c++ - QtConcurrent::blockingMapped() 和 std::vector<> 错误

Question

QtConcurrent 似乎与 QT 容器(QList 和 QVector)一起工作良好，但与声称的 in the documentation 相反，它与 STL 容器一起失败。

这是我想在我的容器上使用的虚拟函数:

void addOne(int & i)
{
    ++i;
}

int addOneC(const int & i)
{
    return i+1;
}

有效的例子:

int main( int argc, char** argv )
{
    // Qt containers
    QList<int> l;
    l << 1 << 2 << 4 << 3;
    QList<int> l1 = QtConcurrent::blockingMapped(l, addOneC);
    QtConcurrent::blockingMap(l1, addOne);

    // Standard containers
    vector<int> v;
    v.push_back(1);
    v.push_back(2);
    v.push_back(4);
    v.push_back(3);
    QtConcurrent::blockingMap(v, addOne);
}

什么不起作用:

int main( int argc, char** argv )
{
    // Standard containers
    vector<int> v;
    v.push_back(1);
    v.push_back(2);
    v.push_back(4);
    v.push_back(3);
    vector<int> v1 = QtConcurrent::blockingMapped(v, addOneC);
}

它会导致一个编译错误，其中包含非常长且令人困惑的模板错误。

如果有人知道原因，那真的很有帮助!谢谢!

---

错误日志:

1>C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\include\xutility(442) : error C2825: '_Alloc': must be a class or namespace when followed by '::' 1> .\main.cpp(187) : see reference to class template instantiation 'std::_Container_base_aux_alloc_real<_Alloc>' being compiled 1> with 1> [ 1> _Alloc=int 1> ] 1>C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\include\xutility(442) : error C2903: 'rebind' : symbol is neither a class template nor a function template 1>C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\include\xutility(442) : error C2039: 'rebind' : is not a member of 'global namespace''
1>C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\include\xutility(442) : error C2143: syntax error : missing ';' before '<'
1>C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\include\xutility(442) : error C2039: 'other' : is not a member of 'global namespace'' 1>C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\include\xutility(442) : error C2238: unexpected token(s) preceding ';' 1>.\main.cpp(187) : error C2248: 'std::_Container_base_aux_alloc_real<_Alloc>::~_Container_base_aux_alloc_real' : cannot access protected member declared in class 'std::_Container_base_aux_alloc_real<_Alloc>' 1> with 1> [ 1> _Alloc=int 1> ] 1> C:\Program Files (x86)\Microsoft Visual Studio 9.0\VC\include\xutility(435) : see declaration of 'std::_Container_base_aux_alloc_real<_Alloc>::~_Container_base_aux_alloc_real' 1> with 1> [ 1> _Alloc=int 1> ] 1>.\main.cpp(187) : error C2440: 'initializing' : cannot convert from 'std::_Container_base_aux_alloc_real<_Alloc>' to 'std::vector<_Ty>' 1> with 1> [ 1> _Alloc=int 1> ] 1> and 1> [ 1> _Ty=int 1> ] 1> No constructor could take the source type, or constructor overload resolution was ambiguous

Answer 1

我认为您应该明确地将容器的类型指定给 blockingMapped。

int main( int argc, char** argv )
{
    std::vector<int> v;
    v.push_back(1);
    v.push_back(2);
    v.push_back(4);
    v.push_back(3);

    std::vector<int> v1 = QtConcurrent::blockingMapped<std::vector<int> >(v, addOneC);
}

在你给出的简单例子中编译并给我预期的结果。