In C# (at least using .NET, but I think it's general), you can create events like this: Understanding events and event handlers in C#.
Is there a similar mechanism for C++?
PS: I've never liked signal/slot system, so please don't suggest it, since I'm already using it and would love to switch to something else.
The event mechanism in C# is really just a formal, language implemented version of the Observer Pattern. This pattern can be implemented in any language, including C++. There are many examples of implementations in C++.
The largest and most common implementation is probably Boost.Signals and Boost.Signals2, though you explicitly mentioned not liking the signal/slot style implementations.
Event.h can be downloaded from the link bellow, it provides a .NET like Event implemented in C++: http://www.codeproject.com/Tips/1069718/Sharp-Tools-A-NET-like-Event-in-Cplusplus
An example of its usage:
#include "Event.h" // This lib consists of only one file, just copy it and include it in your code.
// an example of an application-level component which perform part of the business logic
class Cashier
{
public:
Sharp::Event<void> ShiftStarted; // an event that pass no argument when raised
Sharp::Event<int> MoneyPaid; // will be raised whenever the cashier receives money
void Start(); // called on startup, perform business logic and eventually calls ProcessPayment()
private:
// somewhere along the logic of this class
void ProcessPayment(int amount)
{
// after some processing
MoneyPaid(amount); // this how we raise the event
}
};
// Another application-level component
class Accountant
{
public:
void OnMoneyPaid(int& amount);
};
// The main class that decide on the events flow (who handles which events)
// it is also the owner of the application-level components
class Program
{
// the utility level components(if any)
//(commented)DataStore databaseConnection;
// the application-level components
Cashier cashier1;
Accountant accountant1;
//(commented)AttendanceManager attMan(&databaseConnection) // an example of injecting a utility object
public:
Program()
{
// connect the events of the application-level components to their handlers
cashier1.MoneyPaid += Sharp::EventHandler::Bind( &Accountant::OnMoneyPaid, &accountant1);
}
~Program()
{
// it is recommended to always connect the event handlers in the constructor
// and disconnect in the destructor
cashier1.MoneyPaid -= Sharp::EventHandler::Bind( &Accountant::OnMoneyPaid, &accountant1);
}
void Start()
{
// start business logic, maybe tell all cashiers to start their shift
cashier1.Start();
}
};
void main()
{
Program theProgram;
theProgram.Start();
// as you can see the Cashier and the Accountant know nothing about each other
// You can even remove the Accountant class without affecting the system
// You can add new components (ex: AttendanceManager) without affecting the system
// all you need to change is the part where you connect/disconnect the events
}
