InterfaceFactory - Manage a list is generic NoRef counted interfaces.

InterfaceFactory.pas

(*******************************************************************************

InterfaceFactory - Manage a list is generic NoRef counted interfaces.

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-------------------------------------------------------------------------------
Release 1.0.stable:
  Initial Release

-------------------------------------------------------------------------------
Usage:

type
  IMyInterface = interface(IBaseInterface)
    ['{2A52D6A4-F436-40E7-B12E-F3DE36D2D0A0}']
    procedure Test;
  end;

  TMyInterface = class(TBaseInterface, IMyInterface)
  public
    procedure Test;
  end;

var
  F: TInterfaceFactory;
  I: IMyInterface;
begin
  F := TInterfaceFactory.Create;
  F.RegisterInterface(IMyInterface, TMyInterface);
  F.GetInterface(IMyInterface, I);
  I.Test;
  F.ReleaseInterface(I);
  FreeAndNil(F);
end.

*******************************************************************************)


unit InterfaceFactory;

interface

uses
  System.SysUtils,
  System.Generics.Collections;

type

  { IBaseInterface }
  IBaseInterface = interface
    ['{29D01AA3-E370-4EB0-B258-FB9D17BB090A}']
  end;

  { TBaseInterface }
  TBaseInterface = class(TNoRefCountObject, IBaseInterface)
  public
    constructor Create; virtual;
    destructor Destroy; override;
  end;

  { TBaseInterfaceClass }
  TBaseInterfaceClass = class of TBaseInterface;

  { TInterfaceFactory }
  TInterfaceFactory = class(TObject)
  protected
    FList: TDictionary<TGUID, TBaseInterfaceClass>;
  public
    constructor Create;
    destructor Destroy; override;
    function RegisterInterface(const aGUID: TGUID; const aClass: TBaseInterfaceClass): Boolean;
    function GetInterface(const aGUID: TGUID; const [ref] aInterface: IBaseInterface): Boolean;
    function ReleaseInterface(const [ref] aInterface: IBaseInterface): Boolean;
  end;

implementation

{ TBaseInterface }
constructor TBaseInterface.Create;
begin
  inherited;
end;

destructor TBaseInterface.Destroy;
begin
  inherited;
end;

{ TInterfaceFactory }
constructor TInterfaceFactory.Create;
begin
  FList := TDictionary<TGUID, TBaseInterfaceClass>.Create;
end;

destructor TInterfaceFactory.Destroy;
begin
  FreeAndNil(FList);
  inherited;
end;

function TInterfaceFactory.RegisterInterface(const aGUID: TGUID; const aClass: TBaseInterfaceClass): Boolean;
begin
  if Supports(aClass, aGUID) then
    Result := FList.TryAdd(aGUID, aClass)
  else
    Result := False;
end;

function TInterfaceFactory.GetInterface(const aGUID: TGUID; const [ref] aInterface: IBaseInterface): Boolean;
var
  LClass: TBaseInterfaceClass;
begin
  Result := False;
  if FList.TryGetValue(aGUID, LClass) then
    Result := Supports(LClass.Create, aGUID, IBaseInterface(Pointer(@aInterface)^));

  if not Result then
    IBaseInterface(Pointer(@aInterface)^) := nil;
end;

function TInterfaceFactory.ReleaseInterface(const [ref] aInterface: IBaseInterface): Boolean;
var
  Temp: TBaseInterface;
begin
  Result := False;
  if aInterface = nil then Exit;
  Temp := TBaseInterface(aInterface);
  IBaseInterface(Pointer(@aInterface)^) := nil;
  Temp.Free;
  Result := True;
end;

end.