C++ C++；将引用变量传递给g++-4.7.4

当线程启动时，我需要启动一个传递复杂参数（std:：thread）作为参数的线程。我使用的是'std:：ref。这段代码适用于更新的环境（在Ubuntu上运行的g++-4.8.2）

现在，我必须在一个旧的编译器（g++4.7.4）中编译相同的代码，我会遇到错误

代码以及错误如下所示：

ReaderThread.hpp

class ReaderThread {
    void start(Reader reader, SyncController &syncController);
}

void ReaderThread::start(Reader reader, SyncController &syncController)
{

        Do something...
}

int main()
{

    ...do stuff...

    /* 
     * Create and start the reader thread. The created object must live
     * during the whole thread life.
     * std::ref is used to pass as reference
     */
    myReader = ReaderFactory(params);

    std::shared_ptr<ReaderThread> ptr(new ReaderThread); 
    std::thread th(&ReaderThread::start, ptr, myReader, std::ref(syncController));


    ...do other stuff...
}

ReaderThread.cpp

class ReaderThread {
    void start(Reader reader, SyncController &syncController);
}

void ReaderThread::start(Reader reader, SyncController &syncController)
{

        Do something...
}

int main()
{

    ...do stuff...

    /* 
     * Create and start the reader thread. The created object must live
     * during the whole thread life.
     * std::ref is used to pass as reference
     */
    myReader = ReaderFactory(params);

    std::shared_ptr<ReaderThread> ptr(new ReaderThread); 
    std::thread th(&ReaderThread::start, ptr, myReader, std::ref(syncController));


    ...do other stuff...
}

main.cpp

class ReaderThread {
    void start(Reader reader, SyncController &syncController);
}

void ReaderThread::start(Reader reader, SyncController &syncController)
{

        Do something...
}

int main()
{

    ...do stuff...

    /* 
     * Create and start the reader thread. The created object must live
     * during the whole thread life.
     * std::ref is used to pass as reference
     */
    myReader = ReaderFactory(params);

    std::shared_ptr<ReaderThread> ptr(new ReaderThread); 
    std::thread th(&ReaderThread::start, ptr, myReader, std::ref(syncController));


    ...do other stuff...
}

intmain（）
{
…做事。。。
/* 
*创建并启动读卡器线程。创建的对象必须处于活动状态
*在整个线程生命周期中。
*std:：ref用于作为引用传递
*/
myReader=ReaderFactory（参数）；
std:：shared_ptr ptr（新的读线程）；
std:：thread th（&ReaderThread:：start、ptr、myReader、std:：ref（syncController））；
…做其他事情。。。
}

错误：

In file included from /usr/gcc-4.7.4/lib/gcc/i586-pc-linux-gnu/4.7.4/../../../../include/c++/4.7.4/bits/move.h:57:0,
                 from /usr/gcc-4.7.4/lib/gcc/i586-pc-linux-gnu/4.7.4/../../../../include/c++/4.7.4/bits/stl_pair.h:61,
                 from /usr/gcc-4.7.4/lib/gcc/i586-pc-linux-gnu/4.7.4/../../../../include/c++/4.7.4/bits/stl_algobase.h:65,
                 from /usr/gcc-4.7.4/lib/gcc/i586-pc-linux-gnu/4.7.4/../../../../include/c++/4.7.4/bits/char_traits.h:41,
                 from /usr/gcc-4.7.4/lib/gcc/i586-pc-linux-gnu/4.7.4/../../../../include/c++/4.7.4/ios:41,
                 from /usr/gcc-4.7.4/lib/gcc/i586-pc-linux-gnu/4.7.4/../../../../include/c++/4.7.4/ostream:40,
                 from /usr/gcc-4.7.4/lib/gcc/i586-pc-linux-gnu/4.7.4/../../../../include/c++/4.7.4/iostream:40,
                 from ./main.cpp:11:
/usr/gcc-4.7.4/lib/gcc/i586-pc-linux-gnu/4.7.4/../../../../include/c++/4.7.4/type_traits: In instantiation of 'struct std::_Result_of_impl<false, false, std::_Mem_fn<void (ReaderThread::*)(Reader, SyncController&)>, std::shared_ptr<ReaderThread>, Reader, std::reference_wrapper<SyncController> >':
/usr/gcc-4.7.4/lib/gcc/i586-pc-linux-gnu/4.7.4/../../../../include/c++/4.7.4/type_traits:1857:12:   required from 'class std::result_of<std::_Mem_fn<void (ReaderThread::*)(Reader, SyncController&)>(std::shared_ptr<ReaderThread>, Reader, std::reference_wrapper<SyncController>)>'
/usr/gcc-4.7.4/lib/gcc/i586-pc-linux-gnu/4.7.4/../../../../include/c++/4.7.4/functional:1563:61:   required from 'struct std::_Bind_simple<std::_Mem_fn<void (ReaderThread::*)(Reader, SyncController&)>(std::shared_ptr<aeirtuthread::ReaderThread>, Reader, std::reference_wrapper<SyncController>)>'
/usr/gcc-4.7.4/lib/gcc/i586-pc-linux-gnu/4.7.4/../../../../include/c++/4.7.4/thread:133:9:   required from 'std::thread::thread(_Callable&&, _Args&& ...) [with _Callable = void (ReaderThread::*)(Reader, SyncController&); _Args = {std::shared_ptr<ReaderThread>&, Reader&, std::reference_wrapper<SyncController>}]'
./aeirtu/aeirtu/main.cpp:155:96:   required from here
/usr/gcc-4.7.4/lib/gcc/i586-pc-linux-gnu/4.7.4/../../../../include/c++/4.7.4/type_traits:1834:9: error: no match for call to '(std::_Mem_fn<void (ReaderThread::*)(Reader, SyncController&)>) (std::shared_ptr<ReaderThread>, Reader, std::reference_wrapper<SyncController>)'

