Mittens

Mittens is a cross-platform, C++ header-only library for centralized handling of exceptions, particularly along module boundaries.

Robust software needs to be able to handle exceptions as gracefully as possible. This might include last-minute error logging, alternate notification mechanisms (e.g. via the JVM) etc.

An unexpected exit out of main() or an exception escaping from a DLL, COM or JNI function call can cause severe havoc. Module boundaries are stress-points where escaped exceptions should be firmly handled. Dynamically linked libraries (DLLs) export multiple C-like functions forming the dynamic module boundaries. Here, in particular, we would like a uniform and consistent way of handling exceptions. This often requires a lot of copy-paste code since try-catch statements do not naturally compose nor can they be easily encapsulated.

Mittens is a generic header-only library that allows try-catch statement composition, ordering and nesting with customizable actions per exception type. These composite exception handlers can be defined once and reused multiple times where needed.

Overview

Features

Centralized, uniform, maintainable, consistent and composable exception handling;
Support both portable cross-platform and platform-specific code;
Write robust, well ordered, exception-type-specific custom code;
Particularly useful along module boundaries: e.g command-line applications and dynamically loaded libraries (DLLs, shared-object .so, Android JNI, etc.)

TL;DR: Show Me the Code!

#include "common_handlers.hpp"

auto handleIt = mittens::all_catcher               (-1, []()       { std::cerr << "Caught exception of unknown type!"   << std::endl; }, 
                   mittens::std_exception_handler  (-2, [](auto& e){ std::cerr << "Caught std::exception: " << e.what() << std::endl; },
                      mittens::generic_handler<int>(-3, [](auto& e){ std::cerr << "Caught thrown `int` = "  << e        << std::endl; })));

int main() try
{
   throw std::runtime_error("Goodbye World, Hello Mittens!");
   return EXIT_SUCCESS;
}
catch (...) 
{  return handleIt(); }

Application prints: Caught std::exception: Goodbye World, Hello Mittens! and the app return value will be -2.

See the Tutorial for more.

Integration

Single header file generic_exception_handler.hpp + optional helper header (common_handlers.hpp).
Cross platform: Windows, Linux OSX;
No external dependencies (but unit tests use Boost.Test);
BSD License

Epilogue