complex-strings

PHP curly string syntax question

I'm running PHP 5.3.0. I've found that the curly string syntax only works when the first character of the expression is $. Is there a way to include other types of expressions (function calls, etc)? Trivial example: <?php $x = '05'; echo "{$x}"; // works as expected echo "{intval($x)}"; // hoped for "5", got "{intval(05)}" ...