使用tr1::function时编译错误

Question

其目的是在调用CVS890Executor::do_full_frame中的m_callback_fn时执行CDevVS890。

以下是经定罪的法典：

"CDevVS890.h"
typedef std::tr1::function<void (void* frame, int len)> DoFrameFn; 

class CDevVS890
{
public:
    CDevVS890();

    void receive();   

    DoFrameFn m_callback_fn;
}

"CDevVS890.cpp"
void CDevVS890::receive()
{
    ...
    m_callback_fn((void*)frame, (int)len);
}

/*----------------------------------------------------------------------*/

"CVS890Executor.h"
class CVS890Executor
{
public:
    CVS890Executor();

private:
    void hookup_to_DevVS890();
    void do_full_frame( void* frame, int len );
}

"CVS890Executor.cpp"
CVS890Executor::CVS890Executor()
{
    hookup_to_DevVS890();
}

void CVS890Executor::hookup_to_DevVS890()
{
m_pDevVS890 = new CDevVS890();
m_pDevVS890->m_callback_fn = 
    std::tr1::bind(&CVS890Executor::do_full_frame, this, _1);
}

void CVS890Executor::do_full_frame(void* frame, int len)
{
   ...
} 

这些错误是多重的，很难读懂：

在/usr/lib/gcc/x86_64-redhat-linux/4.4.6/../../../../include/c++/4.4.6/tr1/functional:56，中包含的文件中，来自././src/Common/cdevVS890.h:17，来自CVS890Executor.h:13，来自CVS890Executor.cpp:8:成员函数中的CVS890Executor.cpp:8-typename std::tr1::result_of<_Functor(typename std::tr1::result_of 0)>(_Bound_argsstd::tr1::tuple<_UElements ...>) >：类型.)>：类型std::tr1::_Bind<_Functor(_Bound_args .)>：：__call(const std::tr1::tuple<_UElements ...>&，std::tr1::_Index_tuple<_Indexes ...>)，_Args = void*&，int ..._Indexes = 0，1，_Functor = std::tr1::_Mem_fn，_Bound_args =const 890_Functor*，/usr/lib/gcc/x86_64-redhat-linux/4.4.6/../../../../include/c++/4.4.6/tr1_impl/functional:1191: std::tr1::_Placeholder<1>â:从std::tr1::result_of<_Functor(typename std::tr1::result_of 0)>(_Bound_args，std::tr1::tuple<_UElements ...>)>：类型.)>：类型std::tr1::_Bind<_Functor(_Bound_args .)>：：operator()(_Args&.)使用_Args = void*，int，_Functor = std::tr1::_Mem_fn，_Bound_args =const 890_Functor*，std::tr1::_Placeholder<1>âstd：：tr1：：_Function_handler：：_M_invoke实例化从-静态空洞std::tr1::_Function_handler::_M_invoke(const std::tr1::_Any_data&，_ArgTypes ...)使用_Functor = std::tr1::_Bind(CVS890Executor*，std::tr1::_Placeholder<1>)>，_ArgTypes = void*，int-âstd：：tr1：：function<_Res实例化âstd::tr1::function<_Res(_ArgTypes .)>：function(_Functor，typename __gnu_cxx::__enable_if<(！( std::tr1::is_integral::value)，std::tr1::function<_Res(_ArgTypes .)>：：Useless>：：_type( _Functor =std：：tr1：：_Bind( _Res 890_Functor*，std::tr1::_Placeholder<1>)>，_Res= void，_ArgTypes = void*，int /usr/lib/gcc/x86_64-redhat-linux/4.4.6/../../../../include/c++/4.4.6/tr1_impl/functional:1885:实例化自-！( std::tr1::is_integral::value)，std::tr1::function<_Res(ArgTypes .)>&>：：_type std::tr1::function<_Res(_ArgTypes .)>：：operator=( _Functor ) with _Functor=std：：tr1：：_Bind( _Res 890_Functor*，std::tr1::_Placeholder<1>)>，_Res= void，_ArgTypes = void*，从这里实例化/usr/lib/gcc/x86_64-redhat-linux/4.4.6/../../../../include/c++/4.4.6/tr1_impl/functional:1137: CVS890Executor.cpp:115:不匹配对-(std：：tr1：：_Mem_fn)的调用( call 890 error*&，/usr/lib/gcc/x86_64-redhat-linux/4.4.6/../../../../include/c++/4.4.6/tr1_impl/functional:546:备注:候选人有：_Res std::tr1::_Mem_fn<_Res (_Class::*)(_ArgTypes .)>：：operator()(_Class&，_ArgTypes .)与_Res = void，_Class = CVS890Executor，_ArgTypes = void*，int std::tr1::_Mem_fn<_Res (_Class::*)(_ArgTypes .)>：操作符()(_Class*，_ArgTypes .)与_Res = void，_Class = CVS890Executor，_ArgTypes = void*，int _Class错误:返回一个值的返回语句，在函数中返回'void‘make：* CVS890Executor.o错误1

知道这是怎么回事吗？

干杯

Answer 1

你忘了第二个论点了。您对bind函数的调用应该如下所示：

std::tr1::bind(&CVS890Executor::do_full_frame, this, _1, _2);
//                                                       ^^

Answer 2

在CVS890Executor::hookup_to_DevVS890()中，没有将任何参数绑定到成员函数do_full_frame。

您还试图将函数的返回值赋值给m_callback_fn，但是do_full_frame()被声明为返回void (没有返回值)。