I have a base class and a few derivative. I have to 'register' some static function from each of them. Here is the example:
class Base
{
// Some interface...
};
class Der1 : Base
{
static void Do();
};
class Der2 : Base
{
static void Do();
};
void processStatic()
{
SomeFunc(Der1::Do);
SomeFunc(Der2::Do);
}
As you see, SomeFunc
receives function pointer. I w开发者_开发知识库ant to do that automatically with each new derivative class, is it possible? Maybe, predefine static function in Base
class and register it there. But I think it's impossible, yes?
Maybe, this will be more easier to understand what do I want:
class Der1 : Base
{
Der1() { SomeFunc(Der1::Do); }
static void Do();
};
class Der2 : Base
{
Der2() { SomeFunc(Der2::Do); }
static void Do();
};
EDIT: Completely replacing previous answer due to clarified requirements.
You could use the CRTP to declare a specialized base class that does nothing more than call your registration function:
#include <iostream>
void SomeFunc(void(*fp)()) {
(*fp)();
};
template <class D>
struct ExtraBass {
ExtraBass() {
static bool once;
if(!once)
SomeFunc(D::Do);
once = true;
}
};
struct Bass {
};
struct Drive : Bass, ExtraBass<Drive> {
static void Do() { std::cout << "Drive::Do\n"; }
};
struct Deride : Bass , ExtraBass<Deride> {
static void Do() { std::cout << "Deride::Do\n"; }
};
int main() {
Drive d1;
Deride d2;
Deride d3;
}
This is not an easy thing to do in C++, but I'm not saying it's impossible. If all you need is a list of subclass names, these answers might help:
Somehow register my classes in a list
c++ List of classes without initializing them for use of static functions
Seems either macro magic or boost mpl is your tool of choice.
I just wondering, if you did something like
void SomeFunc(void (*doFunc)())
{
doFunc();
}
template <class T> int Register()
{
SomeFunc(T::Do);
return 0;
}
template <class T> class Base
{
static int _i;
};
template <class T> int Base<T>::_i = Register<T>();
class Derived : Base<Derived>
{
public:
static void Do() { }
};
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