Array methods
lazarus / 62-General

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riwu · 2015-12-26 09:12

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i type 
PointArr = array of TPoint;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?

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Leledumbo · 2015-12-26 09:48

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

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howardpc · 2015-12-26 10:38

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


Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
 {$ModeSwitch typehelpers}type  PointArr = array of TPoint;   
PointArrayHelper = type helper for PointArr    function Contains(x:
TPoint): Boolean;  end;    ...    function
PointArrayHelper.Contains(x: TPoint): Boolean;var  p: TPoint;begin 
Result:=False;  if (Length(Self) = 0) then    Exit  else begin    for
p in Self do      if (p.x = x.x) and (p.y = x.y) then       
Exit(True);  end;end;  var  pa: PointArray;    ...    if
pa.Contains(Point(0, 3)) then    ...