generic-programming

I need to Understand that whether really Inheritance & virtual functions not necessary in C++ and one can achieve everything using Generic programming . This came from Alexander Stepanov and Lecture I was watching is Alexander Stepanov: STL and Its Design Principles I always like to think of templates and inheritance as two orthogonal concepts, in the very literal sense: To me, inheritance goes "vertically", starting with a base class at the top and going "down" to more and more derived classes. Every (publically) derived class is a base class in terms of its interface: A poodle is a dog is an

I have the following problem. Say you want to write a generic function that can take a lambda expression. I understand that if the parameter is of type std::function, then I could not only use lambdas, but also functions and even pointers to functions. So at a first step, I did the following: void print(std::function<void(int, int)> fn) { fn(1,2); } int main() { print([](int i, int j) { std::cout << j <<','<<i<<'\n'; }); return 0; } Now the problem is that I want to make this function generic, meaning that I don't want the lambda expression to have only two parameters. So I tried changing the

I have a server built with java and spring. What i am trying to do is that my controller with the same endpoint will get two different objects. This is an example for what I mean: I know I can do that: public class Option1{ private String name; ... //getter and setter } public class Option2{ private Long id; ... //getter and setter } @Controller public class Controller{ @RequestMapping(value = "service/getData/option1", method = RequestMethod.POST) @ResponseBody public String searchProv(@ResponseBody Option1 data1){ return "option1" } @RequestMapping(value = "service/getData/option2", method =

Is it possible to have a generic constructor that takes any type of initializer list, even if this has nested lists within? Say you have the following partial template specialization for a class that takes in its constructor nested initializer lists: template class ClassA; template <> class ClassA<4> { typedef std::initializer_list<double> list_type; typedef std::initializer_list<list_type> llist_type; typedef std::initializer_list<llist_type> lllist_type; typedef std::initializer_list<lllist_type> initializer_type; size_t n_[4] = {0}; double* data_; public: ClassA(initializer_type l) { assert

When you want to pull an element out of a data structure, you have to give its index. But the meaning of index depends on the data structure itself. class Indexed f where type Ix f (!) :: f a -> Ix f -> Maybe a -- indices can be out of bounds For example... Elements in a list have numeric positions. data Nat = Z | S Nat instance Indexed [] where type Ix [] = Nat [] ! _ = Nothing (x:_) ! Z = Just x (_:xs) ! (S n) = xs ! n Elements in a binary tree are identified by a sequence of directions. data Tree a = Leaf | Node (Tree a) a (Tree a) data TreeIx = Stop | GoL TreeIx | GoR TreeIx --

(As an excuse: the title mimics the title of Why do we need monads? ) There are containers (and indexed ones) (and hasochistic ones) and descriptions . But containers are problematic and to my very small experience it's harder to think in terms of containers than in terms of descriptions. The type of non-indexed containers is isomorphic to Σ — that's quite too unspecific. The shapes-and-positions description helps, but in ⟦_⟧ᶜ : ∀ {α β γ} -> Container α β -> Set γ -> Set (α ⊔ β ⊔ γ) ⟦ Sh ◃ Pos ⟧ᶜ A = ∃ λ sh -> Pos sh -> A Kᶜ : ∀ {α β} -> Set α -> Container α β Kᶜ A = A ◃ const (Lift ⊥) we are