从不同的类调用模板方法。

Question

我有一个重载运算符

这是来自名为 BTreeLeave 的具体类的方法

 bool BTreeLeave::burn() {
    csv::WriterStream os("products.txt", std::ios_base::out);
    os.set_delimiter(',');
    if (os.is_open()) {

        os << 1693 << NEWLINE;
        os << 15 << 16 << 17 << 20 << NEWLINE;
        os << "s" << "i" << "f" << NEWLINE;
        os << 2 << NEWLINE;
        os << "+" << NEWLINE;
        os << "0" << NEWLINE;
    }

模板功能就是这个

template<typename T>
typename csv::WriterStream& operator << (typename csv::WriterStream& ostm, const T& val)
{    
    if(!ostm.get_after_newline())
        ostm.get_ofstream() << ostm.get_delimiter();    
    ostm.get_ofstream() << val;    
    ostm.set_after_newline(false);    
    return ostm;
}
template<>
inline csv::WriterStream& operator << (typename csv::WriterStream& ostm, const char& val)
{
    if(val==NEWLINE)
    {
        ostm.get_ofstream() << NEWLINE;
            ostm.set_after_newline(true);
    }    
    else
        ostm.get_ofstream() << val;    
    return ostm;
}

我得到的错误是 ‘csv::WriterStream’不是从‘std::basic_ostream’派生的 和 “‘operator

如果我尝试从主函数中调用

Answer 1

你是否尝试以下定义

template<typename T>
typename csv::WriterStream& operator << (typename csv::WriterStream& ostm,  T val)
{    
    if(!ostm.get_after_newline())
        ostm.get_ofstream() << ostm.get_delimiter();    
    ostm.get_ofstream() << val;    
    ostm.set_after_newline(false);    
    return ostm;
}