Is it possible to define an std::thread and initialize it later?

Question

My aim is to keep an std::thread object as data member, and initialize it when needed.
I'm not able to do this (as in my code below) because the copy constructor of the std::thread class is deleted. Is there any other way to do it?

class MyClass {     public:         MyClass():DiskJobThread(){};         ~MyClass();          void DoDiskJobThread();      private:         int CopyThread(const std::wstring & Source, const std::wstring & Target);         int MoveThread(const std::wstring & Source, const std::wstring & Target);         std::thread DiskJobThread; };  MyClass::~MyClass() {     DiskJobThread.join(); }  void MyClass::DoDiskJobThread() {     std::wstring Source = GetSource();     std::wstring Target = GetTarget();     int m_OperationType = GetOperationType();     if      (m_OperationType == OPERATION_COPY)     {         DiskJobThread = std::thread(&MyClass::CopyThread, *this, Source, Target);     }     else if (m_OperationType == OPERATION_MOVE)     {         DiskJobThread = std::thread(&MyClass::MoveThread, *this, Source, Target);     } } 

Answer 1

How about wrapping it in a pointer?

std::unique_ptr<std::thread> thread_ptr;  // Look into std::make_unique if possible thread_ptr = std::unique_ptr<std::thread>(new std::thread(...)); 

Edit: And yes, the others have mentioned it and I didn't feel the need to add it here, but in order to avoid more downvote piling, I'll say it: You are passing *this and not this thereby copying an instance of your class. (Problems arise because it's non-copyable. Pass this and you should be good to go.)

Answer 2

Your problem is something else - you're passing an instance of MyClass into the thread instead of the pointer to MyClass which the member functions expect. Simply change DoDiskJobThread() like this (do not dereference this):

void MyClass::DoDiskJobThread() {     std::wstring Source = GetSource();     std::wstring Target = GetTarget();     int m_OperationType = GetOperationType();     if      (m_OperationType == OPERATION_COPY)     {         DiskJobThread = std::thread(&MyClass::CopyThread, this, Source, Target);     }     else if (m_OperationType == OPERATION_MOVE)     {         DiskJobThread = std::thread(&MyClass::MoveThread, this, Source, Target);     } } 

You were getting the error because *this resulted in trying to copy MyClass into the thread function, and the copy ctor of your class is deleted (because that of std::thread is deleted). However, the member functions CopyThread and MoveThread require a pointer as the first (hidden) argument anyway.

Live demonstration