[fpc-pascal]Interfaces, What am I doing wrong?

[memsom at interalpha.co.uk]

I knocked up the following solution.

You do not need a GUID unless you want to use COM or a COM like interface. 
Borland have actually altered Interfaces in D6 onwards so that IUnknown 
inherits from IInterface and IInterface implements nothing at all (or very 
little anyway) to help facilitate the practice of Interfaces outside of COM.

NB. didn't actually compile this so it could fail. I think the uses clause is 
complete. Moved some of your fields/methods around for better encasulation.

Matt

////////////////////////////////////////////////////////////

unit QBase;
interface

{$MODE ObjFPC}

uses
  SySutils, Classes;

type
  IQObject = interface
    procedure SetName(iName: string); //these are annoying, but are needed
    function GetName: string;

    // iirc you need the full definition
    property Name: string read GetName write SetName; 
  end;

  TQObject = class(TInterfacedObject, IQObject)
  private
    fName: string;

  protected

//interfaces don't care about scope so long as it's at least protected
//because private scop is invisible to descendents and this will break
//the interface I guess (though I've never tried this out)

    procedure SetName(iName: string); virtual; 
    function GetName: string; virtual; 


  public
    constructor Create;
    destructor Destroy; override;

    property Name: string read GetName write SetName;
  end;


//convenience routine
function NewQObjectIntf(AName: string = ''): IQObject;

implementation

function NewQObjectIntf(AName: string = ''): IQObject;
begin
  Result := TQObject.Create;

  if (AName <> '') then
    Result.Name := AName;
end;

constructor tQOTQObjectbject.Create;
begin
  fName := 'TQObject';
end;

destructor TQObject.Destroy;
begin
  inherited; // << you NEEEEED this
end;

procedure TQObject.SetName(iName: string);
begin
  Writeln('Renaming ', fName, ' to ', iName);
  fName := iName;
end;

function TQObject.GetName: string;
begin
  Result := fName;
end;

end.



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