std :: bind是否一般使用只移动类型，特别是std :: unique_ptr？ [英] Does std::bind work with move-only types in general, and std::unique_ptr in particular?
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问题描述
我想要使用boost :: asio并尝试编译以下代码：
std :: unique_ptr< buffer_t> buffer = buffers.pop（）;
std :: function< void（const boost :: system :: error_code& size_t）> t = std :: bind（& tcp_client :: handle_read_done，
this，
std :: placeholders :: _ 1，
std :: placeholders :: _ 2，
std： ：move（buffer））;
如果我排除std :: move（buffer），一切都很好，当然从签名
当试图将它传递给boost :: asio :: async_read_some时，它会引发对象上隐式删除的函数从std :: bind返回，对tuple上的删除函数，我假设是因为可移动性，以及很多boost具体错误。如果我只是试图将其分配到一个std ::函数，它应该匹配boost调用的签名，我得到那些相同的元组错误，所以我猜他们是相同的。只要将std :: bind的结果赋给auto就不会产生编译器错误，但是当然我不能调用任何东西。
我做错了什么？下面是试图分配 std :: function< void（const boost :: system :: error_code&，size_t）>
$ b
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2 /../../../../ include /c++/4.6.2/functional：在静态成员函数'static void std :: _ Function_handler
/ home / max / dev / rcon / src / net / tcp_client.cpp：98：34：从这里实例化
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/ c ++ / 4.6.2 / functional：1778：2：错误：没有匹配调用'（std :: _ Bind< std :: _ Mem_fn< void（rcon :: net :: tcp_client :: *） :: error_code& long，unsigned int，std :: unique_ptr< std :: array< unsigned char，10240ul> >）>（rcon :: net :: tcp_client *，std :: _ Placeholder< 1>，std :: _ Placeholder< 2>，std :: unique_ptr< std :: array< unsigned char，10240ul> ;）（const boost :: system :: error_code& long，unsigned int）'
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../ ../include/c++/4.6.2/functional:1130:11：注意：候选人是：
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../ .. /../../include/c++/4.6.2/functional:1201:2：note：template< class ... _Args，class _Result> _Result std :: _Bind< _Functor（_Bound_args ...）> :: operator（）（_Args&& ...）[with _Args = {_Args ...}，_Result = _Result，_Functor = std :: _ Mem_fn< ; void（rcon :: net :: tcp_client :: *）（const boost :: system :: error_code& long unsigned int，std :: unique_ptr< std :: array< unsigned char，10240ul& _Bound_args = {rcon :: net :: tcp_client *，std :: _ Placeholder< 1>，std :: _ Placeholder< 2>，std :: unique_ptr< std :: array< unsigned char，10240ul> >}]
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/functional:1215 ：2：note：template< class ... _Args，class _Result> _Result std :: _ Bind< _Functor（_Bound_args ...）> :: operator（）（_ Args& ...）const [with _Args = {_Args ...}，_Result = _Result，_Functor = std :: _Mem_fn< void（rcon :: net :: tcp_client :: *）（const boost :: system :: error_code& long unsigned int，std :: unique_ptr< std :: array< unsigned char，10240ul> ，_Bound_args = {rcon :: net :: tcp_client *，std :: _占位符<1>，std :: _占位符<2>，std :: unique_ptr< std :: array< unsigned char，10240ul> >}]
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/functional:1229 ：2：note：template< class ... _Args，class _Result> _Result std :: _ Bind< _Functor（_Bound_args ...）> :: operator（）（_ Args& ...）volatile [with _Args = {_Args ...}，_Result = _Result，_Functor = std :: _Mem_fn< void（rcon :: net :: tcp_client :: *）（const boost :: system :: error_code& long unsigned int，std :: unique_ptr< std :: array< unsigned char，10240ul> ，_Bound_args = {rcon :: net :: tcp_client *，std :: _占位符<1>，std :: _占位符<2>，std :: unique_ptr< std :: array< unsigned char，10240ul> >}]
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/functional:1243 ：2：note：template< class ... _Args，class _Result> _Result std :: _ Bind< _Functor（_Bound_args ...）> :: operator（）（_Args& ...）const volatile [with _Args = {_Args ...}，_Result = _Result，_Functor = std： ：_Mem_fn< void（rcon :: net :: tcp_client :: *）（const boost :: system :: error_code& long unsigned int，std :: unique_ptr< std :: array< unsigned char，10240ul> ;，_Bound_args = {rcon :: net :: tcp_client *，std :: _占位符<1>，std :: _占位符<2>，std :: unique_ptr< std :: array< unsigned char，10240ul> >}]
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/functional：In静态成员函数'static void std :: _ Function_base :: _ Base_manager< _Functor> :: _ M_clone（std :: _ Any_data& const std :: _ Any_data& std :: false_type）[with _Functor = std :: _ Bind& _Mem_fn< void（rcon :: net :: tcp_client :: *）（const boost :: system :: error_code& long unsigned int，std :: unique_ptr< std :: array< unsigned char，10240ul> （rcon :: net :: tcp_client *，std :: _ Placeholder< 1>，std :: _ Placeholder< 2>，std :: unique_ptr< std :: array< unsigned char，10240ul>>）>，std :: false_type = std :: integral_constant< bool，false>]'：
