以下代码在 VS2012 中无法编译

class Zot
{
public:
    int A() { return 123; }
};

int _tmain(int argc, _TCHAR* argv[])
{
    std::function<int (Zot*)> fn = &Zot::A;
    return 0;
}

但是，将分配更改为

    std::function<int (Zot*)> fn = std::bind(&Zot::A, std::placeholders::_1);

有效。

有很多在线示例显示了原始语法。 C++11 规范是否更改了某些内容以禁止使用此语法？

作业是否有有效的缩写形式？

编辑:编译器错误(针对可恢复性略微编辑)是:

1>vc\include\functional(515): error C2664: 'std::_Func_class<_Ret,_V0_t>::_Set' : cannot convert parameter 1 from '_Myimpl *' to 'std::_Func_base<_Rx,_V0_t> *'
1>          with
1>          [
1>              _Ret=int,
1>              _V0_t=Zot *
1>          ]
1>          and
1>          [
1>              _Rx=int,
1>              _V0_t=Zot *
1>          ]
1>          Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast
1>          vc\include\functional(515) : see reference to function template instantiation 'void std::_Func_class<_Ret,_V0_t>::_Do_alloc<_Myimpl,_Fret(__thiscall Zot::* const &)(void),_Alloc>(_Fty,_Alloc)' being compiled
1>          with
1>          [
1>              _Ret=int,
1>              _V0_t=Zot *,
1>              _Fret=int,
1>              _Alloc=std::allocator<std::_Func_class<int,Zot *>>,
1>              _Fty=int (__thiscall Zot::* const &)(void)
1>          ]
1>          vc\include\functional(515) : see reference to function template instantiation 'void std::_Func_class<_Ret,_V0_t>::_Do_alloc<_Myimpl,_Fret(__thiscall Zot::* const &)(void),_Alloc>(_Fty,_Alloc)' being compiled
1>          with
1>          [
1>              _Ret=int,
1>              _V0_t=Zot *,
1>              _Fret=int,
1>              _Alloc=std::allocator<std::_Func_class<int,Zot *>>,
1>              _Fty=int (__thiscall Zot::* const &)(void)
1>          ]
1>          vc\include\functional(515) : see reference to function template instantiation 'void std::_Func_class<_Ret,_V0_t>::_Reset_alloc<_Fret,Zot,std::allocator<_Ty>>(_Fret (__thiscall Zot::* const )(void),_Alloc)' being compiled
1>          with
1>          [
1>              _Ret=int,
1>              _V0_t=Zot *,
1>              _Fret=int,
1>              _Ty=std::_Func_class<int,Zot *>,
1>              _Alloc=std::allocator<std::_Func_class<int,Zot *>>
1>          ]
1>          vc\include\functional(515) : see reference to function template instantiation 'void std::_Func_class<_Ret,_V0_t>::_Reset_alloc<_Fret,Zot,std::allocator<_Ty>>(_Fret (__thiscall Zot::* const )(void),_Alloc)' being compiled
1>          with
1>          [
1>              _Ret=int,
1>              _V0_t=Zot *,
1>              _Fret=int,
1>              _Ty=std::_Func_class<int,Zot *>,
1>              _Alloc=std::allocator<std::_Func_class<int,Zot *>>
1>          ]
1>          vc\include\functional(675) : see reference to function template instantiation 'void std::_Func_class<_Ret,_V0_t>::_Reset<int,Zot>(_Fret (__thiscall Zot::* const )(void))' being compiled
1>          with
1>          [
1>              _Ret=int,
1>              _V0_t=Zot *,
1>              _Fret=int
1>          ]
1>          vc\include\functional(675) : see reference to function template instantiation 'void std::_Func_class<_Ret,_V0_t>::_Reset<int,Zot>(_Fret (__thiscall Zot::* const )(void))' being compiled
1>          with
1>          [
1>              _Ret=int,
1>              _V0_t=Zot *,
1>              _Fret=int
1>          ]
1>          c:\..\cxx11.cpp(17) : see reference to function template instantiation 'std::function<_Fty>::function<int(__thiscall Zot::* )(void)>(_Fx &&)' being compiled
1>          with
1>          [
1>              _Fty=int (Zot *),
1>              _Fx=int (__thiscall Zot::* )(void)
1>          ]
1>          c:\...\cxx11.cpp(17) : see reference to function template instantiation 'std::function<_Fty>::function<int(__thiscall Zot::* )(void)>(_Fx &&)' being compiled
1>          with
1>          [
1>              _Fty=int (Zot *),
1>              _Fx=int (__thiscall Zot::* )(void)
1>          ]

最佳答案

以下语法有效并且至少更短:

std::function<int (Zot*)> fn = std::mem_fn(&Zot::A);

关于c++ - std::function 绑定(bind)到成员函数，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/12145035/