对于通过引用接受参数的方法，使用bind1st [英] Using bind1st for a method that takes argument by reference

问题描述

我有这样的结构：

struct A {
    void i(int i) {}
    void s(string const &s) {}
};

现在，当我尝试这样：

bind1st(mem_fun(&A::i), &a)(0);
bind1st(mem_fun(&A::s), &a)("");

第一行编译成功，但第二行产生错误：

The first line compiles OK, but the second generates an error:

c:\program files (x86)\microsoft visual studio 10.0\vc\include\xfunctional(299): error C2535: 'void std::binder1st<_Fn2>::operator ()(const std::basic_string<_Elem,_Traits,_Ax> &) const' : member function already defined or declared
          with
          [
              _Fn2=std::mem_fun1_t<void,A,const std::string &>,
              _Elem=char,
              _Traits=std::char_traits<char>,
              _Ax=std::allocator<char>
          ]
          c:\program files (x86)\microsoft visual studio 10.0\vc\include\xfunctional(293) : see declaration of 'std::binder1st<_Fn2>::operator ()'
          with
          [
              _Fn2=std::mem_fun1_t<void,A,const std::string &>
          ]
          c:\work\sources\exception\test\exception\main.cpp(33) : see reference to class template instantiation 'std::binder1st<_Fn2>' being compiled
          with
          [
              _Fn2=std::mem_fun1_t<void,A,const std::string &>
          ]

可能有什么问题？如何解决？

What could be the problem? How could I fix it?

修改：

参数是一个问题。因此，如果我将 i 方法更改为 void i（int& i）{}

It seems that any reference argument is a problem. So if I change the i method to void i(int &i) {} I get a similar error.

推荐答案

std :: bind1st和std :: bind2nd不接受带引用参数的函数，这些论点。您可以

std::bind1st and std::bind2nd don't accept functors which take reference arguments, because they themselves form references to these arguments. You can

1. 使用指针代替函数输入


2. 使用boost :: bind


3. 接受复制字符串的性能成本

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