State preserving IO manipulator example

manips.h

/*
 * manips.h:
 *
 */
#pragma once
#ifndef manips_h__f1fd7c75_0593_40cb_9c6b_848e2f1cd153
#define manips_h__f1fd7c75_0593_40cb_9c6b_848e2f1cd153  1

#include <iostream>
#include <iomanip>

template <typename T_>
    class put_hex_ {
    private:
        int width_ ;
        const T_ &      value_ ;
    public:
        put_hex_ (const T_ &value, int width) : width_ (width), value_ (value) {
            /* NO-OP */
        }
        std::ostream &      write (std::ostream &out) const {
            std::ios::fmtflags      f = out.setf (std::ios::hex, std::ios::basefield) ;
            char    fill = out.fill ('0') ;
            out << std::setw (width_) << value_ ;
            out.fill (fill) ;
            out.setf (f, std::ios::basefield) ;
            return out ;
        }
    } ;

template <typename T_>
    std::ostream &  operator << (std::ostream &out, const put_hex_<T_> &arg) {
        return arg.write (out) ;
    }

template <typename T_>
    put_hex_<T_>    put_hex (const T_ &value, int width = 0) {
        return put_hex_<T_> (value, width) ;
    }

#endif  /* manips_h__f1fd7c75_0593_40cb_9c6b_848e2f1cd153 */