Boost C++ Libraries

Convert a value to a boost::system::result<T>.

Synopsis

Defined in header <boost/json/value_to.hpp>

template<
    class T>
result_for< T, value >::type
try_value_to(
    const value& jv);

Description

This function attempts to convert a value to result<T> using

Out of the box the function supports types satisfying SequenceContainer, arrays, arithmetic types, bool, std::tuple, std::pair, std::variant, std::optional, std::monostate, and std::nullopt_t.

Conversion of other types is done by calling an overload of tag_invoke found by argument-dependent lookup. Its signature should be similar to:

result<T> tag_invoke( try_value_to_tag<T>, const value& );

If an error occurs during conversion, the result will store the error code associated with the error. If an exception is thrown, the function will attempt to retrieve the associated error code and return it, otherwise it will return error::exception, unless the exception type is std::bad_alloc, which will be allowed to propagate.

Constraints

! std::is_reference< T >::value

Exception Safety

Strong guarantee.

Template Parameters

Parameters

Return Value

jv converted to result<T>.

See Also

value_to_tag, value_to, value_from, tag_invoke: A general pattern for supporting customisable functions

Convenience header <boost/json.hpp>