How to register an exception translation?


Boost.Python provides functionality to translate any C++ exception to a Python one. Py++ provides a convenient API to do this.

By the way, be sure to take a look on “troubleshooting guide - exceptions”. The guide will introduces a complete solution for handling exceptions within Python scripts.


Boost.Python exception translator documentation contains a complete explanation what should be done. I will use that example, to show how it could be done with Py++:

from pyplusplus import module_builder_t

mb = module_builder_t( ... )
my_exception = mb.class_( 'my_exception' )

translate_code = 'PyErr_SetString(PyExc_RuntimeError, exc.what();'
my_exception.exception_translation_code = translate_code

That’s all, really. Py++ will generate for you the translate function definition and than will register it.

I think this is a most popular use case - translate a C++ exception to a string and than to create an instance of Python built-in exception. That is exactly why Py++ provides additional API:

mb = module_builder_t( ... )
my_exception = mb.class_( 'my_exception' )

my_exception.translate_exception_to_string( 'PyExc_RuntimeError', 'exc.what()')

The first argument of translate_exception_to_string method is exception type, The second one is a string - code that converts your exception to const char*.

As you see, it is really simple to add exception translation to your project.

One more point, in both pieces of code I used “exc” as the name of my_exception class instance. This is a predefined name. I am not going to change it without any good reason, any time soon :-).