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include /c++/4.6.2/functional:1652:8：从'static bool std :: _ Function_base :: _ Base_manager< _Functor> :: _ M_manager（std :: _ Any_data& const std :: _ Any_data& std :: _ Manager_operation） [with _Functor = std :: _ Bind< std :: _ Mem_fn< void（rcon :: net :: tcp_client :: *）（const boost :: system :: error_code& long unsigned int，std :: unique_ptr< std :: array< unsigned char，10240ul> >）>（rcon :: net :: tcp_client *，std :: _ Placeholder< 1>，std :: _ Placeholder< 2>，std :: unique_ptr< std :: array< unsigned char，10240ul> ;]'
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/functional:2149： 6：从'std :: function< _Res（_ArgTypes ...）>实例化:: function（_Functor，typename std :: enable_if<（！std :: is_integral< _Functor> :: value），std :: function< _Res（_ArgTypes ...）> :: _ Useless> :: type）[with _Functor = std :: _ Bind< std :: _ Mem_fn< void（rcon :: net :: tcp_client :: *） :: error_code& long unsigned int，std :: unique_ptr< std :: array< unsigned char，10240ul>>）>（rcon :: net :: tcp_client *，std :: _ Placeholder< 1>，std :: _Placeholder< 2>，std :: unique_ptr< std :: array< unsigned char，10240ul>）> ;, _Res = void，_ArgTypes = {const boost :: system :: error_code& long unsigned int}，typename std :: enable_if<（！std :: is_integral< _Functor> :: value），std :: function< _Res（_ArgTypes ...）> :: _ Useless> :: type = std :: function< void ：system :: error_code& long unsigned int）> :: _ Useless]'
/home/max/dev/rcon/src/net/tcp_client.cpp:98:34：从这里实例化
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/functional:1616:4：错误：使用删除函数'std :: _Bind< _Functor（_Bound_args ...）> :: _Bind（const std :: _Bind< _Functor（_Bound_args ...）&）&）[with _Functor = std :: _ Mem_fn < :: net :: tcp_client :: *）（const boost :: system :: error_code& long unsigned int，std :: unique_ptr< std :: array< unsigned char，10240ul> >）>，_Bound_args = {rcon :: net :: tcp_client *，std :: _ Placeholder< 1>，std :: _ Placeholder< 2> ;, std :: unique_ptr< std :: array< unsigned char，10240ul> >}，std :: _ Bind< _Functor（_Bound_args ...）> = std :: _ Bind< std :: _ Mem_fn< void（rcon :: net :: tcp_client :: *）（const boost :: system :: error_code& long unsigned int，std :: unique_ptr< std :: array< char，10240ul>）>（rcon :: net :: tcp_client *，std :: _ Placeholder< 1>，std :: _ Placeholder< 2>，std :: unique_ptr< std :: array< unsigned char，10240ul> >）>]'
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/功能：1189：7：错误：'std :: _ Bind< _Functor（_Bound_args ...）> :: _ Bind（const std :: _ Bind< _Functor（_Bound_args ...）&） :: _ Mem_fn< void（rcon :: net :: tcp_client :: *）（const boost :: system :: error_code& long unsigned int，std :: unique_ptr< std :: array< unsigned char，10240ul> >，_Bound_args = {rcon :: net :: tcp_client *，std :: _ placeholder< 1>，std :: _ Placeholder< 2>，std :: unique_ptr< std :: array< unsigned char，10240ul> >}，std :: _ Bind< _Functor（_Bound_args ...）> = std :: _ Bind< std :: _ Mem_fn< void（rcon :: net :: tcp_client :: *）（const boost :: system :: error_code& long unsigned int，std :: unique_ptr< std :: array< unsigned char，10240ul>）>（rcon :: net :: tcp_client *，std :: _ Placeholder< 1>，std :: _ Placeholder< 2>，std :: unique_ptr< std :: array< unsigned char，10240ul> >）>]'被隐式删除，因为默认定义将是错误的：
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../。 ./../include/c++/4.6.2/functional:1189:7：错误：使用删除的函数'constexpr std :: tuple< < template-parameter-1-1> > :: tuple（const std :: tuple<< template-parameter-1-1>&）[with _Elements = {rcon :: net :: tcp_client *，std :: _ Placeholder< 1>，std :: _占位符< 2>，std :: unique_ptr< std :: array< unsigned char，10240ul> >}，std :: tuple< < template-parameter-1-1> > = std :: tuple ，std :: _占位符<2>，std :: unique_ptr< std :: array< unsigned char，10240ul> > >]'
在/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2中包含的文件中/ functional：56：0，
从/home/max/dev/rcon/include/net/tcp_client.hpp:4，
从/ home / max / dev / rcon / src / net / tcp_client .cpp：1：
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/tuple： 249：17：error：'constexpr std :: tuple< < template-parameter-1-1> > :: tuple（const std :: tuple<< template-parameter-1-1>&）[with _Elements = {rcon :: net :: tcp_client *，std :: _ Placeholder< 1>，std :: _占位符< 2>，std :: unique_ptr< std :: array< unsigned char，10240ul> >}，std :: tuple< < template-parameter-1-1> > = std :: tuple ，std :: _占位符<2>，std :: unique_ptr< std :: array< unsigned char，10240ul> > >]'被隐式删除，因为默认定义将是错误的：
