Exceptions for Error Reporting

1. Debug mode: Exceptions thrown by the code (no by STL functions) must be inside a debug mode condition set in the ADIOS class constructor. Applications are encourages to turn these on when integrating with ADIOS2.
2. Standard exception: Throw C++ standard exceptions for error handling, do not throw integers. This is helpful as it allows handling of different exception types in different ways. In rare cases a custom exceptions must be defined/declared.
   • Don't

     •  throw   1;

   • Do

     •  throw std::invalid_argument ( "ERROR: group was not   
                                     previously declared, in call to Write" );

3. Document exceptions: All error exceptions must start with "ERROR: ". Use informative and precise messages for exception handling to complement the nature of the exception to help the user identify and fix the issue.
   • Don't

     •  throw    std::invalid_argument  ( "ERROR: invalid input for CompressionParameter"  );

   • Do

     •  throw std::invalid_argument( "ERROR: bzip2 
                     CompressionParameter must be an unsigned int between 0 and 9,  
                     in call to Compress""  );