topic Why can't we pass data ref variable of type string to perform with USING import par TYPE REF TO data in Application Development and Automation Discussions

Why can't we pass data ref variable of type string to perform with USING import par TYPE REF TO data

rajivsap — Mon, 29 Mar 2021 23:58:04 GMT

Why can't we pass data ref variable of static_type string to perform w/h USING import_par TYPE REF TO data?

REPORT ZABAP_OBJECTS_STRING_VAR_REF.

DATA: lr_string TYPE REF TO string.

CREATE DATA lr_string.
lr_string->* = 'String'.

PERFORM pass_string_as_im USING lr_string.

FORM pass_string_as_im USING
*** im_string TYPE REF TO data. " Syntax_Error-1
im_string TYPE REF TO string. "Working
BREAK-POINT.
ENDFORM .

"Syntax_Error-1-In PERFORM or CALL FUNCTION "PASS_STRING_AS_IM", the actual parameter "LR_STRING" is incompatible with the formal parameter "IM_STRING".

Re: Why can't we pass data ref variable of type string to perform with USING import par TYPE REF TO data

matt — Tue, 30 Mar 2021 06:39:55 GMT

Don't use FORM and PERFORM. They're obsolete. Use classes and methods instead. It works fine there.

CLASS lcl_main DEFINITION.
  PUBLIC SECTION.
    METHODS set
      IMPORTING i_thing TYPE REF TO data.
ENDCLASS.

CLASS lcl_main IMPLEMENTATION.
  METHOD set.
  ENDMETHOD.
ENDCLASS.

START-OF-SELECTION.
  DATA main TYPE REF TO lcl_main.
  CREATE OBJECT main.
  DATA string TYPE REF TO string.
  main->set( string ).

It is a bit odd that FORM doesn't allow it.

Re: Why can't we pass data ref variable of type string to perform with USING import par TYPE REF TO data

Sandra_Rossi — Tue, 30 Mar 2021 07:00:21 GMT

I guess the issue is more about USING which works like CHANGING. Even in methods, CHANGING doesn't allow a upcast/downcast in type. Here it's about a data reference, but I guess it's the same bizarre thing as with object references: https://blogs.sap.com/2011/10/05/abap-trapdoors-type-lock-in/

Re: Why can't we pass data ref variable of type string to perform with USING import par TYPE REF TO data

touzik_itc — Tue, 30 Mar 2021 08:30:05 GMT

In this form it work for subroutines too:

DATA: lr_string TYPE REF TO data.
lr_string = REF #( 'String' ).

PERFORM pass_string_as_im USING lr_string.

FORM pass_string_as_im USING
im_string TYPE REF TO data. " no syntax error
BREAK-POINT.
ENDFORM .

Re: Why can't we pass data ref variable of type string to perform with USING import par TYPE REF TO data

former_member736527 — Tue, 30 Mar 2021 14:19:47 GMT

If you must use subroutines, then you can convert LR_STRING to TYPE REF TO DATA, and pass that to the subroutine

DATA: lr_string  TYPE REF TO string,
      lr_string1 TYPE REF TO data.
FIELD-SYMBOLS: <fs_temp> TYPE any.
CREATE DATA lr_string.
lr_string->* = 'String'.


CREATE DATA lr_string1 TYPE string.
ASSIGN lr_string1->* TO <fs_temp>.
<fs_temp> = lr_string->*. "basically putting LR_STRING (STRING) in LR_STRING1 (DATA)


PERFORM pass_string_as_im USING lr_string1.

FORM pass_string_as_im USING im_string TYPE REF TO data. " Syntax_Error-1
*im_string TYPE REF TO string. "Working
  FIELD-SYMBOLS: <fs_temp> TYPE any.
  ASSIGN im_string->* TO <fs_temp>.
  WRITE:/ <fs_Temp>.
ENDFORM .
<br>

Re: Why can't we pass data ref variable of type string to perform with USING import par TYPE REF TO data

matt — Tue, 30 Mar 2021 16:30:21 GMT

sandra.rossi
I'm reminded of this. Everything is Broken