If you use preg_replace with the /e option from within a class you may want to call a method of the current class to perform the lookup. Intuativly a user might expect this code to work:

$whatever=preg_replace( $pattern,"$this->whatever('\\1')", $value );

That 2nd parameter is being evaluated outside the current class... In this context "$this" has no meaning outside the object,  So a method like "$this->whatever{foo)" can never be evaluated directly by this command.

The function works fine if you use it according to the instructions - that is you provide it with a globally available function it will work perfectly.

To check version & config of the my offending server:
http://sharesite.stodge.org/test.php