class and object

<?php
class ColorPen {
    //彩笔颜色，默认黑色
    function __construct($color = '黑色') {
        $this->color = $color;
    }
    /**
     * 生成彩笔
     */
    public function create() {
        echo "我得到一个{$this->color}的笔\n";
    }
    /**
     * 设置彩笔颜色
     * @param $color 彩笔颜色
     */
    public function setColor($color) {
        $this->color = $color;
    }
    /**
     * 获取当前彩笔颜色
     */
    public function getColor() {
        return $this->color;
    }
}
$pen = new ColorPen();  //初始化没有提供颜色，默认黑色
$color = $pen->getColor();
echo "当前颜色：{$color} \n";
$pen->setColor("红色");
$color = $pen->getColor();
echo "设置后颜色：{$color} \n";
$penRed     = new ColorPen("红色");
$penGreen   = new ColorPen("绿色");
$penBlue    = new ColorPen("蓝色");
echo $penRed->create();
echo $penGreen->create();
echo $penBlue->create();