Requiring Method Signature

Yes, you can use a functional-style requires expression within your concept to specify that a class has a method with a certain signature. Here's an example:

1#include <concepts>
2
3template <typename T>
4concept Renderable =
5  requires(T obj, int x, int y) {
6    { obj.Render(x, y) } -> std::same_as<void>;
7};
8
9struct Sprite {
10  void Render(int x, int y);
11};
12
13static_assert(Renderable<Sprite>);  // Passes

The Renderable concept requires that for a type T, it must have a member function Render that is callable with two int arguments x and y, and returns void.

The requires expression provides a way to describe the expected function signature. The obj parameter represents an instance of type T, and x and y serve as the arguments to the Render function.

The return type requirement { obj.Render(x, y) } -> std::same_as<void> specifies that invoking Render with x and y should return something of type void.

If the Sprite class meets these requirements (which it does in this case), the static_assert will pass. If Sprite::Render had a different signature, a compile error would occur.