1--TEST-- 2ZE2 singleton 3--FILE-- 4<?php 5 6class Counter { 7 private $counter = 0; 8 9 function increment_and_print() { 10 echo ++$this->counter; 11 echo "\n"; 12 } 13} 14 15 16class SingletonCounter { 17 private static $m_instance = NULL; 18 19 static function Instance() { 20 if (self::$m_instance == NULL) { 21 self::$m_instance = new Counter(); 22 } 23 return self::$m_instance; 24 } 25} 26 27SingletonCounter::Instance()->increment_and_print(); 28SingletonCounter::Instance()->increment_and_print(); 29SingletonCounter::Instance()->increment_and_print(); 30 31?> 32--EXPECT-- 331 342 353 36