如何将对象上下文传递给匿名函数？

Question

Is there a way of passing object context to an anonymous function without passing $this as an argument?

class Foo {
    function bar() {
        $this->baz = 2;
        # Fatal error: Using $this when not in object context
        $echo_baz = function() { echo $this->baz; };
        $echo_baz();
    }
}
$f = new Foo();
$f->bar();

Answer 1

You can assign $this to some variable and then use use keyword to pass this variable to function, when defining function, though I'm not sure if it is easier to use. Anyway, here's an example:

class Foo {
    function bar() {
        $this->baz = 2;
        $obj = $this;
        $echo_baz = function() use($obj) { echo $obj->baz; };
        $echo_baz();
    }
}
$f = new Foo();
$f->bar();

It is worth noting that $obj will be seen as standard object (rather than as $this), so you won't be able to access private and protected members.