ABAP--动态创建局部类型的变量

REPORT ZDANY_DYN_LOCAL_TYPES.
****************** hardcoded "old style" local type*******************
* This is a normal hardcoded local type
types : begin of typ_hardcoded,
      l_count type i,
      lt_sflight type sflight.
types : end of typ_hardcoded.
* create a table based on hardcoded type
data : lt_hardcoded type table of typ_hardcoded.
****************** dynamic "new wave" local type *******************
types: typ_count type i.
field-symbols : <lt_dynamic> type any table.
data: dref type ref to data,
  itab_type type ref to cl_abap_tabledescr,
  struct_type type ref to cl_abap_structdescr,
  elem_type type ref to cl_abap_elemdescr,
  comp_tab type cl_abap_structdescr=>component_table,
  comp_fld type cl_abap_structdescr=>component.
* We read information about each fields of SFLIGHT (see ABAP FAQ #2)
struct_type ?= cl_abap_typedescr=>describe_by_name( 'SFLIGHT' ).
* We also need the information about the type "typ_count", note that
* we should use class cl_abap_elemdescr instead of cl_abap_typedescr
elem_type ?= cl_abap_elemdescr=>describe_by_name( 'TYP_COUNT' ).
* we read all fleids of SFLIGHT and create a component table
comp_tab = struct_type->get_components( ).
* We add manually the counter
comp_fld-name = 'L_COUNT'.
comp_fld-type = elem_type.
insert comp_fld into comp_tab index 1.
* we create the structure
struct_type = cl_abap_structdescr=>create( comp_tab ).
* ... and the internal table
itab_type = cl_abap_tabledescr=>create( struct_type ).
* The new thing here is the "type handle" which create a pointer to a handle
create data dref type handle itab_type.
* we finally assign a field symbol to the pointer because we cannot directly access a pointer.
assign dref->* to <lt_dynamic>.
* At the end of this small program, internal table lt_hardcoded and lt_dynamic are the same