I'm trying to implement a communication system inside of a GUI. I would like to avoid the visitor pattern for maintainability reasons. Likewise making a dynamic_cast if else statement is not maintainable. The closest I've come is implementing multiple dispatch with tables from Scott Meyers' More Effective C++.
So far I have:
SubmitCommand(BaseCommand* pCommand)
{
m_Distpatcher->Dispatch<DerivedCommand1>(pCommand);
m_Distpatcher->Dispatch<DerivedCommand2>(pCommand);
m_Distpatcher->Dispatch<DerivedCommand3>(pCommand);
}
Where I would like to be is:
SubmitCommand(BaseCommand* pCommand)
{
m_Distpatcher->Dispatch<DerivedCommand1,
DerivedCommand2,
DerivedCommand3>(pCommand);
}
Where dispatch is a automated way of checking dynamic_cast results for incoming commands.
template<typename K>
void Dispatch(ICommand* pCommand)
{
auto pConcreteCommand = dynamic_cast<K*>(pCommand);
if (pConcreteCommand)
{
//call Recieve on the interface of the owner class
m_pInstance->Recieve(pConcreteCommand);
}
}
In this case the specific module would be checked at compile time to make sure it has a function for each argument in the template. Is code block 2 possible?
You might do something like:
template <typename ... Ts>
void Distpatcher::Dispatch(BaseCommand* pCommand)
{
(DispatchUnique<Ts>(pCommand), ...); // C++17
}
so
m_Distpatcher->Dispatch<DerivedCommand1,
DerivedCommand2,
DerivedCommand3>(pCommand);
would be equivalent to
m_Distpatcher->DispatchUnique<DerivedCommand1>(pCommand);
m_Distpatcher->DispatchUnique<DerivedCommand2>(pCommand);
m_Distpatcher->DispatchUnique<DerivedCommand3>(pCommand);