C ++中带有std :: forward的多个参数

Question

我有一个具有5个成员的结构，我用std::forward初始化了所有参数：

#include <iostream>
#include <string>
#include <utility>
struct OutputFilesName {
  template<typename T>
  OutputFilesName(
    T&& result_subdir_name,
    T&& result_TSIM_minus, 
    T&& result_TSIM_plus,
    T&& result_minus_total_dat, 
    T&& result_plus_total_dat,
    T&& result_hdl 
    ) : 
      subdir_name( std::forward<T>(result_subdir_name) ),
      TSIM_minus( std::forward<T>(result_TSIM_minus) ),
      TSIM_plus( std::forward<T>(result_TSIM_plus) ),
      minus_total_dat( std::forward<T>(result_minus_total_dat) ),
      plus_total_dat( std::forward<T>(result_plus_total_dat) ),
      hdl( std::forward<T>(result_hdl) ) {     
  }

  const std::string subdir_name;
  const std::string TSIM_minus;
  const std::string TSIM_plus;
  const std::string minus_total_dat;
  const std::string plus_total_dat;
  const std::string hdl;

  OutputFilesName() = delete;
};

我在主程序中调用该结构：

int main(){    
  OutputFilesName ofn(
    "a",
    "bb",
    "ccc",
    "dddd",
    "eeeee",
    "ffffff"
  );
}

编译器抛出错误，看来参数不能正确解析：

./test_genHoughMap.cc:37:19: error: no matching constructor for initialization of 'OutputFilesName'
  OutputFilesName ofn(
                  ^
./test_genHoughMap.cc:10:3: note: candidate template ignored: deduced conflicting types for parameter 'T'
      ('char const (&)[2]' vs. 'char const (&)[3]')
  OutputFilesName(
  ^
./test_genHoughMap.cc:8:8: note: candidate constructor (the implicit copy constructor) not viable: requires
      1 argument, but 6 were provided
struct OutputFilesName {
       ^
./test_genHoughMap.cc:8:8: note: candidate constructor (the implicit move constructor) not viable: requires
      1 argument, but 6 were provided
./test_genHoughMap.cc:33:3: note: candidate constructor not viable: requires 0 arguments, but 6 were
      provided
  OutputFilesName() = delete;
  ^
1 error generated.

我该如何解决？

Answer 1

问题是您的构造函数对所有参数都使用通用类型T。现在，为第一个参数char[2]推导第二个char[3]发生了什么冲突。如果您通过所有相同长度的st it compiles。

Answer 2

请参阅Marek R