Conclusion

The emphasis in this tutorial has been on library development; but Objections can be used for any third-party software. They can be added quickly to software to implement a simple, robust method for handling errors. They do not behave like exceptions, and will not migrate invisibly to formal exception handling. No feature of the language today can implement error handling in a way which will guarantee to migrate naturally to exception handling. At least Objections are simple enough that not much will have to be undone when exceptions are finally in use.