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2C++ exceptions for long control transfers
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4
5Normally Duktape uses ``setjmp()`` / ``longjmp()`` or their variants for
6internal long control transfers.  One downside of these functions is that
7C++ automatic destructors (scope-based resource management, SBRM, a special
8case of RAII) in Duktape/C functions won't be executed which is awkward for
9C++ programmers.
10
11When ``DUK_USE_CPP_EXCEPTIONS`` (``DUK_OPT_CPP_EXCEPTIONS``) is defined, and
12both Duktape and application code is compiled using a C++ compiler, Duktape
13uses C++ ``try-catch`` and ``throw`` for internal long control transfers.
14This allows automatic destructors to run as expected.  The config option is
15not enabled by default because C++ exceptions are sometimes disabled even
16when a C++ compiler is used (e.g. for performance reasons).
17
18The ``cpp_exceptions.cpp`` example illustrates how C++ exceptions can be
19used in Duktape/C functions at the moment:
20
21* Duktape uses C++ try/catch/throw internally; this is not visible to user
22  code directly.
23
24* Automatic destructors (scope-based resource management) work as expected.
25
26* C++ exceptions can be used in Duktape/C functions normally, but user
27  exceptions must be caught before they reach Duktape.  If this is not
28  done, such exceptions are caught by Duktape and converted to API errors
29  (in other words, they won't propagate "through" Duktape at the moment).
30