使用PHP中的字符串从对象获取变量

I have a Persons object. It has a variable name accessible by saying

$p = new Person('John');
echo $p->name;

Now I have a string.

$name = 'name';

I need to get $p->name using $p and $name. Something like

echo $p->[$name];

echo $p->{$name};

echo $p->$name;

echo $p->$name; may generates error if it contains special characters so following one is perfect

echo $p->{$name};