output.txt

~ $ php testforben.php
Foo/__construct called successfully.
Foo/non_static called successfully.
Foo/is_static called successfully.
Foo/is_static called successfully.

Strict Standards: Non-static method Foo::non_static() should not be called statically in /Users/georgestephanis/testforben.php on line 25
Foo/non_static called successfully.
~ $

testforben.php

<?php

error_reporting( E_ALL );

class Foo {

	function __construct() {
		echo __CLASS__ . '/' . __FUNCTION__ . ' called successfully.' . "\r\n";
	}

	function non_static() {
		echo __CLASS__ . '/' . __FUNCTION__ . ' called successfully.' . "\r\n";
	}


	public static function is_static() {
		echo __CLASS__ . '/' . __FUNCTION__ . ' called successfully.' . "\r\n";
	}
}

$foo = new Foo();
$foo->non_static();
$foo->is_static();
Foo::is_static();
Foo::non_static();