Resumable exceptions

[Former Member]

Resume code execution after an exception has been thrown can be very useful in several different scenarios (i.e. processing multiple materials and you want to process all but skip only those where there's an error)

This can be solved quite easily using resumable exceptions

First we define our exception class (can be global - defined in DDIC or locally defined). Nothing special needs to be specified here.

CLASS lcx_my_exception DEFINITION

  INHERITING FROM cx_static_check.

  PUBLIC SECTION.

    DATA:

      message TYPE char50.



    METHODS:

      constructor

        IMPORTING

          message TYPE char50 OPTIONAL.

ENDCLASS.                    "LCX_MY_EXCEPTION DEFINITION



CLASS lcx_my_exception IMPLEMENTATION.

  METHOD constructor.

    super->constructor( ).

    me->message = message.

  ENDMETHOD.                    "CONSTRUCTOR

ENDCLASS.                    "LCX_MY_EXCEPTION IMPLEMENTATION

I will demonstrate both the classic exception and resumable exception on a division operation with methods DIVIDE and DIVIDE_RESUMABLE

CLASS lcl_math IMPLEMENTATION.

  METHOD divide_resumable.

    TRY.

      IF i_denominator = 0.

        RAISE RESUMABLE EXCEPTION TYPE lcx_my_exception

          EXPORTING

            message = 'Divide by zero with the following values:'.

      ELSE.

        result = i_numerator / i_denominator.

      ENDIF.



      WRITE:/ 'Numerator:', i_numerator,

              'Denominator:', i_denominator.

    ENDTRY.

  ENDMETHOD.                    "divide_resumable



  METHOD divide.

    IF i_denominator = 0.

      RAISE EXCEPTION TYPE lcx_my_exception

        EXPORTING

          message = 'Divide by zero with the following values:'.

    ELSE.

      result = i_numerator / i_denominator.

    ENDIF.



* !!! NOT RESUMABLE !!!

* The following line will never be hit when denominator = 0

    WRITE:/ 'Numerator:', i_numerator,

            'Denominator:', i_denominator.

  ENDMETHOD.                    "divide

ENDCLASS.                    "lcl_math IMPLEMENTATION

Note the difference in raising commands:

Method DIVIDE_RESUMABLE

RAISE RESUMABLE EXCEPTION TYPE lcx_my_exception 

Method DIVIDE

RAISE EXCEPTION TYPE lcx_my_exception

Here follows a demo program that calls the division operation in both resumable and non-resumable form:

DATA:

  gr_ex    TYPE REF TO lcx_my_exception,

  g_result TYPE anzh2,

  g_err    TYPE abap_bool.



START-OF-SELECTION.

  TRY.

      g_result = lcl_math=>divide(

        i_numerator = 10

        i_denominator = 0

      ).



*     !!! NOT RESUMABLE !!!

*     The following CASE block will never be executed when denominator = 0

      CASE g_err.

        WHEN space.

          WRITE:/ 'Result:', g_result.

        WHEN OTHERS.

          WRITE:/ 'Result undefined'.

      ENDCASE.



    CATCH lcx_my_exception INTO gr_ex.

      g_err = abap_true.

      WRITE:/ gr_ex->message.

  ENDTRY.



  SKIP 1.

  CLEAR:

    g_err,

    gr_ex.



  TRY.

      g_result = lcl_math=>divide_resumable(

        i_numerator = 10

        i_denominator = 0

      ).



      CASE g_err.

        WHEN space.

          WRITE:/ 'Result:', g_result.

        WHEN OTHERS.

          WRITE:/ 'Result undefined'.

      ENDCASE.



    CATCH BEFORE UNWIND lcx_my_exception INTO gr_ex.

      WRITE:/ gr_ex->message.



      IF gr_ex->is_resumable = abap_true.

        g_err = abap_true.

        RESUME.

      ENDIF.

  ENDTRY.

Note the difference in catch commands:

Method DIVIDE_RESUMABLE (calls RESUME which returns to previous processing right after command which raised this exception)

CATCH BEFORE UNWIND lcx_my_exception INTO gr_ex.

...

RESUME

Method DIVIDE

CATCH lcx_my_exception INTO gr_ex.

And the output of this simple from is shown on follwing screenshot

This article has been taken from my blog at oprsteny.com