BOOST_OUTCOME_TRYX(expr)
Evaluate an expression which results in a type matching the following customisation points, emitting the T
if successful, immediately returning try_operation_return_as(X)
from the calling function if unsuccessful:
BOOST_OUTCOME_V2_NAMESPACE::
try_operation_has_value(X)
BOOST_OUTCOME_V2_NAMESPACE::
try_operation_return_as(X)
BOOST_OUTCOME_V2_NAMESPACE::
try_operation_extract_value(X)
Default overloads for these customisation points are provided. See the recipe for supporting foreign input to BOOST_OUTCOME_TRY
.
Hints are given to the compiler that the expression will be successful. If you expect failure, you should use BOOST_OUTCOME_TRYX_FAILURE_LIKELY(expr)
instead.
Availability: GCC and clang only. Use #ifdef BOOST_OUTCOME_TRYX
to determine if available.
Overridable: Not overridable.
Definition: See BOOST_OUTCOME_TRYV(expr)
for most of the mechanics.
This macro makes use of a proprietary extension in GCC and clang to emit the T
from a successful expression. You can thus use BOOST_OUTCOME_TRYX(expr)
directly in expressions e.g. auto x = y + BOOST_OUTCOME_TRYX(foo(z));
.
Be aware there are compiler quirks in preserving the rvalue/lvalue/etc-ness of emitted T
’s, specifically copy or move constructors may be called unexpectedly and/or copy elision not work as expected. If these prove to be problematic, use BOOST_OUTCOME_TRY(var, expr)
instead.
Header: <boost/outcome/try.hpp>