Updated almost 13 years ago by Knödlseder Jürgen

• Exceptions
  • Logic exceptions
  • Runtime exceptions
  • Example code

Exceptions¶

GammaLib implements error handling using exceptions. The exceptions are implemented by the GException class. GammaLib distinguishes between logic exceptions and runtime exceptions.

Logic exceptions¶

Logic exceptions occur in situations that a client could have tested. They comprise:

• invalid_value: a value is invalid
• invalid_argument: an argument passed to a method or a function is invalid
• out_of_range: a value is outside its valid range
• fits_error: an error occurred in a cfitsio routine

Runtime exceptions¶

Runtime exceptions occur in situations that a client can not test. They comprise:

• underflow_error
• overflow_error
• feature_not_implemented: the requested feature is not yet implemented in GammaLib

Example code¶

Below an example code that illustrates how exceptions should be implemented:

    if (num != m_cube.nmaps() ) {
        std::string msg = "Number of energies in 'ENERGIES' extension" 
                          " ("+gammalib::str(num)+") does not match the" 
                          " number of maps ("+gammalib::str(m_cube.nmaps())+"" 
                          " in the map cube.\n" 
                          "The 'ENERGIES' extension table shall provide" 
                          " one enegy value for each map in the cube.";
        throw GException::invalid_value(G_LOAD, msg);
    }

An error message should be composed using a std::string. This message is then passed to invalid_value, invalid_argument or any of the other standard exceptions. The G_LOAD macro defines the name of the method that actually throws the exception (and is defined in the header of the .cpp file):

#define G_LOAD                 "GModelSpatialDiffuseCube::load(std::string&)" 

Note that arguments are given in this definition without the const declaration and without the parameter name. If more than a single parameter exists, the parameter should be separated by a blank character:

#define G_MC          "GModelSpatialDiffuseCube::mc(GEnergy&, GTime&, GRan&)"