Template 模式之Delphi实现

unit Tpl_meth;

{Design pattern example -some simple classes using the Template Method pattern.}interface

type  TAbstractTemplateClass = class(TObject)  protected    function Algorithm_StepA: Integer; virtual; abstract;    function Algorithm_StepB: Integer; virtual; abstract;    function Algorithm_StepC: Integer; virtual; abstract;  public    function Algorithm: Integer;  end;

  TConcreteClassA = class(TAbstractTemplateClass)  protected    function Algorithm_StepA: Integer; override;    function Algorithm_StepB: Integer; override;    function Algorithm_StepC: Integer; override;  end;

  TConcreteClassB = class(TAbstractTemplateClass)  protected    function Algorithm_StepA: Integer; override;    function Algorithm_StepB: Integer; override;    function Algorithm_StepC: Integer; override;  end;

implementation

function TAbstractTemplateClass.Algorithm: Integer;begin  Result := Algorithm_StepA +            Algorithm_StepB +            Algorithm_StepC;end;

function TConcreteClassA.Algorithm_StepA: Integer;begin  Result := 1;end;

function TConcreteClassA.Algorithm_StepB: Integer;begin  Result := 2;end;

function TConcreteClassA.Algorithm_StepC: Integer;begin  Result := 3;end;

function TConcreteClassB.Algorithm_StepA: Integer;begin  Result := 4;end;

function TConcreteClassB.Algorithm_StepB: Integer;begin  Result := 5;end;

function TConcreteClassB.Algorithm_StepC: Integer;begin  Result := 6;end;

end.

 

/

 

unit Unit1;

interface

uses  SysUtils, WinTypes, WinProcs, Messages, Classes, Graphics, Controls,  Forms, Dialogs, StdCtrls;

type  TForm1 = class(TForm)    Button1: TButton;    Button2: TButton;    procedure Button1Click(Sender: TObject);    procedure Button2Click(Sender: TObject);  private    { Private declarations }  public    { Public declarations }  end;

var  Form1: TForm1;

implementation

{$R *.DFM}

uses tpl_meth;

procedure TForm1.Button1Click(Sender: TObject);var  AnAbstractObject: TAbstractTemplateClass;begin  AnAbstractObject := TConcreteClassA.Create;  try    ShowMessage('Algorithm Result = ' + Inttostr(AnAbstractObject.Algorithm));  finally    AnAbstractObject.Destroy;  end;end;

procedure TForm1.Button2Click(Sender: TObject);var  AnAbstractObject: TAbstractTemplateClass;begin  AnAbstractObject := TConcreteClassB.Create;  try    ShowMessage('Algorithm Result = ' + Inttostr(AnAbstractObject.Algorithm));  finally    AnAbstractObject.Destroy;  end;end;

end.