我可以更改 PHP 中 function 内的局部变量的值吗？

Question

I was reading an article about Data Encapsulation in PHP, and the author explained in such a way that it made me to wonder if this is really possible? here is what he said.

The primary purpose of encapsulation (scope) is to ensure that you write code that can't be broken. This applies to scope in general, so let me use a simpler example of a local variable inside a function:

function xyz ($x) {
  $y = 1;
  while ($y <= 10) {
    $array[] = $y * $x;
    $y++;
  }
  return $array;
}

The purpose of this function is to pass a number and return an array. The example code is pretty basic. In order for function xyz() to be dependable, you need to be guaranteed that it does the exact same thing every time. So what if someone had the ability to from the outside change that initial value of $y or $array? Or even $x? If you were able to do that from outside of the function, you could no longer guarantee what that function is returning.

Now this made me wonder can i really change the value of local variable sitting inside the function without using any argument as demonstrated above?? if it is possible how do i do it?

thank you..

Answer 1

For this example you wouldn't be able to change any of the variables, because they're all declared inside of the function.

But if you had a class with a public class variable, you could change that outside of the class if you wanted to. (That's bad form and might screw a lot of things up, though.)

Answer 2

Unless you add a magic setter method ( __set($key,$value) ), and configure it in such a way that you can access that internal member, then no. You can change the key when you make the function if you're using some form of factory, but if you haven't made it public, there's no other way.

The only visible exception would be with a singleton factory: you could make a new instance of your singleton method with different parameters (changing it everywhere else), but I doubt you'd be likely to do that with a method.