Using Type Traits in Requires Clauses

Yes, you can use type traits in a requires clause to constrain template parameters based on specific properties or relationships between types. This allows you to leverage the existing type traits library in combination with concepts. Here's an example:

1#include <type_traits>
2
3class Player {};
4class Goblin {};
5
6template <typename T>
7  requires std::is_base_of_v<Player, T>
8void attack(T& attacker, Goblin& target) {
9  // Attack implementation
10}
11
12int main() {
13  Player player;
14  Goblin goblin;
15
16  // Valid, Player is a base of Player
17  attack(player, goblin);
18  
19   // Invalid, Goblin is not a base of Player
20  attack(goblin, goblin);
21}

1error: 'attack': no matching overloaded function found
2could be 'void attack(T &,Goblin &)'
3the associated constraints are not satisfied
4the constraint was not satisfied

In this example, the attack function template is constrained using the std::is_base_of_v type trait in the requires clause. This ensures that the attacker parameter is of a type that derives from the Player class.

Attempting to call the function with a Goblin as the attacker will result in a compilation error.