[fpc-pascal] problem with interface (OOP not widget)

Wed, 23 Jan 2008 00:14:00 -0800 

Hi all,

I got problem with the code below.

--->8--- begin code --->8---

program test_intf_query;

{$IFDEF FPC}
  {$MODE OBJFPC}{$H+}
{$ENDIF}

uses
  Classes;

type
  TPLFieldType = (plftUnknown, plftString, plftSmallint, plftInteger,
    plftWord, plftBoolean, plftFloat, plftCurrency, plftBCD, plftDate,
    plftTime, plftDateTime, plftBytes, plftVarBytes, plftAutoInc,
    plftBlob, plftMemo, plftGraphic, plftFmtMemo, plftParadoxOle,
    plftDBaseOle, plftTypedBinary, plftCursor, plftFixedChar,
    plftWideString, plftLargeint, plftADT, plftArray, plftReference,
    plftDataSet, plftOraBlob, plftOraClob, plftVariant, plftInterface,
    plftIDispatch, plftGuid, plftTimeStamp, plftFMTBcd,
    plftFixedWideChar, plftWideMemo, plftOraTimeStamp, plftOraInterval);

  ISimple = interface
  ['{24811FF3-4F01-4601-AC5C-22A5B5D46928}']
    function ShowSomething: Integer; cdecl;
    function GetIsBlob: Boolean; cdecl;
  end;

  TSimple = class(TInterfacedObject, ISimple)
  private
    FDataType: TPLFieldType;
  protected
    { ISimple implementation }
    function ShowSomething: Integer; cdecl;
    function GetIsBlob: Boolean; cdecl;
  end;

{ query ISimple }
function QuerySimple(const OnChange: TNotifyEvent = nil): ISimple;
  cdecl;
begin
  Result := TSimple.Create;
end;

{*** TSimple ***}

function TSimple.ShowSomething: Integer; cdecl;
begin
  Writeln('Message from ISimple');
  Result := 0;
end;

function TSimple.GetIsBlob: Boolean; cdecl;
begin
  Result := FDataType in [
            plftBytes, plftVarBytes, plftBlob, plftMemo, plftGraphic,
            plftFmtMemo, plftParadoxOle, plftDBaseOle, plftTypedBinary,
            plftOraClob, plftOraClob, plftWideMemo
            ];
end;

{*** main program ***}

var
  FSimple: ISimple;

begin
  FSimple := QuerySimple(nil);
  //FSimple := TSimple.Create;

  FSimple.ShowSomething;
end.

--->8--- end code --->8---

FPC failed to compile it. The compiler complained with this message:
test_intf_query.pas(56,26) Error: range check error in set constructor or duplicate set element
With wonder, I commented line 56. Then the compiler complained with this message: 

test_intf_query.pas(66,14) Fatal: Internal error 200408162
Weird. So, I commented line 66 and uncommented line 67 (just to make it compilable). It compiled fine. But when it's executed, it ended up with AV. Here's the output: 

[EMAIL PROTECTED]:~/Programs$ ./test_intf_query
Message from ISimple
An unhandled exception occurred at $0804816C :
EAccessViolation : Access violation
  $0804816C
I'm using FPC 2.2.0, 2.2.1, and 2.3.1 on Ubuntu Gutsy i386. I thought it was the problem with FPC for Linux, so I tried it with FPC 2.2.0 on Windows (on exact machine). But, same errors persist on all FPC versions. :(
IMHO, the above code (before modifications to make it compilable) should be fine. I can't see nothing wrong with it. To make sure, I compiled the code using Delphi 7 and Turbo Delphi Explorer. Both Delphi compiled fine and the executable output run without problem.
The actual program actually much bigger than the above, it's a part of a big framework I've been working on. I cut it and made much simpler to isolate the problem. FYI, the framework itself initially written using Delphi 7 and works well. Now, I'm trying to port it to FPC. 

Hints? TIA.

-Bee-

has Bee.ography at:
http://beeography.wordpress.com
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