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../。 ./include/c++/4.6.2/tuple:249:17：错误：使用删除的函数'constexpr std :: _ Tuple_impl <_Idx，_Head，_Tail ...> :: _ Tuple_impl（const std :: _ Tuple_impl< _Idx ，_Head，_Tail ...>&）[with long unsigned int _Idx = 0ul，_Head = rcon :: net :: tcp_client *，_Tail = {std :: _ Placeholder< 1>，std :: _ Placeholder& ，std :: unique_ptr< std :: array< unsigned char，10240ul> >}，std :: _Tuple_impl< _Idx，_Head，_Tail ...> = std :: _Tuple_impl <0ul，rcon :: net :: tcp_client *，std :: _占位符<1>，std :: _占位符<2>，std :: unique_ptr< std :: array< unsigned char，10240ul> > >]'
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/tuple:170 ：17：error：'constexpr std :: _Tuple_impl <_Idx，_Head，_Tail ...> :: _ Tuple_impl（const std :: _Tuple_impl< _Idx，_Head，_Tail ...>&）[with long unsigned int _Idx = 0ul，_Head = rcon :: net :: tcp_client *，_Tail = {std :: _占位符<1>，std :: _占位符<2>，std :: unique_ptr< std :: array< unsigned char，10240ul> >}，std :: _ Tuple_impl< _Idx，_Head，_Tail ...> = std :: _Tuple_impl <0ul，rcon :: net :: tcp_client *，std :: _占位符<1>，std :: _占位符<2>，std :: unique_ptr< std :: array< unsigned char，10240ul> > >]'被隐式删除，因为默认定义将是错误的：
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../。 ./include/c++/4.6.2/tuple:170:17：error：使用删除的函数'constexpr std :: _ Tuple_impl< _Idx，_Head，_Tail ...> :: _ Tuple_impl（const std :: _ Tuple_impl< _Idx ，_Head，_Tail ...>&）[with long unsigned int _Idx = 1ul，_Head = std :: _占位符< 1>，_Tail = {std :: _ Placeholder< 2>，std :: unique_ptr< std :: array< unsigned char，10240ul> >}，std :: _Tuple_impl< _Idx，_Head，_Tail ...> = std :: _Tuple_impl <1ul，std :: _占位符<1>，std :: _占位符<2>，std :: unique_ptr< std :: array< unsigned char，10240ul> > >]'
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/tuple:170 ：17：error：'constexpr std :: _Tuple_impl <_Idx，_Head，_Tail ...> :: _ Tuple_impl（const std :: _Tuple_impl< _Idx，_Head，_Tail ...& _Idx = 1ul，_Head = std :: _占位符<1>，_Tail = {std :: _占位符<2>，std :: unique_ptr< std :: array< unsigned char，10240ul> >}，std :: _Tuple_impl< _Idx，_Head，_Tail ...> = std :: _Tuple_impl <1ul，std :: _占位符<1>，std :: _占位符<2>，std :: unique_ptr< std :: array< unsigned char，10240ul> > >]'被隐式删除，因为默认定义将是错误的：
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../。 ./include/c++/4.6.2/tuple:170:17：错误：使用删除的函数'constexpr std :: _ Tuple_impl <_Idx，_Head，_Tail ...> :: _ Tuple_impl（const std :: _ Tuple_impl< _Idx ，_Head，_Tail ...>&）[with long unsigned int _Idx = 2ul，_Head = std :: _占位符< 2> ;, _Tail = {std :: unique_ptr< std :: array< unsigned char，10240ul> >}，std :: _Tuple_impl< _Idx，_Head，_Tail ...> = std :: _Tuple_impl< 2ul，std :: _占位符< 2>，std :: unique_ptr< std :: array< unsigned char，10240ul> > >]'
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/tuple:170 ：17：error：'constexpr std :: _Tuple_impl <_Idx，_Head，_Tail ...> :: _ Tuple_impl（const std :: _Tuple_impl< _Idx，_Head，_Tail ...& _Idx = 2ul，_Head = std :: _占位符< 2>，_Tail = {std :: unique_ptr< std :: array< unsigned char，10240ul> >}，std :: _Tuple_impl< _Idx，_Head，_Tail ...> = std :: _Tuple_impl< 2ul，std :: _占位符< 2>，std :: unique_ptr< std :: array< unsigned char，10240ul> > >]'被隐式删除，因为默认定义将是错误的：
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../。 ./include/c++/4.6.2/tuple:170:17：error：使用删除的函数'constexpr std :: _ Tuple_impl< _Idx，_Head，_Tail ...> :: _ Tuple_impl（const std :: _ Tuple_impl< _Idx ，_Head，_Tail ...>&）[with long unsigned int _Idx = 3ul，_Head = std :: unique_ptr< std :: array< unsigned char，10240ul> >，_Tail = {}，std :: _Tuple_impl< _Idx，_Head，_Tail ...> = std :: _Tuple_impl< 3ul，std :: unique_ptr< std :: array< unsigned char，10240ul> > >]'
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/tuple:170 ：17：error：'constexpr std :: _Tuple_impl <_Idx，_Head，_Tail ...> :: _ Tuple_impl（const std :: _Tuple_impl< _Idx，_Head，_Tail ...>&）[with long unsigned int _Idx = 3ul，_Head = std :: unique_ptr< std :: array< unsigned char，10240ul> >，_Tail = {}，std :: _Tuple_impl< _Idx，_Head，_Tail ...> = std :: _Tuple_impl< 3ul，std :: unique_ptr< std :: array< unsigned char，10240ul> > >]'被隐式删除，因为默认定义将是错误的：
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../。 ./include/c++/4.6.2/tuple:170:17：error：使用删除的函数'std :: _ Head_base< 3ul，std :: unique_ptr< std :: array< unsigned char，10240ul> >，false> :: _ Head_base（const std :: _ Head_base< 3ul，std :: unique_ptr< std :: array< unsigned char，10240ul> ;,>&）'
