Reusing PHP string value pointers

Apologies in advance if this is the wrong mailing list. Please direct me to a more appropriate mailing list if there is one :-) When a PHP string variable is changed via a PHP script, such as: $foo = 'new value'; what happens to the `value.str.val' pointer internally? Is it possible to have the new value assigned to the same `value.str.val' pointer that the variable is currently using instead of having that pointer replaced by a pointer to the new value? I have an internal function that binds to a particular pointer address, from which it reads data at a later point. I'd like to allow the value at that address to be modified by assignment from within a PHP script. The following PHP pseudocode is a simple example of this concept: $foo = 'my value'; bind_value(&$foo); // a pointer to foo's value is stored internally. print_value(); // output 'my value', which is the current value of the pointer. $foo = 'a new value'; print_value(); // output 'a new value', which is the new value of the pointer. In other words, I need the new value copied to the same pointer address as the old value. I know that it's possible to retrieve the value of a variable via a hash/list lookup on the variable name, but the pointer is being passed to a function outside the scope of this module, and that function expects it to "just work" with a pre-designated string pointer. Any suggestions and/or clarification would be greatly appreciated. Thanks, Marshall