PHP: Calling a private method from within a class dying badly

问题

So this might sound a little convoluted. Fingers crossed I come across clearly.

I'm working in an MVC framework in PHP.

I load a controller /report/index which calls to a helper

<? class ReportController extends Controller { 
        public function index() {
            $foo = MainReport::get_data($_REQUEST);
        }

   }
 ?>

Inside the helper

<? class MainReport extends foo {
        public function get_data($_REQUEST) {
            // do stuff
            return $stuff_done;
        }

 }
?>

It I run it like ^this all's well and good. Unfortunately, I want to run it like this:

<? class MainReport extends foo {
        private function do_stuff() { 
            // do even better stuff here!
            return $better_stuff;
        }
        public function get_data($_REQUEST) {
            // do stuff
            $x = $this->do_stuff();    
        }

 }
?>

Unfortunately... when I try and call a private function from within a class that I've called from elsewhere... (whew, that's a mouthful) ... everything dies. Dies so very very badly that I don't even get an error.

It seems obvious to me that I'm having an incredibly dorky sort of syntax issue of some sort... but how do I correctly access private functions from within a class?

Maybe something like: self::do_stuff();

What about declaring and accessing private class variables?

 private $bar = array();

Any help would be welcome.

回答1:

You are calling your function from a static context,

MainReport::get_data($_REQUEST)

therefore $this does not exist while inside that function.

If you want to call another class function while inside a static context, you have to also call it statically.

i.e.

public function get_data($_REQUEST) {
        // do stuff
        $x = MainReport::do_stuff();    
    }

Alternatively, you can create an instance of your class in the original call and use the instance:

$myMainReport = new MainReport();
$myMainReport->get_data($_REQUEST);

Then your class code will work as expected

回答2:

I've just found that self:: does work as well

if I want to have private class variables, I can declare and access them using

private static $foo

and

self::$foo = "foo";

additionally a private function can be accessed with

self::function_foo();

来源：https://stackoverflow.com/questions/3662608/php-calling-a-private-method-from-within-a-class-dying-badly