Modifying a built-in function for logging purposes

[qwweeeit at yahoo.it]

Hi Greg,
thank for your replay, but I didn't succeed in any way. You must
consider however that I'm not a Python "expert"...
IMHO, it must be a script that change part of the interpreter, and
substitute a new module (py) in the place of the standard one (py or
pyc). The standard module must be saved in order to be able to undo the
changes and go back to the normal behaviour.
The problem is that I don't know if the built-in functions like open
(or file) are written in Python or in C and, besides that, if they can
be modified.
Other solutions which modify the source to be logged, are not
solutions, because it is far simpler to introduce here and there print
statements... 
Bye.