This is a bit late, but I just want to point out that since PHP 5.3, it is actually possible to override internal functions without using a PHP extension.
The trick is that you can redefine an internal PHP function inside a namespace. It’s based on the way PHP does name resolution for functions:
Inside namespace (say A\B), calls to unqualified functions are resolved at run-time. Here is how a call to function foo() is resolved:
- It looks for a function from the current namespace: A\B\foo().
- It tries to find and call the global function foo()