Author: Jonas Bilinkevicius

How can I get the following to happen with a memo: I would like to make it start 
purging lines from the top when a line is added at the bottom after I have 1024 
lines.

Answer:

You can do the following (I am making the example for TCustomMemo to make this more 
general).
1   
2   TLimitedMemo = class(TCustomMemo)
3   private
4     fChanging: Boolean;
5   protected
6     procedure Change; override;
7   public
8     constructor Create(AOwner: TComponent); override;
9   end;
10  
11  procedure TLimitedMemo.Change;
12  var
13    i: Integer;
14  begin
15    if fChanging then
16      Exit;
17    inherited;
18    with Lines do
19    try
20      BeginUpdate;
21      if Count > 5 then
22      begin
23        fChanging := True;
24        for i := 0 to Count - 6 do
25          Delete(0);
26        fChanging := False;
27      end;
28    finally
29      EndUpdate;
30    end;
31  end;
32  
33  constructor TLimitedMemo.Create(AOwner: TComponent);
34  begin
35    inherited Create(AOwner);
36    fChanging := False;
37  end;


In this case, this memo is allowing 5 lines(you can change it at your will).