/ usr / gcc / x86_64-unknown-linux-gnu / 4.6.2 /../../../../ include / c ++ / 4.6.2 / tuple：91：12：error：'std :: _ Head_base <3ul， std :: unique_ptr< std :: array< unsigned char，10240ul> >，false> :: _ Head_base（const std :: _ Head_base< 3ul，std :: unique_ptr< std :: array< unsigned char，10240ul>>，false>&）'被隐含地删除，因为默认定义将是错误：
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/tuple:91 ：12：错误：使用已删除的函数'std :: unique_ptr< _Tp，_Dp> :: unique_ptr（const std :: unique_ptr< _Tp，_Dp>&）[with _Tp = std :: array< unsigned char，10240ul> ，_Dp = std :: default_delete< std :: array< unsigned char，10240ul> >，std :: unique_ptr< _Tp，_Dp> = std :: unique_ptr< std :: array< unsigned char，10240ul> >]'
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/bits/unique_ptr .h：256：7：错误：在此声明
更新：
我知道上面似乎不工作。但是，那么，应该不是下面的工作呢？
std :: unique_ptr< buffer_t> buffer = buffers.pop（）;
auto t = std :: bind（& tcp_client :: handle_read_done，
this，
std :: placeholders :: _ 1，
std :: placeholder： ：_2，
std :: move（buffer））;
size_t var = 10;
boost :: system :: error_code code;
t（code，var）;
handle_read_done 的签名
void tcp_client :: handle_read_done（const boost :: system :: error_code& error，size_t bytes_read，std :: unique_ptr< buffer_t>缓冲区）
感觉我缺少很明显的东西。
错误讯息：
/ home / max / dev / rcon /src/net/tcp_client.cpp：在成员函数'void rcon :: net :: tcp_client :: handle_connect_done（const boost :: system :: error_code& const string&）'：
/ home / max / dev / rcon / src / net / tcp_client.cpp：101：15：错误：无匹配调用'（std :: _ Bind< std :: _ Mem_fn< void（rcon :: net :: tcp_client :: *） boost :: system :: error_code& long，long unsigned int，std :: unique_ptr< std :: array< unsigned char，10240ul>>）>（rcon :: net :: tcp_client *，std :: _ Placeholder< 1> ，std :: _ Placeholder< 2>，std :: unique_ptr< std :: array< unsigned char，10240ul>>）>）（boost :: system :: error_code& size_t&）'
/ usr /lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/functional:1130:11：注：候选人是：
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/functional:1201:2：note：template< ; class ... _Args，class _Result> _Result std :: _Bind< _Functor（_Bound_args ...）> :: operator（）（_Args&& ...）[with _Args = {_Args ...}，_Result = _Result，_Functor = std :: _ Mem_fn< ; void（rcon :: net :: tcp_client :: *）（const boost :: system :: error_code& long unsigned int，std :: unique_ptr< std :: array< unsigned char，10240ul& _Bound_args = {rcon :: net :: tcp_client *，std :: _ Placeholder< 1>，std :: _ Placeholder< 2>，std :: unique_ptr< std :: array< unsigned char，10240ul> >}]
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/functional:1215 ：2：note：template< class ... _Args，class _Result> _Result std :: _ Bind< _Functor（_Bound_args ...）> :: operator（）（_ Args& ...）const [with _Args = {_Args ...}，_Result = _Result，_Functor = std :: _Mem_fn< void（rcon :: net :: tcp_client :: *）（const boost :: system :: error_code& long unsigned int，std :: unique_ptr< std :: array< unsigned char，10240ul> ，_Bound_args = {rcon :: net :: tcp_client *，std :: _占位符<1>，std :: _占位符<2>，std :: unique_ptr< std :: array< unsigned char，10240ul> >}]
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/functional:1229 ：2：note：template< class ... _Args，class _Result> _Result std :: _ Bind< _Functor（_Bound_args ...）> :: operator（）（_ Args& ...）volatile [with _Args = {_Args ...}，_Result = _Result，_Functor = std :: _Mem_fn< void（rcon :: net :: tcp_client :: *）（const boost :: system :: error_code& long unsigned int，std :: unique_ptr< std :: array< unsigned char，10240ul> ，_Bound_args = {rcon :: net :: tcp_client *，std :: _占位符<1>，std :: _占位符<2>，std :: unique_ptr< std :: array< unsigned char，10240ul> >}]
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/functional:1243 ：2：note：template< class ... _Args，class _Result> _Result std :: _ Bind< _Functor（_Bound_args ...）> :: operator（）（_Args& ...）const volatile [with _Args = {_Args ...}，_Result = _Result，_Functor = std： ：_Mem_fn< void（rcon :: net :: tcp_client :: *）（const boost :: system :: error_code& long unsigned int，std :: unique_ptr< std :: array< unsigned char，10240ul> ;，_Bound_args = {rcon :: net :: tcp_client *，std :: _占位符<1>，std :: _占位符<2>，std :: unique_ptr< std :: array< unsigned char，10240ul> >}]
解决方案
std :: bind 在只移动类型下运行良好。然而，它在过程中创建一个只移动函数。 std :: function 需要一个可构造的复制函子。这听起来像 boost :: asio 也。
当你调用只移动 bind 函数，它将其绑定参数作为lvalues传递给目标操作符（）。因此，如果你的一个绑定参数是move-only，目标operator（）必须采用该参数（可能const）lvalue引用。
I'm trying to use boost::asio and run into a bit of a quagmire.
