//猪八戒类
class Pig{
public function display(){
echo '猪八戒下凡，哼哼坠地! <br/>';
}
}
//main
//打开蓝灯
$light = new Light();
$blueglass = new BlueGlass();
$light->TrunOn($blueglass);
//打开绿灯
$greenglass = new GreenGlass();
$light->TrunOn($greenglass);
//坏了猪八戒从手电筒里面出生了, 现在做了类型限制
$pig = new Pig();
$light->TrunOn($pig); //Catchable fatal error: Argument 1 passed to Light::TrunOn() must be an instance of BlueGlass
/****
如果按PHP本身特点,不检测类型,
本身就可以说是多态的,甚至变态的.
//猪八戒类
class Pig{
public function display(){
echo '猪八戒下凡，哼哼坠地! <br/>';
}
}
//main
//打开红灯
$light = new Light();
$redglass = new RedGlass();
$light->TrunOn($redglass);
//打开绿灯
$greenglass = new GreenGlass();
$light->TrunOn($greenglass);
//坏了猪八戒从手电筒里面出生了
$pig = new Pig();
$light->TrunOn($pig);
/*****
分析 与java那段出错程序相比
php没报错,
因为PHP是弱类型动态语言.
