Is there a way to bind variables? PHP 5

Question

Using PHP 5 I would like to know if it is possible for a variable to dynamically reference the value of multiple variables?

For example

    <?php
    $var = "hello";
    $var2 = " earth";
    $var3 = $var.$var2 ;
    echo $var3; // hello earth

Now if I change either $var or $var2 I would like $var3 to be updated too.

    $var2 =" world";  
    echo $var3; 

This still prints hello earth, but I would like to print "hello world" now :(

Is there any way to achieve this?

Answer 1

No, there is no way to do this in PHP with simple variables. If you wanted to do something like this in PHP, what you'd probably do would be to create a class with member variables for var1 and var2, and then have a method that would give you a calculated value for var3.