[Aristarh Dark]

Так:

Код:

unit Unit2;

interface
uses
  classes;
type
  TMyTestClass = class
    private
      FBol:boolean;
    FOnAfterChangeBol: TNotifyEvent;
    FOnBeforeChangeBol: TNotifyEvent;
    FOnBeforeReadBol: TNotifyEvent;
    FOnAfterReadBol: TNotifyEvent;
    function GetBol: boolean;
    procedure SetBol(const Value: boolean);
    procedure SetOnAfterChangeBol(const Value: TNotifyEvent);
    procedure SetOnBeforeChangeBol(const Value: TNotifyEvent);
    procedure SetOnAfterReadBol(const Value: TNotifyEvent);
    procedure SetOnBeforeReadBol(const Value: TNotifyEvent);
    public
      property Bol:boolean read GetBol write SetBol;
      property OnBeforeChangeBol:TNotifyEvent read FOnBeforeChangeBol write SetOnBeforeChangeBol; //перед изменением
      property OnAfterChangeBol:TNotifyEvent read FOnAfterChangeBol write SetOnAfterChangeBol;  //после изменения
      property OnBeforeReadBol:TNotifyEvent read FOnBeforeReadBol write SetOnBeforeReadBol;  //перед чтением
      property OnAfterReadBol:TNotifyEvent read FOnAfterReadBol write SetOnAfterReadBol;  //после чтения
  end;

implementation

{ TMyTestClass }

function TMyTestClass.GetBol: boolean;
begin
  if Assigned(FOnBeforeReadBol) then
    FOnBeforeReadBol(Self);
  Result:=FBol;
  if Assigned(FOnAfterReadBol) then
    FOnAfterReadBol(Self);
end;

procedure TMyTestClass.SetBol(const Value: boolean);
begin
  if Assigned(FOnBeforeChangeBol) then
    FOnBeforeChangeBol(Self);
  FBol:=Value;
  if Assigned(FOnAfterChangeBol) then
    FOnAfterChangeBol(Self);
end;

procedure TMyTestClass.SetOnAfterChangeBol(const Value: TNotifyEvent);
begin
  FOnAfterChangeBol := Value;
end;

procedure TMyTestClass.SetOnAfterReadBol(const Value: TNotifyEvent);
begin
  FOnAfterReadBol := Value;
end;

procedure TMyTestClass.SetOnBeforeChangeBol(const Value: TNotifyEvent);
begin
  FOnBeforeChangeBol := Value;
end;

procedure TMyTestClass.SetOnBeforeReadBol(const Value: TNotifyEvent);
begin
  FOnBeforeReadBol := Value;
end;

end.