Encapsulate thread function with boost bind - c++

Question

I am currently creating boost::threads like this:
boost::thread m_myThread; //member variable
//...
m_myThread = boost::thread(boost::bind(&MyClass::myThreadFunction, this));
This will start a thread which executes a member function "myThreadFunction".
I would like to encapsulate the starting of a new thread and use something like
boost::thread m_myThread; //member variable
//...
startAThread(&m_myThread, boost::bind(&MyClass::myThreadFunction, this), 123 /*some int argument*/);
I thought I could implement "startAThread" like this:
namespace internal
{
template <typename Callable>
void threadhelper(Callable func, int x)
{
doSomething(x);
func();
}
}
template <typename Callable>
void startAThread(boost::thread* threadToCreate, Callable func, int x)
{
*threadToCreate = boost::thread(boost::bind(internal::threadhelper<Callable>, func, x));
}
However, this fails to compile with
usr/include/boost/bind/bind.hpp: In member function 'void boost::_bi::list2<A1, A2>::operator()(boost::_bi::type<void>, F&, A&, int) [with F = void (*)(boost::_bi::bind_t<void, boost::_mfi::mf0<void, MyClass>, boost::_bi::list1<boost::_bi::value<MyClass*> > >, int), A = boost::_bi::list0, A1 = boost::_bi::bind_t<void, boost::_mfi::mf0<void, MyClass>, boost::_bi::list1<boost::_bi::value<MyClass*> > >, A2 = boost::_bi::value<int>]':
usr/include/boost/bind/bind_template.hpp:20: instantiated from 'typename boost::_bi::result_traits<R, F>::type boost::_bi::bind_t<R, F, L>::operator()() [with R = void, F = void (*)(boost::_bi::bind_t<void, boost::_mfi::mf0<void, MyClass>, boost::_bi::list1<boost::_bi::value<MyClass*> > >, int), L = boost::_bi::list2<boost::_bi::bind_t<void, boost::_mfi::mf0<void, MyClass>, boost::_bi::list1<boost::_bi::value<MyClass*> > >, boost::_bi::value<int> >]'
usr/include/boost/thread/detail/thread.hpp:61: instantiated from 'void boost::detail::thread_data<F>::run() [with F = boost::_bi::bind_t<void, void (*)(boost::_bi::bind_t<void, boost::_mfi::mf0<void, MyClass>, boost::_bi::list1<boost::_bi::value<MyClass*> > >, int), boost::_bi::list2<boost::_bi::bind_t<void, boost::_mfi::mf0<void, MyClass>, boost::_bi::list1<boost::_bi::value<MyClass*> > >, boost::_bi::value<int> > >]'
MyClass.cpp:160: instantiated from here
usr/include/boost/bind/bind.hpp:313: error: conversion from 'void' to non-scalar type 'boost::_bi::bind_t<void, boost::_mfi::mf0<void, MyClass>, boost::_bi::list1<boost::_bi::value<MyClass*> > >' requested
What does this error mean? What's wrong with the code?
Thanks a lot!

Answer 1

Try
namespace internal
{
template <typename Callable>
void threadhelper(Callable func, int x)
{
doSomething(x);
func();
}
}
template <typename Callable>
void startAThread(boost::thread& threadToCreate, Callable func, int x) {
threadToCreate = boost::thread(boost::bind(&internal::threadhelper<Callable>, func, x));
}
I also used reference instead of pointer.