使用find_if和boost :: bind与一组shared_pointers

Question

I have a vector of shared_ptr, I want to combine boost shared_ptr and bind together.

My question is very similar to this , except that instead of "&MyClass::ReferenceFn" I would like to call "&Element::Fn".

Here is a similar piece of code:

typedef boost::shared_ptr< Vertex > vertex_ptr; 
std::set<vertex_ptr> vertices;

void B::convert()
{
...
if( std::find_if(boost::make_indirect_iterator(vertices.begin()), 
                 boost::make_indirect_iterator(vertices.end() ),  boost::bind( &Vertex::id, boost::ref(*this), _1 ) == (*it)->id() ) == vertices.end() )
}

here is the error:

no matching function for call to ‘bind(<unresolved overloaded function type>, const boost::reference_wrapper<B>, boost::arg<1>&)’

NOTE : I am limited to use the C++03.

Answer 1

To call a member function for each object stored in a collection, you need to use a placeholder as the first bound argument of the boost::bind :

boost::bind(&Vertex::id, _1) == (*it)->id())
//                       ~^~

This way, each argument a , will be bound to a member function pointer, and called as (a.*&Vertex::id)() .

However, seeing that the error message says unresolved overloaded function type , it draws a conclusion that your class Vertex can have multiple overloads of member function id . As such, the compiler is unable to tell which one it should pass as the argument of boost::bind . To solve this, use an explicit cast to a member function pointer (the asterisk after colon indicates it's a pointer to a member):

boost::bind(static_cast<int(Vertex::*)()const>(&Vertex::id), _1) == (*it)->id())
//                      ~~~~~~~~~~~~~~~~~~~~^

In the case class Vertex has multiple overloads, say:

int id() const { return 0; }
void id(int i) { }

you will use the first one for binding.