20.01.2011 22:18, Honza пишет:
2011/1/20 Alex Shishkin<alexv...@mail.ru>:
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.
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
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.
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