C++ Event Handling - issue with const - c++

Question

I already asked about my Problem, now I'm on the next Step. In the code below I have the Problem, that I always have to make the EventHandler (Server::HandleMessage) static. But I need to have it non static to access other Variables in the Server class from within the Handler.
How can I achieve this?
Here my Code:
#include <iostream>
#include <functional>
using namespace std;
class Client{
public:
struct MessageReceiveArgs {
MessageReceiveArgs(int ID, const std::string& Text) : ID(ID), Text(Text) {}
int ID;
std::string Text;
};
std::function<void(MessageReceiveArgs)> onMessageReceive;
Client(){}
void FireEvent(){
this->onMessageReceive(MessageReceiveArgs(16, "SomeText"));
}
};
class Server{
public:
int i;
Server(){
this->client.onMessageReceive = &Server::HandleMessage;
this->i = 5;
}
void FireEvent(){
this->client.FireEvent();
}
Client client;
static void HandleMessage(Client::MessageReceiveArgs args) {
std::cout<<"ID "<<args.ID<<": "<<" "<<args.Text<<std::endl;
//need it non static
//std::cout<<"I: "<<this->i<<std::endl;
}
};
int main() {
Server sv = Server();
sv.FireEvent();
}
As mentioned in my earlier Post, i'm new to Standard C++ (Unix).

Answer 1

I'm fairly sure this is what you're after. You need to bind the implicit this explicitly when invoking a pointer-to-member through std::function in the fashion you seem to desire.
#include <iostream>
#include <functional>
using namespace std;
class Client{
public:
struct MessageReceiveArgs
{
MessageReceiveArgs(int ID, const std::string& Text)
: ID(ID), Text(Text) {}
int ID;
std::string Text;
};
Client(){}
void FireEvent()
{
this->onMessageReceive(MessageReceiveArgs(16, "SomeText"));
}
std::function<void(MessageReceiveArgs)> onMessageReceive;
};
class Server
{
public:
int i;
Server()
{
this->client.onMessageReceive
= std::bind(&Server::HandleMessage, this, std::placeholders::_1);
this->i = 5;
}
void FireEvent()
{
this->client.FireEvent();
}
Client client;
void HandleMessage(Client::MessageReceiveArgs args)
{
std::cout<<"ID "<<args.ID<<": "<<" "<<args.Text<<std::endl;
}
};
int main()
{
Server sv = Server();
sv.FireEvent();
}
Output
ID 16: SomeText