c++, stl map of pointers to functions vectors

Question

i seem to have some problem in creating a structure defined as the topic.

My objective is to create a sort of event handler, (it doesn't matter if it's good or bad programming,or if it is not multithread: for the moment is just for practice).

My idea is then to create a vector of pointers to functions, and place this vector in a map,where the key is a string.

i must be doing something conceptually wrong, because i get some strange errors: My code is as following (errors are at the end):

.h file
//ptr to function
typedef int (*pt2Function)(void*);
typedef std::vector<pt2Function> fPtrVector;

class eventDispatcher
{

public:
    //stuff 
    void addListener(std::string,pt2Function);

protected:
    //stuff
     std::map<std::string,fPtrVector> _listeners;
};

and here is the cpp:

.cpp file

void eventDispatcher::addListener(std::string eventName ,pt2Function function)
{
  std::map<std::string,fPtrVector>::iterator it;

  it=this->_listeners.find(eventName);
  if(it != this->_listeners.end())
  {
//do something
  }
  else 
  {
    std::vector<pt2Function> tmp;
    tmp.insert(function);  // here occurs error 1

    this->_listeners.insert(eventName,tmp);  // here occurs error 2
    std::cout<<"cnt: "<< this->_listeners.count(); 
  } 

}

The errors i get are:

1)  no matching function for call to 'std::vector <int (*)(void*), std::allocator<int (*)(void*)> >::insert(int (*&)(void*))'

2)  no matching function for call to 'std::map<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::vector<int (*)(void*), std::allocator<int (*)(void*)> >, std::less<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::vector<int (*)(void*), std::allocator<int (*)(void*)> > > > >::insert(std::string&, std::vector<int (*)(void*), std::allocator<int (*)(void*)> >&)'

Answer 1

No variation of std::vector::insert() takes a single argument: all take an iterator indicating the position to which the new element(s) must be inserted before. Use std::vector::push_back() to add function instead.

std::map::insert() has several variations, but the one you are attempting to use takes the value_type of the map , which is defined as:

value_type  std::pair<const Key, T>

in your case the value_type is a std::pair<std::string, fPtrVector> :

this->_listeners.insert(std::pair(eventName,tmp));

Answer 2

If you check a reference to insert you see that it takes two arguments, an iterator and the value. To just add a value use eg push_back instead.

For the map, you can use _listeners[eventName] = tmp; instead.

Answer 3

1) The insert() method of std::vector works by specifying a position using an iterator. For your case, you can use push_back() .

2) Use insert(std::make_pair(eventName, tmp)) and that will create the required value type by the map.

Answer 4

1. You are looking for std::vector::push_back ( see the documentation for std::vector here ).

2. You are looking for std::map::operator [] ( see the documentation for std::map here ).