php类变量交互

Question

That's the problem, how can I call a class variable from a class function? Let me explain better:

    <?php

class Mine
{

    private $g = 'gg';
    const COSTANTE = 'valo';

    public static function sayHello()
    {
        echo self::COSTANTE;
        echo '<br>';
        echo $this->g;
    }
}
$h = new Mine();
$h->sayHello();
$h::sayHello();
?>

when I run this, it just print the constant COSTANTE.... Why it doesn't print the variable g?

Answer 1

Turn on error reporting ( error_reporting ( E_ALL ); ), and you should receive the following error:

Fatal error: Using $this when not in object context

The pseudo-variable $this is a reference to the calling object, and is available from within an object context.

self is used to access the current class, since static functions can be called without the actual object instance, when the method is called statically $this reference does not exists.

A method declared as static can be accessed with an instantiated class object ( but it is always executed in a static context ), a property declared as static cannot.