delphi 函数过程类型委托...？

算是一种减少单元之间的引用的方法

类似委托

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 1 unit Unit5;
 2 
 3 interface
 4 
 5 uses System.Classes, System.SysUtils, Vcl.Dialogs;
 6 
 7 type
 8   // 声明过程类型
 9   TObjFuns = procedure(const str1, str2: string) of object;
10 
11   IFormattedNumber = interface
12     ['{19AE4E57-A022-45B1-AA42-43FF5142D685}']
13     function FormattedString: string;
14     function GetName: string;
15   end;
16 
17   TFormattedInteger = class(TInterfacedObject, IFormattedNumber)
18   private
19     FValue: Integer;
20   public
21     // 声明过程变量
22     FPro: TObjFuns;
23     constructor Create(AValue: Integer);
24     destructor Destroy; override;
25     function FormattedString: string;
26     function GetName: string;
27     procedure DoDelegate(str1, str2: string);
28   end;
29 
30   TFormattedHexInteger = class(TFormattedInteger, IFormattedNumber)
31     destructor Destroy; override;
32     function FormattedString: string;
33     function GetName: string;
34   end;
35 
36 implementation
37 
38 { TFormattedInteger }
39 
40 constructor TFormattedInteger.Create(AValue: Integer);
41 begin
42   inherited Create;
43   DoDelegate('TFormattedInteger', 'Destroy');
44   FValue := AValue;
45 end;
46 
47 destructor TFormattedInteger.Destroy;
48 begin
49   DoDelegate('TFormattedInteger', 'Destroy');
50   inherited Destroy;
51 end;
52 
53 procedure TFormattedInteger.DoDelegate(str1, str2: string);
54 begin
55   // 使用过程变量
56   if Assigned(FPro) then
57     FPro(str1, str2);
58 end;
59 
60 function TFormattedInteger.FormattedString: string;
61 begin
62   Result := 'This integer is' + IntToStr(FValue);
63 end;
64 
65 function TFormattedInteger.GetName: string;
66 begin
67   Result := 'TFormattedInteger.GetName';
68 end;
69 
70 { TFormattedHexInteger }
71 
72 destructor TFormattedHexInteger.Destroy;
73 begin
74   DoDelegate('TFormattedHexInteger', 'Destroy');
75   inherited Destroy;
76 end;
77 
78 function TFormattedHexInteger.FormattedString: string;
79 begin
80   Result := 'The hex integer is $' + IntToHex(FValue, 4);
81 end;
82 
83 function TFormattedHexInteger.GetName: string;
84 begin
85   Result := 'TFormattedHexInteger.GetName';
86 end;
87 
88 end.

View Code

 1 unit Unit4;
 2 
 3 interface
 4 
 5 uses
 6   Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants,
 7   System.Classes, Vcl.Graphics,
 8   Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls,
 9   Unit5;
10 
11 type
12   TForm4 = class(TForm)
13     btn1: TButton;
14     mmo1: TMemo;
15     procedure btn1Click(Sender: TObject);
16   private
17     procedure PrintfStr(const str1, str2: string);
18     { Private declarations }
19   public
20     { Public declarations }
21   end;
22 
23 var
24   Form4: TForm4;
25 
26 implementation
27 
28 {$R *.dfm}
29 
30 procedure TForm4.btn1Click(Sender: TObject);
31 var
32   MyInt: TFormattedInteger;
33 begin
34   MyInt := TFormattedInteger.Create(123);
35   // 给过程变量赋值
36   MyInt.FPro := PrintfStr;
37   mmo1.Lines.Add(MyInt.FormattedString);
38   MyInt.Free;
39   mmo1.Lines.Add('End of Procedure  ' + #13);
40 
41 end;
42 
43 procedure TForm4.PrintfStr(const str1, str2: string);
44 begin
45   mmo1.Lines.Add(str1 + '->' + str2);
46 end;
47 
48 end.

ps:最近学习接口，接口代码来自:delphi COM深入编程p22

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