Jason E. Sweat's weblog

I ran across a SitePoint post where a user wanted to chain calls to returned objects in PHP4, similar to what you can now do in PHP5. Of course PHP4 does not allow this syntax, but the user came up with the idea of calling a function with the base object, and the series of calls as a string argument. The function would then parse the string and apropriatly eval() the calls. I took his idea as a springboard, and re-wrote it to use recursion for arbitrary call depth.

Here are the functions:

<?php
function &chain(&$obj, $call) {
        return call_chain($obj, explode('->',$call));
}
function &call_chain(&$obj, $stack) {
        if ($stack) {
                eval('$new_obj =& $obj->'.array_shift($stack).';');
                return call_chain($new_obj, $stack);
        } else {
                return $obj;
        }
}

?>

And here is a cheesy example:
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From the internals list. Downloads here. But a word of caution, I have heard grumblings of problems from people migrating to 4.3.10 on some message boards I follow.
Update: If you experience any problems with upgrading to PHP 4.3.10, make sure you have the latest Zend Optimizer if you are running it. It seems there are problems with older versions of Zend Optimizer and foreach().

PHP Development Team would like to announce the immediate release of PHP
4.3.10 and 5.0.3. These are maintenance releases that in addition to
non-critical bug fixes address several very serious security issues.

These include the following:

CAN-2004-1018 – shmop_write() out of bounds memory write access.
CAN-2004-1018 – integer overflow/underflow in pack() and unpack() functions.
CAN-2004-1019 – possible information disclosure, double free and
negative reference index array underflow in deserialization code.
CAN-2004-1020 – addslashes not escaping