How to build a generic ALV GRID DISPLAY

[miguelcrodrigues]

Hello there,
I'm trying to build a generic ALV Display function that can work to any case.
This is my progress right now.

"THIS IS THE CLASS DEFINITION
CLASS lcl_utils DEFINITION.
  PUBLIC SECTION.
    TYPES: BEGIN OF it_sel,
             sel1 TYPE string,
             sel2 TYPE string,
             sel3 TYPE string,
             sel4 TYPE string,
           END OF it_sel.

    TYPES: BEGIN OF it_field,
             name  TYPE string,
             prop  TYPE string,
             value TYPE int8,
           END OF it_sel.

    CLASS-METHODS:
      build_alv IMPORTING iv_table    TYPE tabname "TABLE TYPE
                          it_select   TYPE it_sel "INTERNAL TABLE WITH SELECT INSTRUCIONS
                          iv_cname     TYPE string "IDENTIFIER OF 'CUSTOM CONTROL' FROM PAINTER
                          it_fieldcat TYPE it_field "OPTIONAL - INTERNAL TABLE WITH THE FIELDCAT
                          iv_hotspot  TYPE string "OPTIONAL - FUNCIONT TO BE EXECUTED.
ENDCLASS.

------------------------

"THIS WOULD BE THE GENERIC METHOD
METHOD build_alv.
    DATA: lt_fieldcat TYPE lvc_t_fcat,
          lv_grid     TYPE REF TO cl_gui_alv_grid.

    IF iv_table IS NOT INITIAL.
      DATA: lt_generic TYPE TABLE OF iv_table.
      SELECT it_sel-sel1 FROM it_sel-sel2 WHERE it_sel-sel3 EQ it_sel-sel4 INTO TABLE @lt_generic.
      "RECIVE SELECT
    ENDIF.

    IF lv_grid IS INITIAL.
      lv_grid = NEW #( i_parent = NEW cl_gui_custom_container( container_name = iv_cname ) ).
      "RECIVE CONTAINER NAME

      CALL FUNCTION 'LVC_FIELDCATALOG_MERGE'
        EXPORTING
          i_structure_name       = iv_table
        CHANGING
          ct_fieldcat            = lt_fieldcat
        EXCEPTIONS
          inconsistent_interface = 1
          program_error          = 2
          OTHERS                 = 3.
      IF sy-subrc <> 0.
* Implement suitable error handling here
      ENDIF.

      IF it_fieldcat IS NOT INITIAL.
        LOOP AT it_fieldcat.
          lt_fieldcat[ fieldname = it_fieldcat-name ]-it_fieldcat-prop = it_fieldcat-value.
          "RECIVE NAME PROPERTY AND VALUE
        ENDLOOP.
      ENDIF.


      me->lv_grid->set_table_for_first_display(
        EXPORTING
          i_structure_name = iv_table
          "RECIVE TABLE NAME TYPE
          CHANGING
            it_fieldcatalog = lt_fieldcat
            it_outtab = lt_generic
            EXCEPTIONS
              invalid_parameter_combination = 1
              program_error = 2
              too_many_lines = 3
              OTHERS = 4
      ).

      IF iv_hotspot IS NOT INITIAL.
        lv_grid->register_edit_event( i_event_id = cl_gui_alv_grid=>mc_evt_modified ).
        SET HANDLER iv_hotspot FOR lv_grid.
        "RECIVE FUNCION NAME
      ENDIF.
    ELSE.
      lv_grid->refresh_table_display( ).
    ENDIF.
  ENDMETHOD.

The problem now is that I don't now the 'TYPE' of an ABAP instruction, of course sel1, sel2... cant be a string, but how can I say that is a instruction of code or part of the code? Can I send a SQL instructions through parameter of a function?
If anyone has done, or can see a way to fix my design I would be very much appreciated.