guard class for ostream state flags

ostream_guard.h

#pragma once

#include <ostream>

/// RAII guard class for saving and restoring ostream state
class ostream_guard final
{
    std::ostream *os_;
    std::streamsize width_;
    std::streamsize precision_;
    std::ios::fmtflags flags_; // Moved here to reduce padding
    char fill_;

public:
    explicit ostream_guard(std::ostream& os) 
        : os_(&os),
        width_(os.width()),
        precision_(os.precision()),
        flags_(os.flags()),
        fill_(os.fill())
    {
    }

    ~ostream_guard()
    {
        os_->flags(flags_);
        os_->width(width_);
        os_->precision(precision_);
        os_->fill(fill_);
    }

    ostream_guard(const ostream_guard&) = delete;
    ostream_guard& operator=(const ostream_guard&) = delete;
    ostream_guard(ostream_guard&&) = delete;
    ostream_guard& operator=(ostream_guard&&) = delete;
};