Array methods

[riwu]

Code: Pascal  [Select][+][-]

1. type
2.   PointArr = array of TPoint;
3. function PointArr.contains(x: TPoint): Boolean;

Is there a simple way to create routines that operates on arrays?

One way i know of is to declare PointArr as 'object', which allows type routines, but i wouldn't be able to use built-in array routines like Length(), SetLength(), [] property etc, so i would have to keep track of the length and implement these custom methods myself which makes it unnecessarily complicated, but is that the only way to achieve what i want?

[Leledumbo]

http://wiki.lazarus.freepascal.org/Helper_types

[howardpc]

Note that if you have FPC 3.0 it is now possible to write constructs like this:

Code: Pascal  [Select][+][-]

1.  
2. {$ModeSwitch typehelpers}
3. type
4.   PointArr = array of TPoint;
5.  
6.  
7.   PointArrayHelper = type helper for PointArr
8.     function Contains(x: TPoint): Boolean;
9.   end;
10.  
11.  
12.   ...
13.  
14.  
15.   function PointArrayHelper.Contains(x: TPoint): Boolean;
16. var
17.   p: TPoint;
18. begin
19.   Result:=False;
20.   if (Length(Self) = 0) then
21.     Exit
22.   else begin
23.     for p in Self do
24.       if (p.x = x.x) and (p.y = x.y) then
25.         Exit(True);
26.   end;
27. end;
28.  
29.  
30. var
31.   pa: PointArray;
32.  
33.  
34.   ...
35.  
36.  
37.   if pa.Contains(Point(0, 3)) then
38.     ...
39.                          
40.