarations and implementations in the program. These provide auxiliary methods, for example, which should not be displayed in the interface of the global class. This is the most common scenario. Any changes made to local declarations in the program do not influence the interface of the global class.
As well as the methods in the global class, declarations in the private visibility section of the class also reference local declarations in the program. This is a more unusual scenario, in which changes made to the local declarations influence the interface of the global class, and subclasses and friends of the global class are recompiled before the program is executed again.
Further Statements in Interface Pools In addition to the declaration of the global interface, an interface pool cannot contain any of its own declarations or implementations.
Program Organization Like any other ABAP program, class pools and interface pools consist of a global declaration part for declarations and an implementation part for implementations (or procedures).
This means that the global declaration part of a class pool can contain the declarations of local data types, local interfaces, and local classes, as well as the actual declaration part of the global class. The implementation part of a class pool can contain the implementation parts of local classes, as well as the implementation part of the global class.
The global declaration part of an interface pool can only contain the declaration of type groups and the declaration of the global interface. The implementation part of an interface pool is always empty. The Class Builder organizes the various declarations and implementations ABAP Code Snippet include programs. The developer cannot usually view the names of these programs. A Class Builder function allows you to open the associated include programs in ABAP Editor and edit them. Include programs exist for:
Each visibility section in the declaration part of the global class
Each implementation of a method of the global class
Local declarations and implementations
Test Classes for ABAP Unit To edit the global class, Class Builder provides you with both editing functions for the individual include programs and a source code-based mode in which you can display all the include programs as a single program and edit them.
Restrictions Apart from the statements listed above, statements other than CLASS - ENDCLASS and INTERFACE - ENDINTERFACE are neither required in class pools and interface pools nor are they permitted. The stricter syntax of ABAP Objects applies to all statements permitted. The following restrictions are particularly important:
No processing blocks except methods Neither event blocks such as START-OF-SELECTION, AT SELECTION-SCREEN,GET, or AT LINE-SELECTION nor dialog modules (defined by MODULE - ENDMODULE) are permitted. This means that runtime environment events cannot be processed. ABAP Objects has its own event concept. Neither function modules nor subroutines can be defined using FUNCTION - ENDFUNCTION or FORM - ENDFORM. The methods of a class pool can still call external function modules and subroutines, as well as methods.
No interface work areas to other programs The statements TABLES and NODES and the addition COMMON PART of the DATA statement are not possible. This means that class pools and interface pools do not support any global data areas across programs within a single internal mode.
No dedicated screens Screen processing as implemented in other ABAP programs is not possible. No screens can be defined in a class pool or interface pool. If you want to use classic screens, including selection screens, we recommend that you encapsulate them in function groups . We recommend that you use other suitable output media instead of classic lists. For table list output, use the classes of SAP List Viewer (ALV), such as CL_SALV_TABLE. For simple text output, we recommend browser control wrappers such as dynamic documents or text edit control wrappers.
No processing of extracts Extract data sets cannot be edited in global classes since the defining statement FIELD-GROUPS is not permitted in class or interface pools.
