我想创建一个Listener类
class Listener {
var $listeners = array();
public function add(callable $function) {
$this->listeners[] = $function;
}
public function fire() {
foreach($this->listeners as $function) {
call_user_func($function);
}
}
}
class Foo {
public function __construct($listener) {
$listener->add($this->bar);
}
public function bar() {
echo 'bar';
}
}
$listener = new Listener();
$foo = new Foo($listener);
但是此代码失败并出现此错误：
Notice: Undefined property: Foo::$bar in index.php on line 18
Catchable fatal error: Argument 1 passed to Listener::add() must be callable, null given, called in index.php on line 18 and defined index.php on line 5
我究竟做错了什么？
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