My peeve is about having operators added to standard types. This increases the chances that using an object the wrong way leads to a bogus result, not a runtime error. A more common programming error I commit is passing a string where a list ist expected. And then I wonder why later operations work on one-character strings.
The standard answer to this seems to be to use unittesting.
I do detect that there is a problem. It just takes longer to find the source of bogus data than to look at a stack trace.
Daniel -- http://mail.python.org/mailman/listinfo/python-list
