没有井号的C ++宏定义

Question

Here is a c++ header file I found somewhere else.

#include "opencv\cv.h"
#include <boost/serialization/split_free.hpp>
#include <boost/serialization/vector.hpp>
#include <boost/archive/binary_oarchive.hpp>
#include <boost/archive/binary_iarchive.hpp>

BOOST_SERIALIZATION_SPLIT_FREE(cv::Mat)
namespace boost {
namespace serialization {

/** Serialization support for cv::Mat */
template <class Archive>
void save(Archive & ar, const ::cv::Mat& m, const unsigned int version)
{

    size_t elem_size = m.elemSize();
    size_t elem_type = m.type();

    ar & m.cols;
    ar & m.rows;
    ar & elem_size;
    ar & elem_type;

    const size_t data_size = m.cols * m.rows * elem_size;
    ar & boost::serialization::make_array(m.ptr(), data_size);
}

};
}

My question is: What does the following code mean?

BOOST_SERIALIZATION_SPLIT_FREE(cv::Mat)

Is it a macro definition? Then where is the pound sign "#"?

Answer 1

In short words, it's a macro . BOOST_SERIALIZATION_SPLIT_FREE(my_class) is the macro, which is short for the following free serialize function template:

namespace boost { namespace serialization {
    template<class Archive>
    inline void serialize(
        Archive & ar,
        my_class & t,
        const unsigned int file_version
        ){
            split_free(ar, t, file_version); 
    }
}}

Also note that BOOST_SERIALIZATION_SPLIT_FREE must be used outside of any namespace. Check out here for further info.

Answer 2

宏，用于将序列化函数拆分为保存和加载函数