[fpc-pascal] Help with TList example

[James Richters]

Thank you for the help, I'll give it a try!

James

-----Original Message-----
From: fpc-pascal <fpc-pascal-bounces at lists.freepascal.org> On Behalf Of Jean SUZINEAU via fpc-pascal
Sent: Tuesday, September 8, 2020 8:47 AM
To: fpc-pascal at lists.freepascal.org
Cc: Jean SUZINEAU <Jean.Suzineau at wanadoo.fr>
Subject: Re: [fpc-pascal] Help with TList example

Another way is to declare TMyRec as class instead of record.

In this case, you don't need the  dereference operator ^ .

No need of new and dispose, just Create and Free, as for TMyRecList.

I don't know if there is a better performance when you use a record, but as far as I know, record/object/new/dispose is just the old syntax for the first object oriented programming born with Turbo Pascal 5.5 around 1989.

The new syntax with class / constructor Create / destructor Free is born Delphi 1 around 1995.

Below is your code modified with TMyRec=class

==========================

program Project1;
{$mode objfpc}{$H+}

uses
   SysUtils, Classes;

type
   TMyRec=class
     Value: Integer;
     AByte: Byte;
   end;

   TMyRecList=class(TList)
   private
     function Get(Index: Integer): TMyRec;
   public
     destructor Destroy; override;
     function Add(Value: TMyRec): Integer;
     property Items[Index: Integer]: TMyRec read Get; default;
   end;

{ TMyRecList }

function TMyRecList.Add(Value: TMyRec): Integer; begin
   Result := inherited Add(Value);
end;

destructor TMyRecList.Destroy;
var
   i: Integer;
begin
   for i := 0 to Count - 1 do
     Items[i].Free;
   inherited;
end;

function TMyRecList.Get(Index: Integer): TMyRec; begin
   Result := TMyRec(inherited Get(Index)); end;

var
   MyRecList: TMyRecList;
   MyRec: TMyRec;
   tmp: Integer;
begin
   MyRecList := TMyRecList.Create;
   for tmp := 0 to 9 do
   begin
     MyRec:= TMyRec.Create;
     MyRec.Value := tmp;
     MyRec.AByte := Byte(tmp);
     MyRecList.Add(MyRec);
   end;

   for tmp := 0 to MyRecList.Count - 1 do
     Writeln('Value: ', MyRecList[tmp].Value, ' AByte: ', MyRecList[tmp].AByte);
   WriteLn('  Press Enter to free the list');
   ReadLn;
   MyRecList.Free;
end.

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