It fails because the operators < and > are not defined for TObject,
which is assumed by TFPGMap<TKey, TValue>.KeyCompare().
As a makeshift you can implement a record type to wrap TObject and
define these operators for it. See the attached file for an example.
Hope it helps.
On April 26, at 16:45, ZHANG Dao-yuan wrote:
>> program moi;
>> {$mode objfpc}
>> uses fgl;
>> type
>> tSI= specialize tFpGMap<integer, tObject>;
>> // tIS= specialize tFpGMap<tObject, integer>;
>> begin
>> end.
>
> Hi,
> I'm trying to use template in fpc 2.6.0. I can map class type as value
> as above code can be compiled. But if I uncomment the declaration of tIS
> -- map class type as key, fpc fail to compile and print out these error
> msgs:
>
> Error: Operator is not overloaded: "TObject" < "TObject"
> Error: Operator is not overloaded: "TObject" > "TObject"
> t.pas(10) Fatal: There were 2 errors compiling module, stopping
> Fatal: Compilation aborted
> Error: /usr/bin/ppcx64 returned an error exitcode (normal if you did not
> specify a source file to be compiled)
>
> Any way to resolve it?
> _______________________________________________
> fpc-pascal maillist - fpc-pascal@lists.freepascal.org
> http://lists.freepascal.org/mailman/listinfo/fpc-pascal
--
Best Regards,
JC Chu
{$MODE DELPHI}
uses Fgl;
type
TObjectRec = record
Value: TObject;
class operator LessThan(lhs, rhs: TObjectRec): Boolean;
class operator GreaterThan(lhs, rhs: TObjectRec): Boolean;
class operator Implicit(obj: TObject): TObjectRec;
class operator Implicit(rec: TObjectRec): TObject;
end;
TTest = TFPGMap<TObjectRec, Integer>;
class operator TObjectRec.LessThan(lhs, rhs: TObjectRec): Boolean;
begin
Exit(NativeInt(lhs) < NativeInt(rhs));
end;
class operator TObjectRec.GreaterThan(lhs, rhs: TObjectRec): Boolean;
begin
Exit(NativeInt(lhs) > NativeInt(rhs));
end;
class operator TObjectRec.Implicit(obj: TObject): TObjectRec;
begin
Result.Value := obj;
end;
class operator TObjectRec.Implicit(rec: TObjectRec): TObject;
begin
Exit(rec.Value);
end;
begin
end.
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