如何在函数中引用全局实例化的PHP对象？

Previously, I had a global array ($v) and referenced it from within functions by using global $v;. I now want to encapsulate everything about that array, so I wrote a class. In the global context, I instantiate the class:

$vi = new my_v();

Within a function I want to call a method of that object:

function f($x) {
  $vi->add($x);
}

How do I refer to $vi within the function?

Use the global keyword:

function f($x) {
  global $vi;
  $vi->add($x);
}

You can also use the $GLOBALS superglobal array:

function f($x) {
  $GLOBALS['vi']->add($x);
}

See: http://us1.php.net/manual/en/language.variables.scope.php

Working example: http://3v4l.org/ERIK8