type helpers usage - Lazarus 1.6RC1 - FPC 3.0

[frakno]

I am playing around with type helper and how they are helpful for me.

In my project I need a lot of subdivision into different actions, and depending on an action I need values for e.g. names, column widths, basic values, etc.

I give you an example how I try to use helpers to have fewer efforts. I tried to integrate Arrays into the helpers methods.

Please give me some feedback whether my approach is good and what could bring disadvantages and whether there are better ways.

Code: Pascal  [Select][+][-]

1. unit Unit1; {$mode objfpc}{$H+} {$modeswitch typehelpers}
2. interface
3.  
4. uses Classes, StdCtrls, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs;
5.  
6. type TIntegerHelper = type helper for Integer
7.        function Str: string; end;
8.  
9. type BUA = ( buaKauf, buaVkf, buaBewert, buaReal );
10.      TBuchArtHelper  = type helper for BUA
11.        function Int( AEnum : BUA ): Integer;
12.        function Str( AEnum : BUA ): String;
13.        function Val( AEnum : BUA ): Integer;
14.      end;
15.  
16. type { TForm1 } TForm1 = class( TForm)
17.     Button1 : TButton;
18.     Button2 : TButton;
19.     procedure Button1Click( Sender : TObject) ;
20.     procedure Button2Click( Sender : TObject) ;
21.   private
22.   public
23.   end;
24.  
25. var Form1 : TForm1;
26.  
27. implementation {$R *.lfm}
28.  
29. { TForm1 }
30.  
31. procedure TForm1.Button1Click( Sender : TObject) ;
32.   var
33.      intval: LongInt = 33;
34.   begin
35.     ShowMessage( intval.Str );
36.     ShowMessage( ( intval * 3).Str );
37.   end;
38.  
39. procedure TForm1.Button2Click( Sender : TObject);
40. var itest : Integer = 3;
41. begin
42.    if BUA.Int( buaReal ) = itest then begin { some Code }  end;
43.    ShowMessage(  BUA.Str( buaReal ) );
44. end;
45.  
46. { TIntegerHelper }
47.  
48.   function TIntegerHelper.Str: string;
49.   begin
50.     Result := IntToStr(Self);
51.   end;
52.  
53.   function TBuchArtHelper.Int( AEnum : BUA ): Integer;
54.   begin
55.     Result := ord( AEnum );
56.   end;
57.  
58.   function TBuchArtHelper.Str( AEnum : BUA ): String;
59.     const  description : Array[0..3] of String = ( 'Wertpapier-Kauf', 'Wertpapier-Verkauf', 'Werpapier-Bewertung', 'Wp-Real.Gewinne' );
60.   begin Result := description[ord( AEnum )]; end;
61.  
62.   function TBuchArtHelper.Val( AEnum : BUA ): Integer;
63.     const  ColumnWidth : Array[0..3] of Integer = ( 120, 120, 80, 80 );
64.   begin Result := ColumnWidth[ord( AEnum )]; end;
65.  
66. end.
67.