1

从 VC10 迁移到 VC11 时，以下代码无法编译。

#include <algorithm>
#include <functional>
#include <vector>

using namespace std;
using namespace std::placeholders;

typedef std::function<void(int)> CB;


int main()
{
    vector<CB> m_CBs;
    int m_LongPressGesture;

  for_each(m_CBs.begin(), m_CBs.end(), bind(&CB::operator(), _1, m_LongPressGesture));
    return 0;
}

错误输出是非法间接。这是完整的输出。

1>------ Build started: Project: CompileError, Configuration: Debug Win32 ------
1>Build started 2/12/2013 4:32:56 PM.
1>InitializeBuildStatus:
1>  Touching "Debug\CompileError.unsuccessfulbuild".
1>ClCompile:
1>  main.cpp
1>c:\program files (x86)\microsoft visual studio 11.0\vc\include\functional(1269): error C2100: illegal indirection
1>          c:\program files (x86)\microsoft visual studio 11.0\vc\include\functional(1152) : see reference to function template instantiation '_Rx std::_Pmf_wrap<_Pmf_t,_Rx,_Farg0,_V0_t,_V1_t,_V2_t,_V3_t,_V4_t,_V5_t,<unnamed-symbol>>::operator ()<std::function<_Fty>>(_Wrapper &,_V0_t) const' being compiled
1>          with
1>          [
1>              _Rx=void,
1>              _Pmf_t=void (__thiscall std::_Func_class<void,int>::* )(int) const,
1>              _Farg0=std::_Func_class<void,int>,
1>              _V0_t=int,
1>              _V1_t=std::_Nil,
1>              _V2_t=std::_Nil,
1>              _V3_t=std::_Nil,
1>              _V4_t=std::_Nil,
1>              _V5_t=std::_Nil,
1>              <unnamed-symbol>=std::_Nil,
1>              _Fty=void (int),
1>              _Wrapper=std::function<void (int)>
1>          ]
1>          c:\program files (x86)\microsoft visual studio 11.0\vc\include\functional(1152) : see reference to function template instantiation '_Rx std::_Pmf_wrap<_Pmf_t,_Rx,_Farg0,_V0_t,_V1_t,_V2_t,_V3_t,_V4_t,_V5_t,<unnamed-symbol>>::operator ()<std::function<_Fty>>(_Wrapper &,_V0_t) const' being compiled
1>          with
1>          [
1>              _Rx=void,
1>              _Pmf_t=void (__thiscall std::_Func_class<void,int>::* )(int) const,
1>              _Farg0=std::_Func_class<void,int>,
1>              _V0_t=int,
1>              _V1_t=std::_Nil,
1>              _V2_t=std::_Nil,
1>              _V3_t=std::_Nil,
1>              _V4_t=std::_Nil,
1>              _V5_t=std::_Nil,
1>              <unnamed-symbol>=std::_Nil,
1>              _Fty=void (int),
1>              _Wrapper=std::function<void (int)>
1>          ]
1>          c:\program files (x86)\microsoft visual studio 11.0\vc\include\algorithm(24) : see reference to function template instantiation 'void std::_Bind<_Forced,_Ret,_Fun,_V0_t,_V1_t,_V2_t,_V3_t,_V4_t,_V5_t,<unnamed-symbol>>::operator ()<std::function<_Fty>&>(std::function<_Fty>)' being compiled
1>          with
1>          [
1>              _Forced=true,
1>              _Ret=void,
1>              _Fun=std::_Pmf_wrap<void (__thiscall std::_Func_class<void,int>::* )(int) const,void,std::_Func_class<void,int>,int,std::_Nil,std::_Nil,std::_Nil,std::_Nil,std::_Nil,std::_Nil>,
1>              _V0_t=std::_Ph<1> &,
1>              _V1_t=int &,
1>              _V2_t=std::_Nil,
1>              _V3_t=std::_Nil,
1>              _V4_t=std::_Nil,
1>              _V5_t=std::_Nil,
1>              <unnamed-symbol>=std::_Nil,
1>              _Fty=void (int)
1>          ]
