nojhan / exceptions

C++ exception class and macros with easy nested declaration and localisation data

Better exception declaration and use

A C++ exception class and macros with easy nested declaration and localisation data.

The point of this system is to permits to easily add to exceptions instances some informations about where (in the source code) the exceptions are thrown.

It also ease declaration of new exception classes and their use.

Example

#include <iostream>
#include <iomanip>

#include <exceptions/exceptions.h>

// Use this macro to build up your hierarchy of exceptions
EXCEPTION( Exception, Existential_Observation );
    EXCEPTION( Existential_Observation, Buddhist_Observation );
        EXCEPTION( Buddhist_Observation, Zen_Observation );
    EXCEPTION( Existential_Observation, Pastafarism_Observation );

int main()
{
    try {
        double pi = 3.1415926535;
        // Use this macro to easily throw an exception with a dynamic message
        RAISE( Pastafarism_Observation, std::setprecision(3) << "Shit happens with " << pi << " noodly appendages" );
    } catch( Existential_Observation & e ) {
        std::cerr << e.what() << std::endl;
    }
}

Will output:

[:~/code/exceptions] master* ± g++ example.cpp && ./a.out
Shit happens with 3.14 noodly appendages (<Pastafarism_Observation> in main at example.cpp:18)

Explanations

Declaration

It permits a one-line declaration of new exceptions, derived from existing ones.

Example:

EXCEPTION( Exception, Existential_Observation );
    EXCEPTION( Existential_Observation, Pastafarism_Observation );

If you catch an Existential_Observation, you may thus catch an Pastafarism_Observation also.

Note that the base Exception class derivate from std::exception and uses the standard what interface (more or less like std::runtime_error and std::logical_error).

Location

To add location information, it uses compilers macros that indicates the current function, file and line (__FUNCTION__, __FILE__ and __LINE__ for g++) and merge those information with the given description returned by the what standard method.

You did not need to remember the name of those macros, they are available in the E_INFOS macro, that fit with the constructor of the Exception class.

Example:

throw Existential_Observation( "Shit happens", E_INFOS );

Use

It also provides a macro to easily throw an exception that permits to use dynamic streamed messages inline and without having to specify E_INFOS.

Example:

RAISE( Pastafarism_Observation, "Shit happens with " << 42 << " noodly appendages" );