of editing code
that is currently in use in a production
environment. This can result in users
information, error message
s, and any and all other kinds of strangeness.
This is usually a bad idea. One should always hack on test code, and copy the test code over to the live code when the hacking is completed and the changes are perfected.
The thrill of hacking on live code is hard to beat, though. I confess to doing it sometimes if the changes are quick and innocuous. Not only that, but the debugging help provided by bitching users is second-to-none.