Add IndividualTimer example

Author: Greg Bowler

example/01-delay-1-5-10-seconds.php

@@ -0,0 +1,27 @@
+<?php
+/**
+ * This example shows how an IndividualTimer can be used to schedule some ticks
+ * in the future. Here, the callback function simply calculates how many seconds
+ * have passed since the script's start and echos. You can see the correlation
+ * with the output to the three trigger times that are added after creating
+ * the IndividualTimer object.
+ */
+require("../vendor/autoload.php");
+
+$timeAtScriptStart = microtime(true);
+
+$timer = new \Gt\Async\Timer\IndividualTimer();
+$timer->addTriggerTime($timeAtScriptStart + 1);
+$timer->addTriggerTime($timeAtScriptStart + 5);
+$timer->addTriggerTime($timeAtScriptStart + 10);
+
+$timer->addCallback(function() use($timeAtScriptStart) {
+	$now = microtime(true);
+	$secondsPassed = round($now - $timeAtScriptStart);
+	echo "Number of seconds passed: $secondsPassed", PHP_EOL;
+});
+
+$loop = new \Gt\Async\Loop();
+$loop->addTimer($timer);
+echo "Starting...", PHP_EOL;
+$loop->run();

src/Timer/IndividualTimer.php

@@ -2,9 +2,12 @@
 namespace Gt\Async\Timer;
 
 class IndividualTimer extends Timer {
-	public function __construct(float $triggerTime) {
+	public function __construct(float $triggerTime = null) {
 		parent::__construct();
-		$this->addTriggerTime($triggerTime);
+
+		if(!is_null($triggerTime)) {
+			$this->addTriggerTime($triggerTime);
+		}
 	}
 
 	public function addTriggerTime(float $triggerTime):void {