继承类的构造和析构方法

1type
2 TPerson = class//(Tobject) //默认是继承 Tobject的
3 private
4 { Private declarations }
5 public
6 Name: String;
7 Tall: Integer;
8 Age: Integer;
9 WaistLine: integer;
10
11 { Public declarations }
12 end;
13procedure TForm1.Button1Click(Sender: TObject);
14VAR
15 APerson: Tperson;
16begin
17 APerson := Tperson.Create; //必须用继承 TObject的构造方法
18 APerson.Name := '涂磊';
19 APerson.Tall := 159; IntToStr(APerson.Tall);
20 APerson.Age := 21;
21 APerson.WaistLine := 25;
22 ShowMessage(APerson.Name + #13#10 + '身高= ' + IntToStr(APerson.Tall) + #13#10 + '年龄= ' + IntToStr(APerson.Age)
23 + #13#10 + '腰围= ' + IntToStr(APerson.WaistLine));
24 APerson.Free; //必须用 TObject的析构方法 比Aperson.Destroy要好,因为Free 彻底清除了该对象Aperson,而Destroy只是把与对象
25 //属性的 链接删除,并没有清除Aperson的对象实体
26end;
27
28procedure TForm1.Button2Click(Sender: TObject);
29VAR
30 AHuman: THuman;
31begin
32 //AHuman := THuman.Create; //没有继承 TObject的构造方法,也不能用该方法
33 AHuman.Name := '涂磊';
34 AHuman.Tall := 159; IntToStr(AHuman.Tall);
35 AHuman.Age := 21;
36 AHuman.WaistLine := 25;
37 ShowMessage(AHuman.Name + #13#10 + '身高= ' + IntToStr(AHuman.Tall) + #13#10 + '年龄= ' + IntToStr(AHuman.Age)
38 + #13#10 + '腰围= ' + IntToStr(AHuman.WaistLine));
39 // AHuman.Free; //也不能用该TObject的析构方法
40end;
41
42
字段(Field)与对象引用(object reference)的实现

1type
2 THand = class(TObject)
3 public
4 Length: integer;
5 Thick: integer;
6 Color: Tcolor;
7 { Public declarations }
8 end;
9type
10 TFoot = Object
11 public
12 Length: integer;
13 Thick: integer;
14 Color: Tcolor;
15 { Public declarations }
16 end;
17type
18 TPerson = class(TObject)
19 public
20 LHand: THand; //Object reference ,Class的类
21 LFoot: TFoot; //Object Instance ,Object的类
22 LTall: integer; //一般字段
23 { Public declarations }
24 end;
25
26type
27 TForm1 = class(TForm)
28 Button1: TButton;
29 Label1: TLabel;
30 Label2: TLabel;
31 procedure Button1Click(Sender: TObject);
32 private
33 { Private declarations }
34 public
35 { Public declarations }
36 end;
37procedure TForm1.Button1Click(Sender: TObject);
38VAR
39 tulater: TPerson;
40begin
41 tulater := TPerson.Create;
42 tulater.LTall := 180;
43
44 tulater.LHand := THand.Create; //对象引用(Object reference )
45 tulater.LHand.Length := 100;
46 tulater.LHand.Thick := 6;
47 tulater.LHand.Color := clYellow;
48
49 tulater.LFoot.Length := 130;
50 tulater.LFoot.Thick := 8;
51 tulater.LFoot.Color := clBlue;
52 label1.Color := tulater.LHand.Color;
53 label2.Color := tulater.LFoot.Color;
54 ShowMessage(
55 ' tulater ' + #13 +
56 ' 身高 = ' + IntToStr(tulater.LTall) + #13 +
57 ' 手长 = ' + IntToStr(tulater.LHand.Length) + #13 +
58 ' 手粗 = ' + IntToStr(tulater.LHand.Thick) + #13 +
59 ' 脚长 = ' + IntToStr(tulater.LFoot.Length) + #13 +
60 ' 脚粗 = ' + IntToStr(tulater.LFoot.Color) + #13
61 );
62 tulater.LHand.Free; //对象解除引用
63 tulater.Free;
64end;
65
66