Tickers in Pascal

program Tickers;

uses
  SysUtils, DateUtils;

var
  ticker: TTimer;
  done: Boolean;

procedure TimerEvent(Sender: TObject);
begin
  WriteLn('Tick at ', DateTimeToStr(Now));
end;

begin
  done := False;
  
  // Create a timer that fires every 500 milliseconds
  ticker := TTimer.Create(nil);
  ticker.Interval := 500;
  ticker.OnTimer := @TimerEvent;
  ticker.Enabled := True;

  // Run the timer for 1600 milliseconds
  Sleep(1600);

  // Stop the timer
  ticker.Enabled := False;
  ticker.Free;

  WriteLn('Ticker stopped');
end.

Tickers in Pascal can be implemented using the TTimer class, which is similar to the concept of tickers in other languages. Here’s an example of a ticker that ticks periodically until we stop it.

The TTimer class is used to create a timer that fires an event every 500 milliseconds. We set up an event handler TimerEvent that prints the current time when the timer fires.

In the main program:

1. We create a TTimer object and set its interval to 500 milliseconds.
2. We assign our TimerEvent procedure to the OnTimer event of the timer.
3. We enable the timer by setting Enabled to True.
4. We let the program run for 1600 milliseconds using the Sleep function.
5. After 1600 milliseconds, we stop the timer by setting Enabled to False and free the timer object.

When we run this program, the ticker should tick 3 times before we stop it.

$ fpc tickers.pas
$ ./tickers
Tick at 2023-06-01 15:30:00
Tick at 2023-06-01 15:30:00
Tick at 2023-06-01 15:30:01
Ticker stopped

Note that Pascal’s TTimer is not as precise as timers in some other languages, so the exact timing of the ticks may vary slightly.