例子 1. 使用 get_object_vars() 
<?php class Point2D {     var $x, $y;     var $label;
      function Point2D($x, $y) {         $this->x = $x;         $this->y = $y;     }
      function setLabel($label) {         $this->label = $label;     }
      function getPoint() {         return array("x" => $this->x,                      "y" => $this->y,                      "label" => $this->label);     } }
  // "$label" is declared but not defined $p1 = new Point2D(1.233, 3.445); print_r(get_object_vars($p1));
  $p1->setLabel("point #1"); print_r(get_object_vars($p1));
  ?>
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