Hi!
jason.cipriani@gmail.com schrieb:
// 'A' is just a run-of-the-mill template class.
template <class T> class A {
public:
void doit () {
std::printf("A<%s>::doit()\n", typeid(T).name());
}
};
and
void B::call_doit () {
if (t_ == tInt)
call_doit_helper<int>();
else if (t_ == tFloat)
call_doit_helper<float>();
else
assert(0);
}
This looks like a manual virtual function dispatch. I suggest you create a
base class for all A<T> which has a virtual destructor and an abstract
doit() function.
1. There's nothing weird going on here with that cast, right?
Everything should work out OK?
Yes, all is ok.
2. In B's destructor, will that destroy the A<T> appropriately?
Yes, correct dtor.
3. Is static_cast<> what I want to be using here (as opposed to
reinterpret_cast, I guess)?
Yes, use static_cast.
Again maybe this is a silly question but I've been confusing the heck
out of myself staring at this code all day.
How about:
struct BaseDoIt
{
virtual ~BaseDoIt() {}
virtual void doit() =0;
};
//copied from your code, but BaseDoIt added:
template <class T> class A : BaseDoIt {
public:
void doit () {
std::printf("A<%s>::doit()\n", typeid(T).name());
}
};
// non template class
struct B
{
// but template ctor:
template<typename T>
B();
void call_doit();
private:
const std::auto_ptr<BaseDoIt> helper;
};
template<typename T>
B::B()
: helper(new A<T>())
{
}
void B::call_doit()
{
helper->doit();
}
This is even safer. And cleaner! And faster!
Frank
Can't call a member function in the constructor initializer list...