| ========================================= |
| C++ exceptions for long control transfers |
| ========================================= |
| |
| Normally Duktape uses ``setjmp()`` / ``longjmp()`` or their variants for |
| internal long control transfers. One downside of these functions is that |
| C++ automatic destructors (scope-based resource management, SBRM, a special |
| case of RAII) in Duktape/C functions won't be executed which is awkward for |
| C++ programmers. |
| |
| When ``DUK_USE_CPP_EXCEPTIONS`` (``DUK_OPT_CPP_EXCEPTIONS``) is defined, and |
| both Duktape and application code is compiled using a C++ compiler, Duktape |
| uses C++ ``try-catch`` and ``throw`` for internal long control transfers. |
| This allows automatic destructors to run as expected. The config option is |
| not enabled by default because C++ exceptions are sometimes disabled even |
| when a C++ compiler is used (e.g. for performance reasons). |
| |
| The ``cpp_exceptions.cpp`` example illustrates how C++ exceptions can be |
| used in Duktape/C functions at the moment: |
| |
| * Duktape uses C++ try/catch/throw internally; this is not visible to user |
| code directly. |
| |
| * Automatic destructors (scope-based resource management) work as expected. |
| |
| * C++ exceptions can be used in Duktape/C functions normally, but user |
| exceptions must be caught before they reach Duktape. If this is not |
| done, such exceptions are caught by Duktape and converted to API errors |
| (in other words, they won't propagate "through" Duktape at the moment). |
