|  | 
boost::log::optional_manip
// In header: <boost/log/utility/manipulators/optional.hpp> template<typename OptionalT, typename NoneT> boost::enable_if_c< is_scalar< OptionalT >::value &&is_scalar< NoneT >::value, optional_manipulator< OptionalT, NoneT >>::type optional_manip(OptionalT opt, NoneT none);
Optional manipulator generator function.
| ![[Note]](../../../../../../doc/src/images/note.png) | Note | 
|---|---|
| Both opt and none objects must outlive the created manipulator object. | 
| Parameters: | 
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| Returns: | Manipulator to be inserted into the stream. |