Is it possible to replace (monkeypatch) PHP functions?

Question

You can do this in Python, but is it possible in PHP?

>>> def a(): print 1
... 
>>> def a(): print 2
... 
>>> a()
2

Answer 1

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:

1. It looks for a function from the current namespace: A\B\foo().
2. It tries to find and call the global function foo()