30 lines
1.4 KiB
ReStructuredText
30 lines
1.4 KiB
ReStructuredText
=========================================
|
|
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`` 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).
|