chainofresponsibilityunit3.pas

设计模式delphi版给想学delphi的朋友一个很有价值的参考

unit ChainOfResponsibilityUnit3;

interface

type

  TTopic = integer;

  THelpHandler = class
  private
    f_successor: THelpHandler;
    f_topic: TTopic;
  public
    constructor Create(h: THelpHandler = nil; t: TTopic = -1); virtual;
    function HasHelp(): boolean; virtual;
    procedure SetHandler(h: THelpHandler; t: TTopic); virtual;
    procedure HandleHelp(); virtual;
  end;

  TWidgetHelpHandler = class(THelpHandler)
  protected
    constructor Create(w: TWidgetHelpHandler; t: TTopic); virtual;
  private
    f_parent: TWidgetHelpHandler;
  end;

  TButtonHelpHandler = class(TWidgetHelpHandler)
  public
    constructor Create(d: TWidgetHelpHandler; t: TTopic);
    procedure HandleHelp();  //э糶TWidgetHelpHandler