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- [#nullary_metafunction]
- [section Nullary template metafunction]
- A ['nullary template metafuncion] is a [link metafunction template metafunction]
- taking 0 arguments. It is a type with a nested type called `type`, which is the
- return value of the nullary metafunction. For example:
- struct always13
- {
- using type = std::integral_constant<int, 13>;
- };
- This metafunction is called `always13`. It is a nullary metafunction, because it
- takes no arguments. It always returns `std::integral_constant<int, 13>`.
- To call this metafunction, one has to access its `::type`. For example:
- always13::type
- The above example calls the metafunction to get
- `std::integral_constant<int, 13>`.
- [endsect]
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