boost::bind, boost::shared_ptr and inheritance - c++

Question

I'm new with the Boost library, and I got a problam a bit complex for me.
I tried to reformulate it with an example found in previous question that might fit well my problem.
(The previous question is here)
#include <boost/bind.hpp>
#include <iostream>
#include <map>
#include <set>
#include <algorithm>
#include <boost/noncopyable.hpp>
#include <boost/shared_ptr.hpp>
#include <boost/enable_shared_from_this.hpp>
class Base
: public boost::enable_shared_from_this<Base>,
private boost::noncopyable
{
public:
virtual void test() = 0;
protected:
virtual void foo(int i) = 0;
};
class Derived
: public Base
{
protected:
void foo(int i)
{ std::cout << "Base: " << i << std::endl; }
std::map<int, int> data;
public:
Derived()
{
data[0] = 5;
data[1] = 6;
data[2] = 7;
}
void test()
{
std::for_each(data.begin(), data.end(),
boost::bind(&Derived::foo, shared_from_this(),
boost::bind(&std::map<int, int>::value_type::second, _1)));
}
};
typedef boost::shared_ptr<Base> Base_ptr;
int main(int, const char**)
{
std::set<Base_ptr> Bases_;
Base_ptr derived(new Derived());
Bases_.insert(derived);
derived->test();
return 0;
}
I have a base object which is contained in a set, and different derived objects (in this example, only one).
The derived object should call his own protected method with a boost::bind.
In the real problem, the boost::bind generate a callback method for an asynchronous operation, it's why (I think) I need a shared_ptr.
Otherwise, using the pointer this instead of shared_from_this() resolve the problem.
When I compile this code, I got a long error message ended with (which I think is the most significant part):
bind_test.cpp:43:78: instantiated from here
/usr/include/boost/bind/mem_fn_template.hpp:156:53: error: pointer to member type ‘void (Derived::)(int)’ incompatible with object type ‘Base’
/usr/include/boost/bind/mem_fn_template.hpp:156:53: error: return-statement with a value, in function returning 'void'
I tried to manage with more inheritance from enable_shared_from_this, and some static cast :
#include <boost/bind.hpp>
#include <iostream>
#include <map>
#include <set>
#include <algorithm>
#include <boost/noncopyable.hpp>
#include <boost/shared_ptr.hpp>
#include <boost/enable_shared_from_this.hpp>
class Base
: public boost::enable_shared_from_this<Base>,
private boost::noncopyable
{
public:
virtual void test() = 0;
protected:
virtual void foo(int i) = 0;
};
class Derived
: public boost::enable_shared_from_this<Derived>,
public Base
{
protected:
void foo(int i)
{ std::cout << "Base: " << i << std::endl; }
std::map<int, int> data;
public:
Derived()
{
data[0] = 5;
data[1] = 6;
data[2] = 7;
}
void test()
{
std::for_each(data.begin(), data.end(),
boost::bind(&Derived::foo, boost::enable_shared_from_this<Derived>::shared_from_this(),
boost::bind(&std::map<int, int>::value_type::second, _1)));
}
};
typedef boost::shared_ptr<Base> Base_ptr;
int main(int, const char**)
{
std::set<Base_ptr> Bases_;
Base_ptr derived(new Derived());
Bases_.insert(derived);
derived->test();
return 0;
}
But I got an error at run-time :
terminate called after throwing an instance of 'boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::bad_weak_ptr> >'
what(): tr1::bad_weak_ptr
Might someone have a clue about how to manage that ?
Thanks.
Etienne.

Answer 1

It works with this workaround, but I'm not satisfied with it, so if someone find a better solution, go ahead.
#include <boost/bind.hpp>
#include <iostream>
#include <map>
#include <set>
#include <algorithm>
#include <boost/noncopyable.hpp>
#include <boost/shared_ptr.hpp>
#include <boost/enable_shared_from_this.hpp>
class Base
: public boost::enable_shared_from_this<Base>,
private boost::noncopyable
{
public:
virtual void test() = 0;
//protected:
virtual void foo(int i) = 0;
};
class Derived
: public Base
{
protected:
void foo(int i)
{ std::cout << "Base: " << i << std::endl; }
std::map<int, int> data;
public:
Derived()
{
data[0] = 5;
data[1] = 6;
data[2] = 7;
}
void test()
{
std::for_each(data.begin(), data.end(),
boost::bind(&Base::foo, shared_from_this(),
boost::bind(&std::map<int, int>::value_type::second, _1)));
}
};
typedef boost::shared_ptr<Base> Base_ptr;
int main(int, const char**)
{
std::set<Base_ptr> Bases_;
Base_ptr derived(new Derived());
Bases_.insert(derived);
derived->test();
return 0;
}