The Boost_pp_seq_for_each of Boost learning

Use:

A Boost_pp_seq_for_each macro that expands the parameters of a sequence by the specified macro in turn.

Grammar:

Boost_pp_seq_for_each (macro, data, SEQ)

variables:

Macro

A ternary macro defined in the Format macro(R, data, elem). The macro is boost_pp_seq_for_each as each element in the SEQ is expanded. To expand the macro, you need to use the next boost_pp_for Duplicate, alternate data, and current element.

Data

Backup data, used to pass to macro

Seq

Used to expand the macro by which sequence

Usage:

Boost_pp_seq_for_each is a duplicate of a macro.

If the sequence is (a) (b) (c), expand to:

Macro(R, Data, a) Macro(R, Data, b) Macro(R, Data, C)

If higher efficiency is required, use boost_pp_seq_for_each_r

Header file:

<boost/preprocessor/seq/for_each.hpp>

Example code:

1. Example 1

#include <boost/preprocessor/cat.hpp> #include <boost/preprocessor/seq/for_each.hpp> #define SEQ (w) (x) ( y) (z) #define MACRO (R, data, Elem) Boost_pp_cat (elem, data) Boost_pp_seq_for_each (macro, _, SEQ)//expands to W_ x_ y_ z_

2. Example 2

#include <boost/preprocessor/cat.hpp> #include <boost/preprocessor/seq/for_each.hpp> #define SEQ (w) (x) ( y) (z) #define MACRO (R, data, Elem) elem::getinstance () Boost_pp_seq_for_each (macro, _, SEQ)//Expands to W::getinstance () X::getinstance () y::getinstance () z::getinstance ()

The Boost_pp_seq_for_each of Boost learning