Unchecked Exceptions: Can the Programmer be Trusted to Document Exceptions?

The emergence of exception handling mechanisms in modern programming languages made available a different way of communicating errors between procedures. For years, programmers trusted in the correct documentation for error codes returned by procedures to correctly handle erroneous situations. Now, they have to focus on the documentation of exceptions for the same effect. But to which extent can exception documentation be trusted? Moreover, is there enough documentation for exceptions? And in which way do these questions relate to the checked vs. unchecked exceptions discussion? For a given set of Microsoft .NET applications, code and documentation were thoroughly parsed and compared. This showed that exception documentation tends to be scarce and of poor quality when existent. In particular, it showed that 90% of exceptions are undocumented. Furthermore, programmers were demonstrated to be keener to document exceptions they explicitly throw while typically leaving exceptions resulting from method calls undocumented. These results are a contribution to the assessment of the effectiveness of the unchecked exceptions approach.