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Generic and Complete Typing

The example shows how to access generically and completely typed formal parameters.

Other versions: 7.31 | 7.40 | 7.54

Source Code

REPORT demo_typing.

CLASS demo_typing DEFINITION.
  PUBLIC SECTION.
    CLASS-METHODS start.
  PRIVATE SECTION.
    TYPES: BEGIN OF struc1,
             cola TYPE i,
             colb TYPE i,
           END OF struc1,
           BEGIN OF struc2,
             colb TYPE i,
             cola TYPE i,
           END OF struc2,
           itab1g TYPE TABLE OF struc1,
           itab2g TYPE TABLE OF struc2,
           itab2c TYPE TABLE OF struc2 WITH NON-UNIQUE DEFAULT KEY.
    CLASS-METHODS sort_itab IMPORTING VALUE(pg) TYPE itab2g
                                     VALUE(pc) TYPE itab2c.
ENDCLASS.

CLASS demo_typing IMPLEMENTATION.
  METHOD start.
    DATA: tab TYPE itab1g,
          wa  LIKE LINE OF tab.
    tab = VALUE #(
      FOR j = 1 UNTIL j > 5
        ( cola = j colb = 6 - j ) ).
    sort_itab( pg = tab
               pc = tab ).
  ENDMETHOD.
  METHOD sort_itab.
    DATA(out) = cl_demo_output=>new( ).
    SORT pg BY cola.
    out->write_data( pg ).
    SORT pg BY ('COLA').
    out->write_data( pg ).
    SORT pc BY cola.
    out->write_data( pc ).
    SORT pc BY ('COLA').
    out->write_data( pc ).
    out->display( ).
  ENDMETHOD.
ENDCLASS.

START-OF-SELECTION.
  demo_typing=>start( ).

Description

In the class demo_typing, three table types are declared:

  • itab1g has the line type struc1 with the components cola and colb. It is generic since the primary table key has not been specified.
  • itab2g has the line type struc2 with the components colb and cola. It is generic since the primary table key has not been specified.
  • itab2c has the line type struc2 with the components cola and colb. It is complete since the primary table key has been specified.

The method sort_itab has two formal parameters:

  • pg is typed generically with itab2g.
  • pc is typed completely with itab2c.

In the method start, an internal table tab is declared by referring to itab1g. The key is specified implicitly. This table is filled and passed to the formal parameters of sort_itab.

In sort_itab, both formal parameters are sorted twice. In the first sort, the column cola is specified statically as a sort criterion, in the second sort, it is specified dynamically. The behaviour is as follows:

  • The first SORT statement statically accesses the generically typed formal parameter pg. In this case, the typing with itab2g takes priority in which cola is the second column.
  • The second SORT statement dynamically accesses the generically typed formal parameter pg. In this case, the type of the actual parameter itab1g takes priority in which cola is the first colulmn.
  • The third and fourth SORT statements dynamically or statically access the completely typed formal parameter pc. In these cases, the typing with itab2c takes priority in which cola is the second column.

If components of generically typed formal parameters are accessed dynamically, a runtime error may occur if the components do not exist in the actual parameter.