对delphi的Create,inherited,AfterConstruction的流程了解及测试

写了一个测试代码, 创建一个窗体拉上一个按钮控件,复制以下的代码

1. unit Unit1;
3. interface
5. uses
6.   Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
7.   Dialogs, StdCtrls;
9. type
10.   TForm1 = class(TForm)
11.     Button1: TButton;
12.     procedure Button1Click(Sender: TObject);
13.   private
14.     { Private declarations }
15.   public
16.     { Public declarations }
17.   end;
18.   C1 = class //(TPersistent)
19.   private
20.     p1:string;
21.   public
22.     procedure Show;
23.     procedure AfterConstruction; override;
24.     procedure BeforeDestruction; override;
25.     constructor Create; virtual;
26.     procedure test(str: string);
27.   end;
28.   C2 = class(C1)
29.   public
30.     constructor Create; override;
31.     constructor CreateNew; virtual;
32.     procedure AfterConstruction; override;
33.     procedure Show;
34.   end;
35.   C3 = class(c2)
36.   end;
38. var
39.   Form1: TForm1;
40. implementation
41. {$R *.dfm}
42. { C1 }
44. procedure C1.AfterConstruction;
45. begin
46.   inherited AfterConstruction;
47.   test('C1.AfterConstruction'); ;
48. end;
50. procedure C1.BeforeDestruction;
51. begin
52.   test('C1.BeforeDestruction'); ;
53.   inherited BeforeDestruction;
54. end;
56. constructor C1.Create;
57. begin
58. inherited;
59.   test('C1.Create');
60. end;
62. procedure C1.Show;
63. begin
64.   ShowMessage(p1);
65. end;
67. procedure C1.test(str: string);
68. begin
69.   ShowMessage(str);
70. end;
72. { C2 }
74. procedure C2.AfterConstruction;
75. begin
76.   inherited;
77.   ShowMessage('C2.AfterConstruction');
78. end;
80. constructor C2.Create;
81. begin
82.   inherited Create;
83.   test('c2.Create'); ;
84. end;
86. constructor C2.CreateNew;
87. begin
88.   Create;
89.   test('c2.CreateNew');
90. end;
92. procedure C2.Show;
93. begin
94.   inherited Show;
95.   test('c2.show');
96. end;
98. procedure TForm1.Button1Click(Sender: TObject);
99. var
100.   a: c3;
101.   b: c2;
102.   c:c1;
103.   begin
104.   c:=c3.CreateNew;
105.   c.p1:='aaa';
106.   c.Show;
107.   c.test('aaaaa');
108. end;
110. end.

单击按钮时,依次显示:

C1.Create    // 运行了c:=c3.CreateNew; inherited Create;

C2.Create    //Create;

C2.CreateNew

C1.AfterConstruction    C2.AfterConstruction 里的inherited 

C2.AfterConstruction

aaa

aaaaa

 

在对象创建前会自动调用AfterConstruction,资料参考空间里之前发布的文章