Re: [Boost-users] What's wrong with my code?

On Sun, May 4, 2014 at 5:08 AM, Bill David wrote:

Hi all,

I meet a problem with some code with boost and want to ask for some help here.

To the following code:

#include <list>

using namespace std;

#include "boost/function.hpp"

#include "boost/foreach.hpp"

#include "boost/bind.hpp"

using namespace boost;

void InsertItemHelper(list<int>& inContainer, list<int>::iterator& ioPosition, const list<int>::value_type& inItem)

{

ioPosition = inContainer.insert(ioPosition, inItem);

}

void WorkerFunction(const list<int>& inContainer, boost::function const& inAddItemCallback)

{

BOOST_FOREACH(auto item, inContainer)

{

inAddItemCallback(item);

}

}

void Print(const list<int>& inContainer)

{

BOOST_FOREACH(auto item, inContainer)

{

std::cout << item << endl;

}

}

int main()

{

list<int> sourceContainer;

sourceContainer.push_back(1);

sourceContainer.push_back(2);

sourceContainer.push_back(3);

list<int> targetContainer;

list<int>::iterator pos = targetContainer.end();

boost::function addItemCallbackFxn(boost::bind(& InsertItemHelper, targetContainer, pos, _1));

WorkerFunction(sourceContainer, addItemCallbackFxn);

return 0;

}

When I run it on Windows with VS2012, I always get a “list insert iterator outside range” error with:

inContainer.insert(ioPosition, inItem);

It seems targetContainer I passed to boost::bind is copied so that the following debug error of STL is hit:

#if _HAS_ITERATOR_DEBUGGING if (_Where._Mycont != this) _DEBUG_ERROR("list insert iterator outside range"); #endif /* _HAS_ITERATOR_DEBUGGING */

But I am passing targetContainer as a reference and after the error, I can correctly get data in it.

Does anybody know what’s wrong behind?

Thanks,

BD

boost::bind copies the arguments into a functor that it returns. boost::ref (mutable reference) or boost::cref (const reference) can be used to change this behavior. addItemCallbackFxn(boost::bind(InsertItemHelper, boost::ref(targetContainer), boost::ref(pos), _1)); Lee