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 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).