“type-switch” construct in C++11

Question

All the time, I find myself doing something like this:

Animal *animal = ...
if (Cat *cat = dynamic_cast(animal)) {
    ...
}
else if (Dog *dog =         


        

Answer 1

Implementation

template 
void action_if(B* value, std::function action)
{
    auto cast_value = dynamic_cast(value);
    if (cast_value != nullptr)
    {
        action(cast_value);
    }
}

Usage

Animal* animal = ...;
action_if(animal, [](Cat* cat)
{
    ...
});
action_if(animal, [](Dog* dog)
{
    ...
});

I don't have access to a C++11 compiler right this second to try this out, but I hope the idea is useful. Depending on how much type inference the compiler is capable of, you may or may not have to specify the case's type twice - I'm not C++11-pro enough to tell from looking at it.