Про generic'и, "примеси", интерфейсы и енумераторы. Только код

Интерфейс:

 ImsDiagramm = interface(ImsObjectWrap)
 ['{59F2D068-F06F-4378-9ED4-888DFE8DFAF2}']
  function Get_Name: String;
  procedure Invalidate;
  procedure ProcessClick(const aStart: TPointF);
  procedure Clear;
  procedure SelectShape(aList: TStrings; anIndex: Integer);
  procedure AllowedShapesToList(aList: TStrings);
  function CurrentShapeClassIndex: Integer;
  procedure DrawTo(const aCanvas: TCanvas);
  property Name: String
   read Get_Name;
 end;//ImsDiagramm

 TmsDiagrammsEnumerator = TEnumerator<ImsDiagramm>;

 ImsDiagramms = interface(ImsObjectWrap)
 ['{819BEEBA-97BB-48F1-906E-107E67706D19}']
  procedure AllowedShapesToList(aList: TStrings);
  function CurrentShapeClassIndex: Integer;
  function CurrentDiagrammIndex: Integer;
  function pm_GetCurrentDiagramm: ImsDiagramm;
  procedure AddDiagramm(aList: TStrings);
  procedure Serialize;
  procedure DeSerialize;
  procedure Clear;
  procedure SelectDiagramm(anIndex: Integer);
  procedure SelectShape(aList: TStrings; anIndex: Integer);
  procedure ProcessClick(const aStart: TPointF);
  function GetEnumerator: TmsDiagrammsEnumerator;
  property CurrentDiagramm: ImsDiagramm
   read pm_GetCurrentDiagramm;
 end;//ImsDiagramms

Обращаем внимание на function GetEnumerator: TmsDiagrammsEnumerator.

Теперь примесь:

{$IfNDef TmsItemsHolder_uses_intf}
// Объект содержащий список других объектов

// interface

{$Define TmsItemsHolder_uses_intf}

// uses
 Generics.Collections,
 Data.DBXJSONReflect,
 System.Rtti

{$Else TmsItemsHolder_uses_intf}

{$IfNDef TmsItemsHolder_intf}
// http://programmingmindstream.blogspot.ru/2014/12/generic-2.html

{$Define TmsItemsHolder_intf}

 TmsRttiFieldLambda = reference to procedure (aField: TRttiField);

 TmsItemsList = TList<TmsItem>;
 TmsItemsListEnumerator = TEnumerator<TmsItem>;

 TmsItemsHolder = class(TmsItemsHolderParent)
 private
  [JSONMarshalled(True)]
  f_Items : TmsItemsList;
  function pm_GetItems: TmsItemsList;
  procedure pm_SetItems(aValue: TmsItemsList);
  class procedure RegisterItemsLike(aLambda: TmsRttiFieldLambda);
 public
  constructor Create;
  destructor Destroy; override;
  property Items: TmsItemsList read pm_GetItems write pm_SetItems;
  procedure Assign(anOther : TmsItemsHolder);
  class procedure RegisterInMarshal(aMarshal: TJSONMarshal);
  class procedure RegisterInUnMarshal(aMarshal: TJSONUnMarshal);
  function GetEnumerator: TmsItemsListEnumerator;
 end;//TmsItemsHolder

{$Else TmsItemsHolder_intf}

// implementation

{$IfNDef TmsItemsHolder_uses_impl}

// uses
  System.TypInfo

{$Define TmsItemsHolder_uses_impl}

{$Else TmsItemsHolder_uses_impl}

// TmsItemsHolder

constructor TmsItemsHolder.Create;
begin
 inherited;
 Assert(f_Items = nil);
 f_Items := TmsItemsList.Create;
end;

destructor TmsItemsHolder.Destroy;
begin
 FreeAndNil(f_Items);
 inherited;
end;

function TmsItemsHolder.pm_GetItems: TmsItemsList;
begin
 if (f_Items = nil) then
  f_Items := TmsItemsList.Create;
 Result := f_Items;
end;

procedure TmsItemsHolder.pm_SetItems(aValue: TmsItemsList);
var
 l_Item : TmsItem;
begin
 if (f_Items <> nil) then
  f_Items.Clear;
 if (aValue <> nil) then
  for l_Item in aValue do
  begin
   if (f_Items = nil) then
    f_Items := TmsItemsList.Create;
   f_Items.Add(l_Item);
  end;//for l_Shape in aValue
end;

