Problem mit Constructor/Destructor

[Sir Rufo]

ich hatte das eigentlich so gedacht:

Delphi-Quellcode:

UNIT UContainer;

INTERFACE

USES
  SysUtils;

TYPE
  TContainer=Class
    Private
      FFileName:String;
    Public
      class function Build(const FName:String;AsReadOnly:Boolean) : TContainer;
      Constructor Create(const FName:String;AsReadOnly:Boolean);
      Destructor Destroy;override;
      Property FileName:String Read FFileName;
  End;

IMPLEMENTATION

class function TContainer.Build(const FName:String;AsReadOnly:Boolean) : TContainer;
begin
  if FileExists( FName ) then
    Result := TContainer.Create( FName, AsReadOnly )
  else
    Result := nil;
end;

Constructor TContainer.Create(const FName:String;AsReadOnly:Boolean);
Begin
 inherited Create;
  FFileName := FName;
  // ...
End;

Destructor TContainer.Destroy;
Begin

 inherited Destroy
End;

END.

Aufruf:

Delphi-Quellcode:

var
  Container : TContainer;
begin
  Container := TContainer.Build( 'foo.txt', False );
  if Assigned( Container ) then
  begin
    
  end;
end;