Question

I m 接手推进教学,用zy光功能为例处理这个问题。举例说:

// Define a pow_fun function object
template<int Exp> // , typename Func>
struct pow_fun
{
    typedef double result_type;
    double operator()(double d) const
    {
        return pow(d, Exp);
    }
};

// Define a lazy pow() function for the calculator DSEL.
// Can be used as: pow< 2 >(_1)
template<int Exp, typename Arg>
typename proto::result_of::make_expr<
    proto::tag::function  // Tag type
  , pow_fun<Exp>          // First child (by value)
  , Arg const &           // Second child (by reference)
>::type const
mypow(Arg const &arg)
{
    return proto::make_expr<proto::tag::function>(
        pow_fun<Exp>()    // First child (by value)
      , boost::ref(arg)   // Second child (by reference)
    );    
}

现在,如果我尝试的话

proto::display_expr( mypow<2>(_1) );

the compiler complains that it doesn t have operator<< for the function expression. How do I define one?

感谢。

编辑错误是:

: 页: 1

Answer 1

哪一个预言是? 最近的拖船不需要加固;加固;如果需要,超负荷再充气地打上标识。您能否发出实际错误信息?

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