Dynamic ITAB copy problem with field type P

Question

Hello everyone
I need to copy the structure of an internal table that is pass by reference into a method.
Actually everything is fine else than the field type P with decimal is not created properly in the new itab.
Scenario:
An internal table is pass by reference to a method. We need to trait the data without modifying the original table. The Idea is to copy the structure and the data of the referenced internal table into an internal table created dymanically in the method.
Here is what I did and working fine when there are no field of data type "CURR".
Extract the structure of the reference data.
Create a dynamic internal table.
So far so good. Everything seams to work fine. BUT
when I am trying to copy the data from the reference table to the just created internal table the field with data type "CURR" doesn't work.
Here is my example:
FIELD-SYMBOLS: <FS_TABLE> TYPE STANDARD TABLE,
               <TMP_TABLE> TYPE STANDARD TABLE,
               <LS_TMP_TABLE> TYPE ANY,
               <LS_TABLE>     TYPE ANY,
               <LS_VALUE>     TYPE ANY.
DATA: lt_data      TYPE STANDARD TABLE OF vbak,
      ls_data      LIKE LINE OF lt_sortfield,
      ref_data     TYPE REF TO data,
      l_structure  TYPE REF TO DATA,
      lv_ltname    TYPE string.               
select * from vbak UP TO 10 rows INTO CORRESPONDING FIELDS OF TABLE lt_data.
* --- Assign the reference variable to the table
* ---- Only use to simulate a parameter that is assign to a reference to a internal table
unassign <FS_TABLE>.
lv_ltname = 'lt_data[]'.
ASSIGN (lv_ltname) to <FS_TABLE>.
GET REFERENCE OF <FS_TABLE>[] INTO ref_data.
* --- Assign the reference to the field-symbol
UNASSIGN <FS_TABLE>.
ASSIGN ref_data->* TO <FS_TABLE>.
* --- Create a working area for the reference table to a field-table
CREATE DATA l_structure LIKE LINE OF <FS_TABLE>.
ASSIGN l_structure->* TO <LS_TABLE>.
* --- Retrieve the structure of the field-symbol pointing to the internal table
DATA: lr_tabledescr   TYPE REF TO cl_abap_tabledescr,   " Internal Table description
      _r_structdescr  TYPE REF TO cl_abap_structdescr.
lr_tabledescr ?= cl_abap_tabledescr=>describe_by_data( <fs_table> ).
_r_structdescr ?= lr_tabledescr->get_table_line_type( ).
* --- Read internal table structure to create dynamic internal table
data: ls_struc like LINE OF _r_structdescr->components,
      xfc           type lvc_s_fcat,
      ifc           type lvc_t_fcat.
* --- Why the field (component) NETWR length is now 8 instead of 15?
LOOP AT _r_structdescr->components into ls_struc.
  clear xfc.
  xfc-fieldname = ls_struc-name .
  xfc-datatype  = ls_struc-type_kind.
  xfc-inttype   = ls_struc-type_kind.
  xfc-intlen    = ls_struc-length.
  xfc-decimals  = ls_struc-decimals.
  append xfc to ifc.
ENDLOOP.
DATA:   dy_table      type ref to data,
* --- Create dynamic internal table
call method cl_alv_table_create=>create_dynamic_table
  EXPORTING
    it_fieldcatalog = ifc
  IMPORTING
    ep_table        = dy_table.
* --- assign reference internal table to Field-symbol
assign dy_table->* to <tmp_table>.
unassign <ls_tmp_table>.
DATA: ls_tmp_struc type REF TO DATA.
CREATE DATA ls_tmp_struc like LINE OF <tmp_table>.
ASSIGN ls_tmp_struc->* TO <ls_tmp_table>.
Loop at <fs_table> INTO <LS_TABLE>.
MOVE-CORRESPONDING <ls_table> TO <ls_tmp_table>.
APPEND <ls_tmp_table> TO <tmp_table>.
ENDLOOP.
* <fs_table>-netwr length is 15
* <ls_tmp_table>-netwr length is 8
* ??????????? Why the length is different?
* ??????????? It should a structure copy and have the
* ??????????? same length
I use VBAK as example, and the field NETWR is using data type "NETWR_AK" where it us a data type "CURR" with length 15 and decimal 2.
When reading the structure, the method get_table_line_type of the class cl_abap_tabledescr return a length of 8 instead of 15.
Any idea how to get the exact structure of a variable that is refering to a data type?
Regards
Daniel

Answer 1

Hello Everyone
Thank you for your replies.
I think I didn't explain myself clearly.
My goal is to be able to create an exact  structure copy of a "Type ref to data" into a new internal table that is not defined yet.
Example:
  A method contain a parameter that is a ref to DATA type.
  That parameter is refering to an internal table from the calling program.
  Now I want to create an internal table into the method where this one will be an exact structure copy of the parameter.
  So, lets put some name here.
  parameter: ip_data type ref to data.
  FIELD-SYMBOLS: <FS_REF_DATA> TYPE STANDARD TABLE,
                                <FS_CP_DATA>  TYPE STANDARD TABLE.
ASSIGN ip_data->* TO <FS_REF_DATA>.
" some code to assign the same structure to <FS_CP_DATA> from <FS_REF_DATA>
" than copy the data from <FS_REF_DATA> to <FS_CP_DATA>.
<FS_CP_DATA> [ ] = <FS_REF_DATA> [ ].  " This is working if no type P with decimal exist into the structure
" Than I can play with the data of <FS_CP_DATA> without modifying the data of <FS_REF_DATA>.
My problem would be solved if I can create dynamically an internal table that has an exact structure copy of the passed parameter.
Regards
Daniel