I'm trying to compile the following code:
std::unique_ptr<buffer_t> buffer = buffers.pop();
std::function<void(const boost::system::error_code&, size_t)> t = std::bind(&tcp_client::handle_read_done,
this,
std::placeholders::_1,
std::placeholders::_2,
std::move(buffer));
Everything works fine if I exclude the std::move(buffer), of course from both the signature of handle_read_done and as a passed argument in std::bind.
When trying to pass it into boost::asio::async_read_some it complains of implicitly deleted functions on the object returned from std::bind, on deleted functions on tuple which I assume are because of the movability, as well as a lot of boost specific errors. If I just try to assign it into a std::function which should match the signature that boost calls, I get those same tuple errors, so I guess they are the same ones. Just assigning the result of std::bind to auto yields no compiler error, but of course I can't call anything on it.
What am I doing wrong? Below is the output from when trying to assign to std::function<void(const boost::system::error_code&,size_t)>
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/functional: In static member function ‘static void std::_Function_handler<void(_ArgTypes ...), _Functor>::_M_invoke(const std::_Any_data&, _ArgTypes ...) [with _Functor = std::_Bind<std::_Mem_fn<void (rcon::net::tcp_client::*)(const boost::system::error_code&, long unsigned int, std::unique_ptr<std::array<unsigned char, 10240ul> >)>(rcon::net::tcp_client*, std::_Placeholder<1>, std::_Placeholder<2>, std::unique_ptr<std::array<unsigned char, 10240ul> >)>, _ArgTypes = {const boost::system::error_code&, long unsigned int}]’:
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/functional:2148:6: instantiated from ‘std::function<_Res(_ArgTypes ...)>::function(_Functor, typename std::enable_if<(! std::is_integral<_Functor>::value), std::function<_Res(_ArgTypes ...)>::_Useless>::type) [with _Functor = std::_Bind<std::_Mem_fn<void (rcon::net::tcp_client::*)(const boost::system::error_code&, long unsigned int, std::unique_ptr<std::array<unsigned char, 10240ul> >)>(rcon::net::tcp_client*, std::_Placeholder<1>, std::_Placeholder<2>, std::unique_ptr<std::array<unsigned char, 10240ul> >)>, _Res = void, _ArgTypes = {const boost::system::error_code&, long unsigned int}, typename std::enable_if<(! std::is_integral<_Functor>::value), std::function<_Res(_ArgTypes ...)>::_Useless>::type = std::function<void(const boost::system::error_code&, long unsigned int)>::_Useless]’
/home/max/dev/rcon/src/net/tcp_client.cpp:98:34: instantiated from here
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/functional:1778:2: error: no match for call to ‘(std::_Bind<std::_Mem_fn<void (rcon::net::tcp_client::*)(const boost::system::error_code&, long unsigned int, std::unique_ptr<std::array<unsigned char, 10240ul> >)>(rcon::net::tcp_client*, std::_Placeholder<1>, std::_Placeholder<2>, std::unique_ptr<std::array<unsigned char, 10240ul> >)>) (const boost::system::error_code&, long unsigned int)’
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/functional:1130:11: note: candidates are:
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/functional:1201:2: note: template<class ... _Args, class _Result> _Result std::_Bind<_Functor(_Bound_args ...)>::operator()(_Args&& ...) [with _Args = {_Args ...}, _Result = _Result, _Functor = std::_Mem_fn<void (rcon::net::tcp_client::*)(const boost::system::error_code&, long unsigned int, std::unique_ptr<std::array<unsigned char, 10240ul> >)>, _Bound_args = {rcon::net::tcp_client*, std::_Placeholder<1>, std::_Placeholder<2>, std::unique_ptr<std::array<unsigned char, 10240ul> >}]
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/functional:1215:2: note: template<class ... _Args, class _Result> _Result std::_Bind<_Functor(_Bound_args ...)>::operator()(_Args&& ...) const [with _Args = {_Args ...}, _Result = _Result, _Functor = std::_Mem_fn<void (rcon::net::tcp_client::*)(const boost::system::error_code&, long unsigned int, std::unique_ptr<std::array<unsigned char, 10240ul> >)>, _Bound_args = {rcon::net::tcp_client*, std::_Placeholder<1>, std::_Placeholder<2>, std::unique_ptr<std::array<unsigned char, 10240ul> >}]
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/functional:1229:2: note: template<class ... _Args, class _Result> _Result std::_Bind<_Functor(_Bound_args ...)>::operator()(_Args&& ...) volatile [with _Args = {_Args ...}, _Result = _Result, _Functor = std::_Mem_fn<void (rcon::net::tcp_client::*)(const boost::system::error_code&, long unsigned int, std::unique_ptr<std::array<unsigned char, 10240ul> >)>, _Bound_args = {rcon::net::tcp_client*, std::_Placeholder<1>, std::_Placeholder<2>, std::unique_ptr<std::array<unsigned char, 10240ul> >}]
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/functional:1243:2: note: template<class ... _Args, class _Result> _Result std::_Bind<_Functor(_Bound_args ...)>::operator()(_Args&& ...) const volatile [with _Args = {_Args ...}, _Result = _Result, _Functor = std::_Mem_fn<void (rcon::net::tcp_client::*)(const boost::system::error_code&, long unsigned int, std::unique_ptr<std::array<unsigned char, 10240ul> >)>, _Bound_args = {rcon::net::tcp_client*, std::_Placeholder<1>, std::_Placeholder<2>, std::unique_ptr<std::array<unsigned char, 10240ul> >}]
