Lines Matching defs:failure
1722 \section{Understanding failure}
1723 We can distinguish five types of failure\index{failure}, each with its own set of causes and possible remedies.
1776 \subsection{Failure} Probably the most common error symptom is a failure\index{failure} of the application. Instead of producing an answer, the system returns 'no'\index{no}. This is caused by:
1778 \item Calling a user-defined predicate \index{user defined predicate}with the wrong calling pattern. If none of the rules of a predicate matches the calling pattern, then the predicate will fail. Of course, quite often this is intentional (tests for some condition for example). It becomes a problem if the calling predicate does not handle the failure properly. We should know for each predicate that we define if it can fail and make sure that any calling predicate handles that situation.
1782 The best way of finding failures is by code inspection, helped by logging messages which indicate the general area of the failure. If this turns out to be too complex, we may have to use the tracer.
1832 or which can be directed to a log file. This can be useful in ``live'' code, in order to capture information about problems in failure cases.
1948 \item The final code should not use failure-loops\index{failure loop}; they are acceptable for debugging or testing purposes.