Delphi 设计模式：《HeadFirst设计模式》Delphi7代码

模板方法模式定义了一个算法骨架，允许子类对算法的某个或某些步骤进行重写（override)。
1.CoffeineBeverageWithHook
{《HeadFirst设计模式》之模板方法模式 }
{ 编译工具: Delphi7.0 }
{ E-Mail : xshlife@163.com }

unit uCoffeineBeverageWithHook;

interface

uses
SysUtils;

type
TCoffeineBeverageWithHook = class(TObject)
protected
procedure BoilWater;
procedure Brew; virtual; abstract;
procedure PourInCup;
procedure AddCondiments; virtual; abstract;
function CustomerWantsCondiments: Boolean; virtual; { 钩子 }
public
procedure PrepareRecipe; { 模板方法 }
end;

TCoffeeWithHook = class(TCoffeineBeverageWithHook)
private
function GetUserInput: string;
public
procedure Brew; override;
procedure AddCondiments; override;
function CustomerWantsCondiments: Boolean; override;
end;

TTeaWithHook = class(TCoffeineBeverageWithHook)
private
function GetUserInput: string;
public
procedure Brew; override;
procedure AddCondiments; override;
function CustomerWantsCondiments: Boolean; override;
end;

implementation

{ TCoffeineBeverageWithHook }

procedure TCoffeineBeverageWithHook.BoilWater;
begin
Writeln('Boiling Water');
end;

function TCoffeineBeverageWithHook.CustomerWantsCondiments: Boolean;
begin
Result := True;
end;

procedure TCoffeineBeverageWithHook.PourInCup;
begin
Writeln('Poiling into cup');
end;

procedure TCoffeineBeverageWithHook.PrepareRecipe;
begin
BoilWater;
Brew;
PourInCup;
if CustomerWantsCondiments then
AddCondiments;
end;

{ TCoffeeWithHook }

procedure TCoffeeWithHook.AddCondiments;
begin
Writeln('Add Sugar and Milk');
end;

procedure TCoffeeWithHook.Brew;
begin
Writeln('Drip Coffee Through Filter');
end;

function TCoffeeWithHook.CustomerWantsCondiments: Boolean;
var
Answer: string;