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/functional: In static member function ‘static void std::_Function_base::_Base_manager<_Functor>::_M_clone(std::_Any_data&, const std::_Any_data&, std::false_type) [with _Functor = std::_Bind<std::_Mem_fn<void (rcon::net::tcp_client::*)(const boost::system::error_code&, long unsigned int, std::unique_ptr<std::array<unsigned char, 10240ul> >)>(rcon::net::tcp_client*, std::_Placeholder<1>, std::_Placeholder<2>, std::unique_ptr<std::array<unsigned char, 10240ul> >)>, std::false_type = std::integral_constant<bool, false>]’:
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/functional:1652:8: instantiated from ‘static bool std::_Function_base::_Base_manager<_Functor>::_M_manager(std::_Any_data&, const std::_Any_data&, std::_Manager_operation) [with _Functor = std::_Bind<std::_Mem_fn<void (rcon::net::tcp_client::*)(const boost::system::error_code&, long unsigned int, std::unique_ptr<std::array<unsigned char, 10240ul> >)>(rcon::net::tcp_client*, std::_Placeholder<1>, std::_Placeholder<2>, std::unique_ptr<std::array<unsigned char, 10240ul> >)>]’
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/functional:2149:6: instantiated from ‘std::function<_Res(_ArgTypes ...)>::function(_Functor, typename std::enable_if<(! std::is_integral<_Functor>::value), std::function<_Res(_ArgTypes ...)>::_Useless>::type) [with _Functor = std::_Bind<std::_Mem_fn<void (rcon::net::tcp_client::*)(const boost::system::error_code&, long unsigned int, std::unique_ptr<std::array<unsigned char, 10240ul> >)>(rcon::net::tcp_client*, std::_Placeholder<1>, std::_Placeholder<2>, std::unique_ptr<std::array<unsigned char, 10240ul> >)>, _Res = void, _ArgTypes = {const boost::system::error_code&, long unsigned int}, typename std::enable_if<(! std::is_integral<_Functor>::value), std::function<_Res(_ArgTypes ...)>::_Useless>::type = std::function<void(const boost::system::error_code&, long unsigned int)>::_Useless]’
/home/max/dev/rcon/src/net/tcp_client.cpp:98:34: instantiated from here
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/functional:1616:4: error: use of deleted function ‘std::_Bind<_Functor(_Bound_args ...)>::_Bind(const std::_Bind<_Functor(_Bound_args ...)>&) [with _Functor = std::_Mem_fn<void (rcon::net::tcp_client::*)(const boost::system::error_code&, long unsigned int, std::unique_ptr<std::array<unsigned char, 10240ul> >)>, _Bound_args = {rcon::net::tcp_client*, std::_Placeholder<1>, std::_Placeholder<2>, std::unique_ptr<std::array<unsigned char, 10240ul> >}, std::_Bind<_Functor(_Bound_args ...)> = std::_Bind<std::_Mem_fn<void (rcon::net::tcp_client::*)(const boost::system::error_code&, long unsigned int, std::unique_ptr<std::array<unsigned char, 10240ul> >)>(rcon::net::tcp_client*, std::_Placeholder<1>, std::_Placeholder<2>, std::unique_ptr<std::array<unsigned char, 10240ul> >)>]’
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/functional:1189:7: error: ‘std::_Bind<_Functor(_Bound_args ...)>::_Bind(const std::_Bind<_Functor(_Bound_args ...)>&) [with _Functor = std::_Mem_fn<void (rcon::net::tcp_client::*)(const boost::system::error_code&, long unsigned int, std::unique_ptr<std::array<unsigned char, 10240ul> >)>, _Bound_args = {rcon::net::tcp_client*, std::_Placeholder<1>, std::_Placeholder<2>, std::unique_ptr<std::array<unsigned char, 10240ul> >}, std::_Bind<_Functor(_Bound_args ...)> = std::_Bind<std::_Mem_fn<void (rcon::net::tcp_client::*)(const boost::system::error_code&, long unsigned int, std::unique_ptr<std::array<unsigned char, 10240ul> >)>(rcon::net::tcp_client*, std::_Placeholder<1>, std::_Placeholder<2>, std::unique_ptr<std::array<unsigned char, 10240ul> >)>]’ is implicitly deleted because the default definition would be ill-formed:
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/functional:1189:7: error: use of deleted function ‘constexpr std::tuple< <template-parameter-1-1> >::tuple(const std::tuple< <template-parameter-1-1> >&) [with _Elements = {rcon::net::tcp_client*, std::_Placeholder<1>, std::_Placeholder<2>, std::unique_ptr<std::array<unsigned char, 10240ul> >}, std::tuple< <template-parameter-1-1> > = std::tuple<rcon::net::tcp_client*, std::_Placeholder<1>, std::_Placeholder<2>, std::unique_ptr<std::array<unsigned char, 10240ul> > >]’
In file included from /usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/functional:56:0,
from /home/max/dev/rcon/include/net/tcp_client.hpp:4,
from /home/max/dev/rcon/src/net/tcp_client.cpp:1:
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/tuple:249:17: error: ‘constexpr std::tuple< <template-parameter-1-1> >::tuple(const std::tuple< <template-parameter-1-1> >&) [with _Elements = {rcon::net::tcp_client*, std::_Placeholder<1>, std::_Placeholder<2>, std::unique_ptr<std::array<unsigned char, 10240ul> >}, std::tuple< <template-parameter-1-1> > = std::tuple<rcon::net::tcp_client*, std::_Placeholder<1>, std::_Placeholder<2>, std::unique_ptr<std::array<unsigned char, 10240ul> > >]’ is implicitly deleted because the default definition would be ill-formed:
