Graph_lib::Window win(Point(100, 100), 600, 600, "Function graphs"); const int r_min = -10, r_max = 11, n_points = 400; Function one([](double x) { return 1.0; }, r ...

This calls the internal builder.graph() which is const, and makes no modifications to organizer state that I can tell. Looks like it should be marked const.