Dynamic type variable creation

Question

I want to create a variable with a pre-defined TYPE, but the latter will only be known at runtime.
For instance:
Consider that I my DEFINITIONS1 include file is:
TYPES: BEGIN OF type1,
                field1 TYPE i,
                field2 TYPE i,
                field3 TYPE i,
            END OF type1,
              BEGIN OF cust_type_A,
                   INCLUDE TYPE type1.
TYPES:       erdat TYPE vbak-erdat,
              END OF cust_type_A,
             BEGIN OF cust_type_B,
                   INCLUDE TYPE type1.
TYPES:       fkdat TYPE vbrk-fkdat,
              END OF cust_type_B.
Than I have the following code (assume "letter" is a character parameter I receive, either 'A' or 'B'):
INCLUDE definitions1.
DATA: z TYPE REF to data.
FIELD-SYMBOLS: <fs> TYPE ANY.
DATA str type string.
CONCATENATE 'MY_CUST_TYPE_' letter INTO str.
CREATE DATA z TYPE (str).
*  ASSIGN z->* TO <fs>.
Why is that that the CREATE DATA z TYPE (str) statement fails ?
How, then, I create a variable/field symbol from a specific type, which will only be known at runtime ?
Thanks
Avraham

Answer 1

Check this code to create a dynamic type at run time using the RTTS - Run Time Type Services.
DATA: lo_struct   TYPE REF TO cl_abap_structdescr,
      lo_element  TYPE REF TO cl_abap_elemdescr,
      lo_new_type TYPE REF TO cl_abap_structdescr,
      lo_data     TYPE REF TO data,
      lt_comp     TYPE cl_abap_structdescr=>component_table,
      lt_tot_comp TYPE cl_abap_structdescr=>component_table,
      la_comp     LIKE LINE OF lt_comp.
DATA: lc_num TYPE char10.
* field symbols to access the dynamic table
FIELD-SYMBOLS: <f_line>  TYPE ANY,
               <f_field> TYPE ANY.
PARAMETERS: p_a RADIOBUTTON GROUP rd1,
            p_b RADIOBUTTON GROUP rd1.
START-OF-SELECTION.
  DO 3 TIMES.
    lc_num = sy-index.
    CONDENSE lc_num.
*   Element Description
    lo_element ?= cl_abap_elemdescr=>describe_by_name( 'INT4' ).
*   Field name
    CONCATENATE 'FIELD' lc_num INTO la_comp-name.
*   Field type
    la_comp-type = cl_abap_elemdescr=>get_p(
                      p_length   = lo_element->length
                      p_decimals = lo_element->decimals ).
*   Filling the component table
    APPEND la_comp TO lt_tot_comp.
    CLEAR: la_comp.
  ENDDO.
  IF p_a = 'X'.
*   Element Description
    lo_element ?= cl_abap_elemdescr=>describe_by_name( 'ERDAT' ).
*   Field name
    la_comp-name = 'ERDAT'.
*   Field type
    la_comp-type = cl_abap_elemdescr=>get_p(
                      p_length   = lo_element->length
                      p_decimals = lo_element->decimals ).
*   Filling the component table
    APPEND la_comp TO lt_tot_comp.
    CLEAR: la_comp.
  ELSEIF p_b = 'X'.
*   Element Description
    lo_element ?= cl_abap_elemdescr=>describe_by_name( 'FKDAT' ).
*   Field name
    la_comp-name = 'FKDAT'.
*   Field type
    la_comp-type = cl_abap_elemdescr=>get_p(
                      p_length   = lo_element->length
                      p_decimals = lo_element->decimals ).
*   Filling the component table
    APPEND la_comp TO lt_tot_comp.
    CLEAR: la_comp.
  ENDIF.
* 3. Create a New Type
  lo_new_type = cl_abap_structdescr=>create( lt_tot_comp ).
* 5. data to handle the new table type
  CREATE DATA lo_data TYPE HANDLE lo_new_type.
* 6. New internal table in the fieldsymbols
  ASSIGN lo_data->* TO <f_line>.
Regards,
Naimesh Patel