Hi,

I try to do exactly the same as show here:

QUOTE:
http://svn.freepascal.org/svn/fpc/trunk/packages/fcl-stl/src/gvector.pp

generic TVector<T> = class
  ... ...
  type
    TVectorEnumerator = class
    private
      FVector: TVector;
      FPosition: SizeUInt;
      FFirstDone: Boolean;
      function GetCurrent: T; inline;
    public
      *constructor Create(AVector: TVector);*
      function MoveNext: Boolean; inline;
      property Current: T read GetCurrent;
    end;
  ... ...
  public

My code:

generic TTreap<TKey, TValue> = class
  ... ...
  type
    TTreapEnumerator = class
      FStack: TStack;
      FCurrent: PNode;
    public
      *constructor Create(ATreap: TTreap);*
      destructor Destroy; override;
      function MoveNext: Boolean;
      property Current: PNode read FCurrent;
    end;
  ... ...
  private

Error message I got is: Error: Generics without specialization cannot be used as a type for a variable

Then I found this: http://bugs.freepascal.org/view.php?id=19499&history=1

I wonder if this bug's fix is release or not? How does the TVector class compile with this problem?

Thanks!
Xiangrong

Hi,

I missed the key point. This bug should be fixed in 2.7.1, but I am now using 2.6.0. Now there is another problem:

If I change my code to this:

      TTreapEnumerator = class
        FStack: TStack;
        FCurrent: PNode;
      public
*        constructor Create(root: PNode);*
        destructor Destroy; override;
        function MoveNext: Boolean;
        property Current: PNode read FCurrent;
      end;

The problem is gone, because PNode is not a generic class, but only a record. However, the following errors are generated:

Error: Forward declaration not solved "constructor THistogram.TTreap$Char$LongInt.TTreapEnumerator.Create(PNode);" Error: Forward declaration not solved "destructor
THistogram.TTreap$Char$LongInt.TTreapEnumerator.Destroy;" Error: Forward declaration not solved
"THistogram.TTreap$Char$LongInt.TTreapEnumerator.MoveNext:Boolean;"

THistogram is defined as:

  THistogram = class(specialize TTreap<Char, Integer>)
  protected
    function DefaultTraverser(Key: Char; Value: Integer): Boolean; override;
    procedure DefaultDisposer(Value: Integer); override;
    function DefaultUpdater(Key: TKey; Value: TValue; IsNew: Boolean):
Boolean; override;
  public
    MKey: Char;
    Max: Integer;
    constructor Create; override;
  end;

I think there is no need to define TTreapEnumerator in THistogram again, right?

Xiangrong

2013/3/22 Xiangrong Fang

"Xiangrong Fang" wrote

Hi, I missed the key point. This bug should be fixed in 2.7.1, but I am now

using 2.6.0. Now there is another problem:

record. However, the following errors are generated:

2.6.x does not support nested types in generics. Generic fixes and improvements are only found in 2.7.1 as most of them were to invasive to be merged back.

Regards,
Sven

2013/3/22 Sven Barth

OK, then why this error happened:

demo2.lpr(76,13) Error: Incompatible types: got
"TRoller.TTreap$PPerson$Byte" expected "TRoller"

The problematic lines are:

=== demo2.lpr ===

var
  n: TRoller.PNode;
  r1, r2: TRoller;
begin
  r1 := TRoller.Create;
  with r1 do begin
    ... ...
 *   r2 := r1.Copy(@OrderByAge);*
    ... ...
  end;
end.

=== treap.pas ===

function TTreap.Copy(Comp: TComparator): TTreap;
var
  n: PNode;
begin
  if Comp = nil then Comp := FComparator;
  Result := TTreap.Create;
  Result.Comparator := Comp;
  for n in Self do Result.Insert(n^.Key, n^.Value);
end;

I don't see there are "nested types" and why there is a type named: TRoller.TTreap$PPerson$Byte?
Shouldn't be either
TRoller or TTreap$PPerson$Byte but not both?

