[Boost-users] functor for boost::thread_group threads: which one is correct?

Subject: [Boost-users] functor for boost::thread_group threads: which one is correct?
From: Boost lzw (boostlzw_at_[hidden])
Date: 2009-08-23 14:56:17

Hi there,

I have two versions (VERSION1 and VERSION2) of a group_helper functor to be
called from boost::thread_group, which one of them is correct?

class FileThread
{
public:
void print() {...}
void find() {...}
};

class group_helper
{
private:
    boost::shared_ptr<FileThread> m_object;
public:
   //VISION1
    group_helper(boost::shared_ptr<FileThread>& object) : m_object(object) {
}

   //VISION2
    group_helper() : m_object(boost::shared_ptr<FileThread>(new FileThread))
{ }

    void operator()() { m_object->find(); m_object->print(); }
};

On another matter, why the following code results in a runtime exception
from the group_helper's dtor?

#include <iostream>
#include "boost/thread/thread.hpp"

class FileThread
{
public:
        void find() { }
        void print() { }
};

class group_helper			
{							
private:
        FileThread* m_object;	
public:			
        group_helper() : m_object(new FileThread) {}
        void operator()() { m_object->find(); m_object->print(); }
        ~group_helper() { if (m_object) delete m_object; }// EXCEPTION from dtor
};

int main()
{
        group_helper gh;
        boost::thread thrd(gh);						
        thrd.join();
}