__isset（）对象自己的魔术函数

Question

I know you can do this

class Object
{
    private $ar;

    public function __isset($name)
    {
        return isset($this->ar[$name]);
    }
}

which can then be used to do the following

$obj = new Object();
if (isset($obj->name)) { /* ... */ }

However is there a way to do this

$obj = new Object();
if (isset($obj)) { /* .... */ }

Where i can control the return of $obj status using the __isset() magic method on the object it self.

Answer 1

You could only define a new global function myIsset() or something like it to do this.

function myIsset($obj = NULL)
{
    ...
}

When checking the variable $obj with isset PHP doesn't interact with the object that might be referenced by the variable at all.