Short Text

Function Module Wrapper Interface + Abstract Superclass

Functionality

This class is intended to wrap function modules and dynamically read the "classic" exceptions and automatically turn them into class-based exceptions. The idea is that you subclass this main class so that you inherit all the standard functionality and then add in anything extra you need. · There is automatic recognition of whether the function module has filled the SY-MSGID variables while raising the classical exceptions (some do not, due to the doofus problem ). · If there are classical exceptions, both the technical name (e.g. MONSTER_ONLY_ONE_INCH_TALL above) and any text description of the exception from the Transaction SE37 definition are captured automatically. · You avoid the long string of possible exceptions in the calling code. · While debugging, it’s still possible to tell exactly where the exception was raised. · You can replace the call to the function module with a test double during unit tests. · You can use inline declarations when getting the return parameters. · You can change the chaotic SAP naming conventions for function modules to use a more logical name for your wrapper class—and possibly not name the parameters after German abbreviations (unless you’ve just come to love them after all this time). · You have better syntax checking: a function module doesn’t complain when you pass in the wrong variable type, but a method does. · Sometimes you can simplify the interface (signature) for function modules that have half a million parameters, most of which never get used.

Example

METHOD golf_handicap_of_monster.

remove_existing_messages( ).

CALL FUNCTION 'ZMONSTER_GOLF_SCORES'
  EXPORTING
     id_monster_number             = id_monster_number
  IMPORTING
     ed_golf_handicap              = result
   EXCEPTIONS
    monster_only_one_inch_tall    = 1
    monster_has_no_silly_trousers = 2
    OTHERS                         = 3.

IF sy-subrc <> 0.
   TRY.
      throw_exception_on_error_from( 'ZMONSTER_GOLF_SCORES' ).
    CATCH zcx_function_module_error INTO    DATA(function_module_error).
      "Need to raise the excetion here in the calling code in order to get
      "the call stack correct
      RAISE EXCEPTION function_module_error.
  ENDTRY.
ENDIF.

Further information

Please read the blog https://blogs.sap.com/2016/10/29/harlem-function-module-shuffle/