Robustness-oriented programming has the following requirements or advantages: processing is not the desired behavior and error termination even terminate execution, but also precise / unambiguous show users a comprehensive Error messages facilitate debug
Robustness principle: Always assume that a malicious user to user, assuming that their code will fail to imagine the user as a child, you may note that the output anything, because the users are children, it is best to return an error message to the user, but also detailed and accurate unambiguous! Their code to be conservative behavior of the user to open.
In this regard, reflected in the terms of the code, you need to make policy, it is to write multiple branches to check or detect errors error.