Hello all,

I am trying to use generics but compilation fails. Whan I try to use unit with my generic class in my real project I get "Fatal: Internal error 200204175" error.
When I try to use it in empty Lazarus application (Unit1.pas) and I put -----
procedure TForm1.Button1Click(Sender: TObject);
var

  lst:  specialize TTwoValuesList<UnicodeString>;

begin
end;
-----
I get these errors:
-----
Unit1.pas(29,17) Error: Forward declaration not solved "constructor TTwoValuesList$UnicodeString.Create;"
Unit1.pas(30,16) Error: Forward declaration not solved "destructor TTwoValuesList$UnicodeString.Destroy;"
Unit1.pas(32,15) Error: Forward declaration not solved "TTwoValuesList$UnicodeString.AddString(UnicodeString,UnicodeString);" Unit1.pas(33,14) Error: Forward declaration not solved "TTwoValuesList$UnicodeString.GetS1(LongInt):UnicodeString;" Unit1.pas(34,14) Error: Forward declaration not solved "TTwoValuesList$UnicodeString.GetS2(LongInt):UnicodeString;" Unit1.pas(35,14) Error: Forward declaration not solved "TTwoValuesList$UnicodeString.Count:LongInt;"
Unit1.pas(36,14) Error: Forward declaration not solved "TTwoValuesList$UnicodeString.GetS2(UnicodeString,Boolean="FALSE"):UnicodeString;" Unit1.pas(47) Fatal: There were 7 errors compiling module, stopping -----

my generic class is in another (not Unit1.pas) unit looks like this:
-----
type
  generic TTwoValuesList<TVal> = class
  type private
    PTwoVal = ^TTwoVal;
    TTwoval = record
      FS1: TVal;
      FS2: TVal;
    end;
  var private
    FLst: TFPList;
  public
    constructor Create;
    destructor Destroy;
    procedure AddString(S1: TVal; S2: TVal);
    function GetS1(i: Integer): TVal;
    function GetS2(i: Integer): TVal; overload;
    function Count: Integer;
    function GetS2(S1: TVal; isSorted: Boolean = false): TVal; overload;
  published
    property Items: TFPList read FLst;
  end;
-----

What am I doing wrong?

Regards,
Zilvinas Ledas

Sorry, I forgot to mention I am using
Free Pascal Compiler version 2.3.1 [2009/09/08] for i386 (don't know how to get more specific version info...)

I would try to use a named type:
type
   TTwoUnicodeValuesList = specialize TTwoValuesList<UnicodeString>;
procedure TForm1.Button1Click(Sender: TObject);
var
  lst:  TTwoUnicodeValuesList;
begin
end;

Vincent

Thanks, it works with named type.
Is using not named specializations is some kind of "not implemented yet" part? :)

Regards
Zlvinas Ledas

Žilvinas Ledas wrote

Thanks, it works with named type. Is using not named specializations is some kind of "not implemented yet" part? :)

No it's a design choice to more easily reuse separate (but equal) specializations.

Micha

Well, the internal error is in any case a bug, so if this appears also with the latest (trunk) version, a bug report would be useful.

Tomas

Tomas Hajny wrote

Well, the internal error is in any case a bug, so if this appears also with the latest (trunk) version, a bug report would be useful.

I didn't see an internal error? But a more descriptive message would be useful ('specialization not allowed in this context' or so?).

Micha

The original post mentioned "Fatal: Internal error 200204175".

Tomas

Yes, I had an internal error and now I know why - I used specialization
in function params. This gives internal error:
procedure asdasd(something: specialize TTwoValuesList<UnicodeString>);
begin
end;

I'll make a bug report tomorow or a day after.

And yes, I think a descriptive message saying to use typed specialization would be nice for those using generics first time.

Regards,
Zilvinas