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/tuple:249:17: error: use of deleted function ‘constexpr std::_Tuple_impl<_Idx, _Head, _Tail ...>::_Tuple_impl(const std::_Tuple_impl<_Idx, _Head, _Tail ...>&) [with long unsigned int _Idx = 0ul, _Head = rcon::net::tcp_client*, _Tail = {std::_Placeholder<1>, std::_Placeholder<2>, std::unique_ptr<std::array<unsigned char, 10240ul> >}, std::_Tuple_impl<_Idx, _Head, _Tail ...> = std::_Tuple_impl<0ul, rcon::net::tcp_client*, std::_Placeholder<1>, std::_Placeholder<2>, std::unique_ptr<std::array<unsigned char, 10240ul> > >]’
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/tuple:170:17: error: ‘constexpr std::_Tuple_impl<_Idx, _Head, _Tail ...>::_Tuple_impl(const std::_Tuple_impl<_Idx, _Head, _Tail ...>&) [with long unsigned int _Idx = 0ul, _Head = rcon::net::tcp_client*, _Tail = {std::_Placeholder<1>, std::_Placeholder<2>, std::unique_ptr<std::array<unsigned char, 10240ul> >}, std::_Tuple_impl<_Idx, _Head, _Tail ...> = std::_Tuple_impl<0ul, rcon::net::tcp_client*, std::_Placeholder<1>, std::_Placeholder<2>, std::unique_ptr<std::array<unsigned char, 10240ul> > >]’ is implicitly deleted because the default definition would be ill-formed:
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/tuple:170:17: error: use of deleted function ‘constexpr std::_Tuple_impl<_Idx, _Head, _Tail ...>::_Tuple_impl(const std::_Tuple_impl<_Idx, _Head, _Tail ...>&) [with long unsigned int _Idx = 1ul, _Head = std::_Placeholder<1>, _Tail = {std::_Placeholder<2>, std::unique_ptr<std::array<unsigned char, 10240ul> >}, std::_Tuple_impl<_Idx, _Head, _Tail ...> = std::_Tuple_impl<1ul, std::_Placeholder<1>, std::_Placeholder<2>, std::unique_ptr<std::array<unsigned char, 10240ul> > >]’
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/tuple:170:17: error: ‘constexpr std::_Tuple_impl<_Idx, _Head, _Tail ...>::_Tuple_impl(const std::_Tuple_impl<_Idx, _Head, _Tail ...>&) [with long unsigned int _Idx = 1ul, _Head = std::_Placeholder<1>, _Tail = {std::_Placeholder<2>, std::unique_ptr<std::array<unsigned char, 10240ul> >}, std::_Tuple_impl<_Idx, _Head, _Tail ...> = std::_Tuple_impl<1ul, std::_Placeholder<1>, std::_Placeholder<2>, std::unique_ptr<std::array<unsigned char, 10240ul> > >]’ is implicitly deleted because the default definition would be ill-formed:
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/tuple:170:17: error: use of deleted function ‘constexpr std::_Tuple_impl<_Idx, _Head, _Tail ...>::_Tuple_impl(const std::_Tuple_impl<_Idx, _Head, _Tail ...>&) [with long unsigned int _Idx = 2ul, _Head = std::_Placeholder<2>, _Tail = {std::unique_ptr<std::array<unsigned char, 10240ul> >}, std::_Tuple_impl<_Idx, _Head, _Tail ...> = std::_Tuple_impl<2ul, std::_Placeholder<2>, std::unique_ptr<std::array<unsigned char, 10240ul> > >]’
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/tuple:170:17: error: ‘constexpr std::_Tuple_impl<_Idx, _Head, _Tail ...>::_Tuple_impl(const std::_Tuple_impl<_Idx, _Head, _Tail ...>&) [with long unsigned int _Idx = 2ul, _Head = std::_Placeholder<2>, _Tail = {std::unique_ptr<std::array<unsigned char, 10240ul> >}, std::_Tuple_impl<_Idx, _Head, _Tail ...> = std::_Tuple_impl<2ul, std::_Placeholder<2>, std::unique_ptr<std::array<unsigned char, 10240ul> > >]’ is implicitly deleted because the default definition would be ill-formed:
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/tuple:170:17: error: use of deleted function ‘constexpr std::_Tuple_impl<_Idx, _Head, _Tail ...>::_Tuple_impl(const std::_Tuple_impl<_Idx, _Head, _Tail ...>&) [with long unsigned int _Idx = 3ul, _Head = std::unique_ptr<std::array<unsigned char, 10240ul> >, _Tail = {}, std::_Tuple_impl<_Idx, _Head, _Tail ...> = std::_Tuple_impl<3ul, std::unique_ptr<std::array<unsigned char, 10240ul> > >]’
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/tuple:170:17: error: ‘constexpr std::_Tuple_impl<_Idx, _Head, _Tail ...>::_Tuple_impl(const std::_Tuple_impl<_Idx, _Head, _Tail ...>&) [with long unsigned int _Idx = 3ul, _Head = std::unique_ptr<std::array<unsigned char, 10240ul> >, _Tail = {}, std::_Tuple_impl<_Idx, _Head, _Tail ...> = std::_Tuple_impl<3ul, std::unique_ptr<std::array<unsigned char, 10240ul> > >]’ is implicitly deleted because the default definition would be ill-formed:
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/tuple:170:17: error: use of deleted function ‘std::_Head_base<3ul, std::unique_ptr<std::array<unsigned char, 10240ul> >, false>::_Head_base(const std::_Head_base<3ul, std::unique_ptr<std::array<unsigned char, 10240ul> >, false>&)’
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/tuple:91:12: error: ‘std::_Head_base<3ul, std::unique_ptr<std::array<unsigned char, 10240ul> >, false>::_Head_base(const std::_Head_base<3ul, std::unique_ptr<std::array<unsigned char, 10240ul> >, false>&)’ is implicitly deleted because the default definition would be ill-formed:
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/tuple:91:12: error: use of deleted function ‘std::unique_ptr<_Tp, _Dp>::unique_ptr(const std::unique_ptr<_Tp, _Dp>&) [with _Tp = std::array<unsigned char, 10240ul>, _Dp = std::default_delete<std::array<unsigned char, 10240ul> >, std::unique_ptr<_Tp, _Dp> = std::unique_ptr<std::array<unsigned char, 10240ul> >]’
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/bits/unique_ptr.h:256:7: error: declared here
Update:
I understand that the above doesn't seem to work. But then, shouldn't the following work?
