polymorphism question

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polymorphism question

Darius Blaszyk
I would like to declare a polymorph class. The class has several properties and it's the read and write specifiers that I want to be virtual abstract. So derived classes override the read and write specifiers. The problem however is that I get an EAbstractError. The property is still considered to be abstract according to the compiler. So what did I wrong? I have added an example below.
Is it perhaps not allowed to use this construct? What would then be the best way?
Darius
 
<<example>>
 
unit MyTest;
 
{$mode objfpc}{$H+}
 
interface
 
uses
  Classes, ComCtrls, SysUtils;
 
type
  TCustomClass = class
  private
    //virtual mehods
    function GetMyProperty: string; virtual; abstract;
    procedure SetMyProperty(Value: string); virtual; abstract;
  published
 
    property MyProperty: string Read GetMyProperty Write SetMyProperty;
  end;
 
  TMyClass = class(TCustomClass)
  private
    FMyProperty: string;
    function GetMyProperty: string; overload;
    procedure SetMyProperty(Value: string); overload;
  published
    property MyProperty;
  end;
 
implementation
 
function TMyClass .GetMyProperty: string;
begin
  Result := FMyProperty;
end;
 
procedure TMyClass .SetMyProperty(Value: string);
begin
  if Value = FMyProperty then
    exit;
    
  FMyProperty := Value;
end;
end.
 
 

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