Thanks,
Xiangrong

AFAIR there was also a problem with result types in generics. Could you please test your code with 2.7.1 to be sure?

Regards,
Sven

I didn't see a DEB package for 2.7.1. I am currently using 2.6.0. Can I compile 2.7.1 from source with 2.6.0?

2013/3/22 Sven Barth

Xiangrong Fang wrote

I didn't see a DEB package for 2.7.1. I am currently using 2.6.0. Can I compile 2.7.1 from source with 2.6.0?

Yes. In fact you MUST compile with 2.6.0 (or 2.6.2).

Go to the directory of your 2.7.1 source and execute "make all". If your test code does only depend on the RTL units then you can compile your example without an installation from within the top level directory using this command:

=== command begin ===

./compiler/ppc386 -n -Furtl/units/i386-linux -viwn -FEsomeoutputdir yourunit.pas

=== comand end ===

If you compiled a 64-bit version you need to use this instead:

=== command begin ===

./compiler/ppcx64 -n -Furtl/units/x86_64-linux -viwn -FEsomeoutputdir yourunit.pas

=== command end ===

Regards,
Sven

Hi Sven,

My unite uses contnrs unit, how can I instruct the compiler to use the contnrs unit (also the Classes and sysutils units) of v2.7.1? I have already built 2.7.1 and now try to compile my program in the fpc source dir as you told.

Thanks

2013/3/22 Xiangrong Fang

The Classes and SysUtils unit should be no problem if you used the command I gave you (if you look into the "rtl/units/i386-linux" (or "rtl/units/x86_64-linux") directory you'll see the files "classes.ppu" and "sysutils.ppu"). For the compiler to find unit "Contnrs" you need to add "-Fupackages/fcl-base/units/i386-linux" (or
"-Fupackages/fcl-base/units/x86_64-linux") to the command.

Regards,
Sven

I got this error now:

treap.pas(311,48) Error: Illegal expression
treap.pas(311,50) Error: Illegal expression
treap.pas(311,50) Fatal: Syntax error, ";" expected but "ordinal const"
found
Fatal: Compilation aborted

The line that generated this error is:

  if Result = NullNode then begin
    if (Rank = 0) or (Anchor < Key) then Rank += 1;   <-- error here
    Result := nil;
  end;

It seems that the += operator is not supported anymore?? Is there any switches in the new 2.7.1?

2013/3/23 Sven Barth

The C style operators need to be enabled using a switch which is AFAIK either normally done in the fpc.cfg or by Lazarus. Nevertheless the command line switch you need is "-Sc".

Regards,
Sven

I think the problem is not fixed in 2.7.1:

~/fpc $ ./compiler/ppcx64 -n -Furtl/units/x86_64-linux -Fupackages/fcl-base/units/x86_64-linux -viwn -FE/home/xrfang -Sc demo2.lpr Target OS: Linux for x86-64
Compiling demo2.lpr
Compiling treap.pas
demo2.lpr(88,11) Error: Incompatible types: got "TTreap$2$crc94C56373" expected "TRoller"
demo2.lpr(98) Fatal: There were 1 errors compiling module, stopping Fatal: Compilation aborted

2013/3/24 Sven Barth

Aha! Now that I've seen your code I know where the problem is.

Your TRoller class is declared like this:

=== code begin ===

type
   TRoller = class(specialize TTreap<PPerson, Byte>)
     //...
   end;

=== code end ===

So TRoller is a child class of TTreap<PPerson, Byte> and thus the result type of Copy is TTreap<PPerson, Byte>. This is basically not related to generics, but to normal class inheritance. To solve this you need to adjust your TTreap.Copy in such a way that it doesn't use "TTreap.Create", but "ClassType.Create" and you must use TRoller's Copy then this way:

=== code begin ===

r2 := r1.Copy as TRoller;

=== code end ===

Regards,
Sven

Thanks Sven :)

2013/3/24 Sven Barth