std::unique_ptr<buffer_t> buffer = buffers.pop();
auto t = std::bind(&tcp_client::handle_read_done,
this,
std::placeholders::_1,
std::placeholders::_2,
std::move(buffer));
size_t var = 10;
boost::system::error_code code;
t(code, var);
Where the signature of handle_read_done is
void tcp_client::handle_read_done(const boost::system::error_code & error, size_t bytes_read, std::unique_ptr<buffer_t> buffer)
It feels like I am missing something very obvious.
Error message:
/home/max/dev/rcon/src/net/tcp_client.cpp: In member function ‘void rcon::net::tcp_client::handle_connect_done(const boost::system::error_code&, const string&)’:
/home/max/dev/rcon/src/net/tcp_client.cpp:101:15: error: no match for call to ‘(std::_Bind<std::_Mem_fn<void (rcon::net::tcp_client::*)(const boost::system::error_code&, long unsigned int, std::unique_ptr<std::array<unsigned char, 10240ul> >)>(rcon::net::tcp_client*, std::_Placeholder<1>, std::_Placeholder<2>, std::unique_ptr<std::array<unsigned char, 10240ul> >)>) (boost::system::error_code&, size_t&)’
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/functional:1130:11: note: candidates are:
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/functional:1201:2: note: template<class ... _Args, class _Result> _Result std::_Bind<_Functor(_Bound_args ...)>::operator()(_Args&& ...) [with _Args = {_Args ...}, _Result = _Result, _Functor = std::_Mem_fn<void (rcon::net::tcp_client::*)(const boost::system::error_code&, long unsigned int, std::unique_ptr<std::array<unsigned char, 10240ul> >)>, _Bound_args = {rcon::net::tcp_client*, std::_Placeholder<1>, std::_Placeholder<2>, std::unique_ptr<std::array<unsigned char, 10240ul> >}]
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/functional:1215:2: note: template<class ... _Args, class _Result> _Result std::_Bind<_Functor(_Bound_args ...)>::operator()(_Args&& ...) const [with _Args = {_Args ...}, _Result = _Result, _Functor = std::_Mem_fn<void (rcon::net::tcp_client::*)(const boost::system::error_code&, long unsigned int, std::unique_ptr<std::array<unsigned char, 10240ul> >)>, _Bound_args = {rcon::net::tcp_client*, std::_Placeholder<1>, std::_Placeholder<2>, std::unique_ptr<std::array<unsigned char, 10240ul> >}]
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/functional:1229:2: note: template<class ... _Args, class _Result> _Result std::_Bind<_Functor(_Bound_args ...)>::operator()(_Args&& ...) volatile [with _Args = {_Args ...}, _Result = _Result, _Functor = std::_Mem_fn<void (rcon::net::tcp_client::*)(const boost::system::error_code&, long unsigned int, std::unique_ptr<std::array<unsigned char, 10240ul> >)>, _Bound_args = {rcon::net::tcp_client*, std::_Placeholder<1>, std::_Placeholder<2>, std::unique_ptr<std::array<unsigned char, 10240ul> >}]
/usr/lib/gcc/x86_64-unknown-linux-gnu/4.6.2/../../../../include/c++/4.6.2/functional:1243:2: note: template<class ... _Args, class _Result> _Result std::_Bind<_Functor(_Bound_args ...)>::operator()(_Args&& ...) const volatile [with _Args = {_Args ...}, _Result = _Result, _Functor = std::_Mem_fn<void (rcon::net::tcp_client::*)(const boost::system::error_code&, long unsigned int, std::unique_ptr<std::array<unsigned char, 10240ul> >)>, _Bound_args = {rcon::net::tcp_client*, std::_Placeholder<1>, std::_Placeholder<2>, std::unique_ptr<std::array<unsigned char, 10240ul> >}]
解决方案
std::bind works fine with move-only types. However it creates a move-only functor in the process. std::function requires a copy constructible functor. It sounds like boost::asio does too.
When you call the move-only bind functor, it will pass its bound arguments as lvalues to the target operator(). So if one of your bound arguments is move-only, the target operator() must take that argument by (possibly const) lvalue reference.
这篇关于std :: bind是否一般使用只移动类型，特别是std :: unique_ptr？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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