program t78_setfield;

{ t78 -- a SET field of a record: assignment and membership.

  CALC.INC:161 is the first statement inside `with Sheet[I,J] do':

      CellStatus := [Txt];

  CellStatus is `set of Attributes' (0..5, so ONE byte), NOT the default
  32-byte `set of Char' that an untyped constructor becomes.  The target
  supplies the base and size; the constructor's bytes are known at compile
  time and are stored at symbol+boff (a constant-index element) or through DI
  (a run-time-indexed one).

  `in' is the observation: a CODE-resident set (literal or typed constant)
  still folds at compile time, while a set FIELD is tested at run time by
  loading its byte and masking the element's bit. }

type
   Attr = (Constant, Formula, Txt, OverWritten, Locked, Calculated);
   Cell = record
      Status : set of Attr;
      N : integer;
   end;

var
   sh : array [1..2, 1..3] of Cell;

begin
   with sh[1,1] do
   begin
      Status := [Txt];
      N := 5
   end;
   with sh[1,1] do
      if Txt in Status then writeln ('txt') else writeln ('no-txt');
   with sh[1,1] do
      if Locked in Status then writeln ('locked') else writeln ('not-locked');

   (* N sits immediately after the one-byte Status.  Set it FIRST, then the
      set: a store that used the default 32-byte length would run over N and
      zero it. *)
   sh[2,3].N := 7;
   sh[2,3].Status := [Locked, Calculated];
   if Locked in sh[2,3].Status then writeln ('l2') else writeln ('nl2');
   if Txt in sh[2,3].Status then writeln ('t2') else writeln ('nt2');

   (* the fields after the set were not clobbered *)
   writeln (sh[1,1].N);
   writeln (sh[2,3].N)
end.