Question

When compiling Embarcadero VirtualShellTools in Delphi 2007: http://embtvstools.svn.sourceforge.net/

function TShellIDList.InternalChildPIDL(Index: integer): PItemIDList;
{ Remember PIDLCount does not count index [0] where the Absolute Parent is     }
begin
  if Assigned(FCIDA) and (Index > -1) and (Index < PIDLCount) then
    Result := PItemIDList( PByte(FCIDA) 
                         + PDWORD(PByte(@FCIDA^.aoffset)
                                  +sizeof(FCIDA^.aoffset[0])*(1+Index))^)
  else
    Result := nil
end;

I get this error:

[Pascal Error] IDEVirtualDataObject.pas(1023): E2015 Operator not applicable to this operand type

What’s the problem with this code and what kind of type-casting do I need to do to actually make it work?

I get the same error on the following (less complex) routine:

function TShellIDList.InternalParentPIDL: PItemIDList;
{ Remember PIDLCount does not count index [0] where the Absolute Parent is     }
begin
  if Assigned(FCIDA) then
      Result :=  PItemIDList( PByte(FCIDA) + FCIDA^.aoffset[0])
  else
    Result := nil
end;

Answer 1

Pointermath was introduced in Delphi 2009. The best you can do in Delphi 2007 is to use Inc procedure instead:

function TShellIDList.InternalChildPIDL(Index: integer): PItemIDList;
{ Remember PIDLCount does not count index [0] where the Absolute Parent is     }
var
  Tmp, Tmp2: PByte;

begin
  if Assigned(FCIDA) and (Index > -1) and (Index < PIDLCount) then begin
    Tmp2:= PByte(@FCIDA^.aoffset);
    Inc(Tmp2, sizeof(FCIDA^.aoffset[0])*(1+Index));
    Tmp:= PByte(FCIDA);
    Inc(Tmp, PDWORD(Tmp2)^);
    Result := PItemIDList(Tmp);
  end
  else
    Result := nil
end;