The alternative usage of the class--Data encapsulation _php base

Alternative use of classes--encapsulation of data
In general, if you use the classname::p Roperty cannot access the properties of the class, but you can use the method of Classname::method () with the class. Similarly, you cannot use Objectname->property to access variables in a class's method. With this feature, we can save some data in a class, a bit like the private properties of C + +.
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Class Data {
function value ($var) {
static $d = Array ();
if (Func_num_args () > 1) {
$d [$var] = Func_get_arg (1);
}else {
return $d [$var];
}
}
}
Test:
Data::value ("A", 1);
Data::value ("B", 2);
Echo Data::value ("a");
echo Data::value ("B");
?>