procedure TmsItemsHolder.Assign(anOther : TmsItemsHolder);
begin
 Self.Items := anOther.Items;
end;

class procedure TmsItemsHolder.RegisterItemsLike(aLambda: TmsRttiFieldLambda);
var
 l_Field : TRttiField;
begin
 for l_Field in TRttiContext.Create.GetType(Self).GetFields do
  if (l_Field.Visibility = mvPrivate) then
   if (l_Field.Name = 'f_Items') then
   begin
    aLambda(l_Field);
    Exit;
   end;//l_Field.Name = 'f_Items'
 Assert(false, 'Не найдено поля для Items');
end;

class procedure TmsItemsHolder.RegisterInMarshal(aMarshal: TJSONMarshal);
begin
 RegisterItemsLike(
  procedure (aField: TRttiField)
  var
   l_FieldName : String;
  begin
   l_FieldName := aField.Name;
   aMarshal.RegisterConverter(Self, l_FieldName,
    function (Data: TObject; Field: String): TListOfObjects
    var
     l_Item: TmsItem;
     l_Index: Integer;
    begin
     Assert(Field = l_FieldName);
     SetLength(Result, (Data As TmsItemsHolder).Items.Count);
     l_Index := 0;
     for l_Item in (Data As TmsItemsHolder).Items do
     begin
      Result[l_Index] := l_Item.toObject;
      Inc(l_Index);
     end;//for l_Item
    end
   );//aMarshal.RegisterConverter
  end
 );//RegisterItemsLike
 aMarshal.RegisterJSONMarshalled(Self, 'FRefCount', false);
end;

class procedure TmsItemsHolder.RegisterInUnMarshal(aMarshal: TJSONUnMarshal);
begin
 RegisterItemsLike(
  procedure (aField: TRttiField)
  var
   l_FieldName : String;
  begin
   l_FieldName := aField.Name;
   aMarshal.RegisterReverter(Self, l_FieldName,
    procedure (Data: TObject; Field: String; Args: TListOfObjects)
    var
     l_Object: TObject;
     l_Holder : TmsItemsHolder;
     l_ItemI : TmsItem;
    begin
     Assert(Field = l_FieldName);
     l_Holder := Data As TmsItemsHolder;
     Assert(l_Holder <> nil);

     for l_Object in Args do
     begin
      if Supports(l_Object, TmsItem, l_ItemI) then
       l_Holder.Items.Add(l_ItemI)
      else
       raise Exception.Create(l_Object.ClassName + ' не поддерживает нужный интерфейс');
     end//for l_Object
    end
   );//aMarshal.RegisterReverter
  end
 );//RegisterItemsLike
end;

function TmsItemsHolder.GetEnumerator: TmsItemsListEnumerator;
begin
 Result := f_Items.GetEnumerator;
end;

{$EndIf TmsItemsHolder_uses_impl}

{$EndIf TmsItemsHolder_intf}
{$EndIf TmsItemsHolder_uses_intf}

Обращаем внимание на:

 TmsItemsListEnumerator = TEnumerator<TmsItem>
и
 function GetEnumerator: TmsItemsListEnumerator.

Теперь реализация:

unit msCustomDiagramms;

interface

uses
 {$Include msItemsHolder.mixin.pas}
 ,
 msShape,
 msDiagramm,
 msInterfaces,
 msDiagrammsPrim
;

type
 TmsItemsHolderParent = TmsDiagrammsPrim;
 TmsItem = ImsDiagramm;
 {$Include msItemsHolder.mixin.pas}
 TmsCustomDiagramms = class abstract(TmsItemsHolder, ImsDiagramms)
 end;//TmsCustomDiagramms

implementation

uses
 {$Include msItemsHolder.mixin.pas}
 ,
 System.SysUtils
 ;

{$Include msItemsHolder.mixin.pas}

end.

Ссылки:

https://bitbucket.org/ingword/mindstream/src/39ba55201bbe26fff14e321a7e216ab018bf6b22/msInterfaces.pas?at=MS-7_Lulin_Upgrade

https://bitbucket.org/ingword/mindstream/src/39ba55201bbe26fff14e321a7e216ab018bf6b22/msItemsHolder.mixin.pas?at=MS-7_Lulin_Upgrade

https://bitbucket.org/ingword/mindstream/src/39ba55201bbe26fff14e321a7e216ab018bf6b22/msCustomDiagramms.pas?at=MS-7_Lulin_Upgrade