How to check validity of data reference

Question

Hello everybody,
in my application I use a help class to buffer data objects.
This class contains one attribute which is an internal table ( columns: DATAID and DATAREF )
I use this databuffer to transport data between different classes.
Now I did the following mistake:
First I call the method 'METH_CHECK'. As import parameter I pass a reference to my databuffer class.
In method 'METH_CHECK' I call a function module 'FUNC_1' passing my reference to my databuffer class.
In 'FUNC_1'  I declare a local variable 'lv_value'.
Then I use the statement 'GET REFERENCE OF lv_value' and save this reference into my databuffer class.
After processing functions / methods I´m back at the point where 'METH_CHECK' was called.
When I check my databuffer class, I´ve got one entry in it.
The reference I saved while processing 'FUNC_1' . But the referenced data has already be freed ( remember, it was a local variable ).
In the debugger I see the column where I save the references to data objects.
The field value has changed from a valid reference to i.e. 'FREED ITAB: 5'...
OK, I know what is wrong... No problem in my application, but I want to clean
this entry... How can I check this...
I can not check like
  LOOP AT me->buffer INTO wa_buffer.
    IF wa_buffer-data IS INITIAL.
      DELETE...
    ENDIF.
  ENDLOOP.
or
  LOOP AT me->buffer INTO wa_buffer.
    IF wa_buffer-data CP 'FREED'.
      DELETE....
    ENDIF.
  ENDLOOP.
How can I notice an invalid reference at this point?
Thank you very much,
Oliver Seifer

Answer 1

Hello Oliver,
Another approach might be to avoid any dependency to the caller at all.
Regards
  Klaus
data:
    buffer_Reference  type ref to data.
field-symbols:
   <buffer_Data> type data.
create data buffer_Reference like i_Value.
assign buffer_Reference to <buffer_Data>.
<buffer_Data> = i_Value.