1>          c:\program files (x86)\microsoft visual studio 11.0\vc\include\algorithm(24) : see reference to function template instantiation 'void std::_Bind<_Forced,_Ret,_Fun,_V0_t,_V1_t,_V2_t,_V3_t,_V4_t,_V5_t,<unnamed-symbol>>::operator ()<std::function<_Fty>&>(std::function<_Fty>)' being compiled
1>          with
1>          [
1>              _Forced=true,
1>              _Ret=void,
1>              _Fun=std::_Pmf_wrap<void (__thiscall std::_Func_class<void,int>::* )(int) const,void,std::_Func_class<void,int>,int,std::_Nil,std::_Nil,std::_Nil,std::_Nil,std::_Nil,std::_Nil>,
1>              _V0_t=std::_Ph<1> &,
1>              _V1_t=int &,
1>              _V2_t=std::_Nil,
1>              _V3_t=std::_Nil,
1>              _V4_t=std::_Nil,
1>              _V5_t=std::_Nil,
1>              <unnamed-symbol>=std::_Nil,
1>              _Fty=void (int)
1>          ]
1>          c:\program files (x86)\microsoft visual studio 11.0\vc\include\algorithm(33) : see reference to function template instantiation 'void std::_For_each<std::function<_Fty>*,_Fn1>(_InIt,_InIt,_Fn1 &)' being compiled
1>          with
1>          [
1>              _Fty=void (int),
1>              _Fn1=std::_Bind<true,void,std::_Pmf_wrap<void (__thiscall std::_Func_class<void,int>::* )(int) const,void,std::_Func_class<void,int>,int,std::_Nil,std::_Nil,std::_Nil,std::_Nil,std::_Nil,std::_Nil>,std::_Ph<1> &,int &,std::_Nil,std::_Nil,std::_Nil,std::_Nil,std::_Nil>,
1>              _InIt=std::function<void (int)> *
1>          ]
1>          c:\users\jedwards\documents\visual studio 2012\projects\compileerror\compileerror\main.cpp(16) : see reference to function template instantiation '_Fn1 std::for_each<std::_Vector_iterator<_Myvec>,std::_Bind<_Forced,_Ret,_Fun,_V0_t,_V1_t,_V2_t,_V3_t,_V4_t,_V5_t,<unnamed-symbol>>>(_InIt,_InIt,_Fn1)' being compiled
1>          with
1>          [
1>              _Fn1=std::_Bind<true,void,std::_Pmf_wrap<void (__thiscall std::_Func_class<void,int>::* )(int) const,void,std::_Func_class<void,int>,int,std::_Nil,std::_Nil,std::_Nil,std::_Nil,std::_Nil,std::_Nil>,std::_Ph<1> &,int &,std::_Nil,std::_Nil,std::_Nil,std::_Nil,std::_Nil>,
1>              _Myvec=std::_Vector_val<std::_Simple_types<std::function<void (int)>>>,
1>              _Forced=true,
1>              _Ret=void,
1>              _Fun=std::_Pmf_wrap<void (__thiscall std::_Func_class<void,int>::* )(int) const,void,std::_Func_class<void,int>,int,std::_Nil,std::_Nil,std::_Nil,std::_Nil,std::_Nil,std::_Nil>,
1>              _V0_t=std::_Ph<1> &,
1>              _V1_t=int &,
1>              _V2_t=std::_Nil,
1>              _V3_t=std::_Nil,
1>              _V4_t=std::_Nil,
1>              _V5_t=std::_Nil,
1>              <unnamed-symbol>=std::_Nil,
1>              _InIt=std::_Vector_iterator<std::_Vector_val<std::_Simple_types<std::function<void (int)>>>>
1>          ]
1>
1>Build FAILED.
1>
1>Time Elapsed 00:00:00.68
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

我唯一能想到的是 bind 是期待一个指针。我尝试了 ref() 但没有任何区别。

谢谢，吉姆

4

2 回答 2

8

听起来像http://connect.microsoft.com/VisualStudio/feedback/details/763571/，目前分配给我。

请注意，技术上不允许获取大多数标准库成员函数的地址（因为实现可以有额外的重载和默认参数）。

实际上会产生更好的代码的一种解决方法是使用 lambdas。Lambda 在 99% 的情况下取代了 bind()，剩下的 1% 用手写函子更好地处理。

于 2013-02-12T21:40:56.927 回答
1

由于 VC 显然有一个错误（感谢 Stephan！），您可以将循环编写为：

for ( auto &cb : m_CBs ) cb ( m_LongPressGesture );

或者：

for_each ( m_CBs.begin(), m_CBs.end(), 
             [m_LongPressGesture] ( const CB &cb ) { cb ( m_LongPressGesture ); } );
于 2013-02-12T22:02:36.230 回答