Following code causes error "Operator is not overloaded: "TObject" < "TObject""
How to make it work?

program generictest2;
{$mode objfpc}{$H+}
uses
   fgl;
operator < (a: TObject; b: TObject): boolean;
begin
   result := PtrInt(a) < PtrInt(b);
end;
type
   TMyMap = specialize TFPGMap <TObject, TObject>;
begin
end.

2011/1/20 Alex Shishkin :

AFAIK TFPGMap can be specialized only with types which have the relational operators predefined by the compiler. See also: http://bugs.freepascal.org/view.php?id=15480

You can take a look on this container lib, which might be helpful for your task: http://code.google.com/p/fprb/wiki/heContnrs

20.01.2011 22:18, Honza пишет:

As I understand problem is in the compiler. It cant use overloaded
operator if it was defined after generic.
BTW this code compiles successfully.
program generictest2;
{$mode objfpc}{$H+}
operator > (a: TObject; b: TObject): boolean;
begin
   result := PtrInt(a) > PtrInt(b);
end;
type
   generic TComparator <T> = class
     class function Compare(a,b:T): Integer;
   end;
class function TComparator.Compare(a, b: T): Integer;
begin
   if a>b then
     Result := 1
   else if b>a then
     Result := -1
   else
     Result :=0;
end;
type
   TObjectComparator = specialize TComparator<TObject>;
begin

end.
Data can be any type but Key only "native comparable". If drop TFPGMap.KeyCompare along with DataCompare leaving only custom comparison it will work with any Key type.

You can take a look on this container lib, which might be helpful for your task: http://code.google.com/p/fprb/wiki/heContnrs

Good lib, but Lazarus codetools does not support nested classes as for now.

2011/1/20 Alex Shishkin :

As I understand problem is in the compiler. It cant use overloaded operator if it was defined after generic.

AFAIK exactly that is the problem and that's why TFPGMap can't cope with some types.

That's unfortunately a thing I can't help you with.

Another good one: http://code.google.com/p/stlpascal/ STLPascal Uses pattern commonly used by C++ STL, but fortunately written in a much more readable way. It has more data structures than heContnrs, but missing the BTree implementation. Really, IMHO somebody's got to merge all of these libraries (including fgl).

21.01.2011 0:26, leledumbo пишет:

stlpascal released under GPLv3 but fpc libraries under modified LGPL. If stlpascal will change license to modified LGPL it will be good to see it in fcl.

Please report this bug to the tracker.

Best regards,
Paul Ishenin

21.01.2011 3:07, Paul Ishenin пишет:

Also please see http://bugs.freepascal.org/view.php?id=18573, this related with generics to.
Alex