Variant Record Sizes..

From: Ganesh Ramasivan (ganesh.ramasivan_at_gdcanada.com)
Date: 08/19/04 

Date: 19 Aug 2004 11:48:25 -0700

Hello,

I am having a hard time understanding variant records with regard to
memory usage. Does the size of the record become the size of the
largest element in that record?

So in case of the example below, is the size of the Test_Record 2
bytes, even though the "use 8" clause has been specified as the other
element of the record specifies "use 16".

Any input will be appreciated.

Thanks,

Ganesh

------------------------
with ada.text_io;

procedure Variant is

  package int_io is new ada.text_io.integer_io(Integer);

  type TEST_STATE_CHOICE is (DISABLE, ENABLE);
  for TEST_STATE_CHOICE'SIZE use 8;

  type OTHER_STATE_CHOICE is (ON, OFF);
  for OTHER_STATE_CHOICE'SIZE use 16;

  type TEST_ICP_POI_MESSAGE_ID_CHOICE is (STATE_1, STATE_2);
  for TEST_ICP_POI_MESSAGE_ID_CHOICE'SIZE use 8;

  type TEST_ICP_POI_MESSAGE_TYPE
   (ICP_POI_MESSAGE_ID : TEST_ICP_POI_MESSAGE_ID_CHOICE) is
    record
      case ICP_POI_MESSAGE_ID is
        when STATE_1 =>
          ICP_STATE : TEST_STATE_CHOICE;
        when STATE_2 =>
          PING_STATE : OTHER_STATE_CHOICE;
        when others =>
          null;
      end case;
    end record;
    
    pragma pack (TEST_ICP_POI_MESSAGE_TYPE);
    
    Test_Record : TEST_ICP_POI_MESSAGE_TYPE(STATE_1);
    Record_Size : INTEGER := 0;
begin
  Record_Size := Test_Record'Size/8;
  ada.text_io.put("Record Size = ");
  int_io.put(Record_Size); ada.text_io.new_line;
end Variant;
--------------------------

Relevant Pages

  • Calculation order
    ... I noted with regard to a UDF I have to convert Roman to Arabic numerals, ... What did make a difference was eliminating the Type specification (or changing ... Function Arabic (rg as variant) as long ...
    (microsoft.public.excel.programming)
  • Which is better?
    ... but writing to a range of cells with a variant array is supposed to be fast. ... Is looping through all the individual cells a better option? ... Any help in this regard will be appreciated ...
    (microsoft.public.excel.programming)