在/usr/gcc-4.7.4/lib/gcc/i586 pc-linux-gnu/4.7.4/../../../../../../include/c++/4.7.4/bits/move.h:57:0中包含的文件中，
从/usr/gcc-4.7.4/lib/gcc/i586 pc linux gnu/4.7.4/../../../../../../../include/c++/4.7.4/bits/stl_pair.h:61，
从/usr/gcc-4.7.4/lib/gcc/i586 pc-linux-gnu/4.7.4/../../../../../../../include/c++/4.7.4/bits/stl_-algobase.h:65，
从/usr/gcc-4.7.4/lib/gcc/i586 pc-linux-gnu/4.7.4/../../../../../../include/c++/4.7.4/bits/char\u traits.h:41，
从/usr/gcc-4.7.4/lib/gcc/i586 pc-linux-gnu/4.7.4/../../../../../../../include/c++/4.7.4/ios:41，
从/usr/gcc-4.7.4/lib/gcc/i586 pc-linux-gnu/4.7.4/../../../../../../include/c++/4.7.4/ostream:40，
从/usr/gcc-4.7.4/lib/gcc/i586 pc-linux-gnu/4.7.4/../../../../../../include/c++/4.7.4/iostream:40，
from./main.cpp:11:
/usr/gcc-4.7.4/lib/gcc/i586 pc linux gnu/4.7.4/../../../../../../../include/c++/4.7.4/type_traits:在“struct std:：_Result_of_impl”的实例化中：
/usr/gcc-4.7.4/lib/gcc/i586 pc linux gnu/4.7.4/../../../../../../../../include/c++/4.7.4/type_traits:1857:12:从'class std:：result_of'中需要
/usr/gcc-4.7.4/lib/gcc/i586 pc linux gnu/4.7.4/../../../../../../../../../include/c++/4.7.4/functional:1563:61:必须来自“struct std:_Bind\u simple”
/usr/gcc-4.7.4/lib/gcc/i586 pc linux gnu/4.7.4/../../../../../../../../include/c++/4.7.4/thread:133:9:std:：thread:：thread（_Callable&&，_Args&&…[with_Callable=void（readerthreader:：*）（Reader，SyncController&）；_Args={std:：shared(std:：shared(ptr&，)，Reader&，)std:：reference)wrapper
/aeirtu/aeirtu/main.cpp:155:96:此处需要
/usr/gcc-4.7.4/lib/gcc/i586 pc linux gnu/4.7.4/../../../../../../../include/c++/4.7.4/type_traits:1834:9:错误：调用（std:_Mem_fn）（std:：共享_ptr，Reader，std:：reference_wrapper）不匹配

我无法确定此错误是由在旧编译器上使用

std:：ref

引起的，还是由其他原因引起的

---

帮助您找到4.7.4支持的修复程序并编译我的代码。

gcc 4.7似乎无法处理作为对象提供的共享\u ptr（或唯一\u ptr）。不过，它可以很好地使用自然指针，所以一个可能的解决方案是用以下内容替换线程创建（当然，如果合适的话）：

现在，如果这是不可行的，并且需要真正的分配指针，那么以下是您想法的替代方案：

  std::thread th(
                 [ptr, &syncController, myReader] () {
                      ptr->start(myReader, syncController);
                 }
                );

}

---

在本例中，SyncController是通过引用传递的，其他所有内容都是通过值传递的，与您的文章中的方式相同。

虽然GCC4.8.x几乎完全支持c++11，但GCC4.7.x缺少一些功能。检查这里：确实如此，但我需要修复编译代码。。。感谢帮助…使用指针而不是引用。被自然指针替换，现在它工作正常。。。无论如何，我也会尝试第二个建议。。。谢谢。@Mendez，自然的指针，当然，是最前卫的。这里唯一需要注意的是，如果您需要管理对象的生命周期，自然指针可能不起作用。