Evaluate from within a coroutine an expression which results in a type matching the following customisation points, continuing execution 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.

The difference between the BOOST_OUTCOME_CO_TRYV(expr) and BOOST_OUTCOME_CO_TRY(expr) editions is that the latter will set a variable if two or more macro arguments are present (see BOOST_OUTCOME_CO_TRY(var, expr) ). The former requires the T to be void.

Hints are given to the compiler that the expression will be unsuccessful. If you expect success, you should use BOOST_OUTCOME_CO_TRYV(expr) instead.

An internal temporary to hold the value of the expression is created, which generally invokes a copy/move. If you wish to never copy/move, you can tell this macro to create the internal temporary as a reference instead.

Overridable: Not overridable.

Definition: Firstly the expression’s temporary is bound to a uniquely named, stack allocated, auto &&. If that reference’s bound object’s try_operation_has_value() is false, immediately execute return try_operation_return_as(propagated unique reference);, propagating the rvalue/lvalue/etc-ness of the original expression.

Header: <boost/outcome/try.hpp>