[ceph.git] / ceph / src / boost / libs / metaparse / doc / metaprogramming_value.qbk

[#metaprogramming_value]
[section Template metaprogramming value]

A ['template metaprogramming value] is a
[link nullary_metafunction nullary template metafunction] returning itself.
For example:

  struct void_
  {
    using type = void_;
  };

This template metaprogramming value is called `void_`. It is a nullary
metafunction returning itself as its result. Because of this, it can be treated
as a nullary metafunction and evaluated any number of times. For example 
`void_::type::type::type` is still `void_`.

[endsect]
Commit	Line	Data
7c673cae FG	1	[#metaprogramming_value]
	2	[section Template metaprogramming value]
	3
	4	A ['template metaprogramming value] is a
	5	[link nullary_metafunction nullary template metafunction] returning itself.
	6	For example:
	7
	8	struct void_
	9	{
	10	using type = void_;
	11	};
	12
	13	This template metaprogramming value is called `void_`. It is a nullary
	14	metafunction returning itself as its result. Because of this, it can be treated
	15	as a nullary metafunction and evaluated any number of times. For example
	16	`void_::type::type::type` is still `void_`.
	17
	18	[endsect]
	19