The BOOST_PP_ENUM_z macro represents a reentry into the BOOST_PP_ENUM repetition construct.

#### Usage

BOOST_PP_ENUM_ ## z(count, macro, data)

#### Arguments

z
  The next available BOOST_PP_REPEAT dimension.
count
  The number of repetitious calls to macro. Valid values range from 0 to BOOST_PP_LIMIT_REPEAT.
macro
  A ternary operation of the form macro(z, n, data). This macro is expanded by BOOST_PP_ENUM with the next available repetition depth, the current repetition number, and the auxiliary data argument.
data
  Auxiliary data passed to macro.

#### Remarks

This macro expands to the sequence:
macro(z, 0, data), macro(z, 1, data), ... macro(z, count - 1, data)
At certain times, it may be necessary to perform the concatenation with BOOST_PP_CAT rather than the preprocessor token-pasting operator. This happens when the z value is a macro invocation itself. It needs a delay to allow it to expand. The syntax in such a scenario becomes:
BOOST_PP_CAT(BOOST_PP_ENUM_, z)(count, macro, data)

#### See Also

- BOOST_PP_CAT
- BOOST_PP_ENUM
- BOOST_PP_LIMIT_REPEAT

#### Requirements

Header: <boost/preprocessor/repetition/enum.hpp>

#### Sample Code

    #include <boost/preprocessor/arithmetic/inc.hpp>
    #include <boost/preprocessor/repetition/enum.hpp>

    #define TEXT(z, n, text) text

    #define TTP(z, n, _) \
       template< \
          BOOST_PP_ENUM_ ## z(BOOST_PP_INC(n), TEXT, class) \
       > \
       class T ## n \
       /**/

    BOOST_PP_ENUM(3, TTP, nil)
       /*
          expands to...
          template<class> class T0,
          template<class, class> class T1,
          template<class, class, class> class T2
       */