c++ iterating over member functions - c++

Question

I have a bit of a design problem:
I have a class describing a Robot; It can move to different directions, move a camera to different views etc. It looks something like this:
class Robot {
private:
...
public:
void move_right();
void move_left();
void switch_camera()
void raise_camera()
}
I want to add another method which performs a series of events. Thing is, I need able to abort the events midway.
I do want to clarify that the robot is running on a micro controller and not on a standard OS - so I can't really send a signal to the process or anything.
My first idea was to store the event functions in an array and iterate over it:
#typedef void(robo_event *)(void)
robo_event next_event;
robo_event *event_sequence;
Robot() {
this->next_event = nullptr;
}
void perform_event_series() {
for(this->next_event = *event_sequence; this->next_event != nullptr; this->next_event+=sizeof(robo_event)) {
this->next_event();
}
}
void abort_event_series() {
this->next_event = nullptr;
}
Thing is, the c++ standard forbids storing addresses of member functions, so this is starting to get awkward. I can make the functions static, but I do need to use them quite frequently and that would still be awkward. I want to be able to change to event sequence without too much work if changes are yet to come, so I thought that saving those on some sort of array / vector would be the best.
Any help with c++ member function syntax / better ideas on how to approach this problem would be much appreciated.

Answer 1

Thing is, the c++ standard forbids storing addresses of member functions
C++ most certainly allows you to store pointers to member functions (and variables), but the syntax is a bit different to accommodate the this pointer type, virtual functions, inheritance, etc.
class Example
{
public:
double foo(int x) { return x * 1.5; }
};
int main() {
double (Example::* member_function_ptr)(int);
member_function_ptr = &Example::foo;
Example example;
std::cout << (example.*member_function_ptr)(2) << std::endl;
}
If all your functions are for the same class, same return type, same arguments, etc. then you can make a table of them easy enough.

Answer 2

Storing pointers to member functions is perfectly allowable in c++:
#include <vector>
class Robot {
private:
public:
void move_right();
void move_left();
void switch_camera();
void raise_camera();
};
struct Action
{
Action(void (Robot::*what)(void))
: what(what)
{}
void perform(Robot& who) const
{
(who.*what)();
}
void (Robot::*what)(void);
};
bool should_abort();
void perform_actions(Robot& who, std::vector<Action> const& actions)
{
for (auto&& action : actions)
{
if (should_abort()) break;
action.perform(who);
}
}
int main()
{
std::vector<Action> actions {
&Robot::move_right,
&Robot::raise_camera,
&Robot::switch_camera,
&Robot::move_left
};
Robot r;
perform_actions(r, actions);
}

Answer 3

Pointers to functions are of different types to pointers to members.
You need void(Robot::*)(void) not void(*)(void).
class Robot {
private:
typedef void(Robot::*robot_event)(void)
robo_event next_event;
robo_event *event_sequence;
Robot() {
next_event = nullptr;
}
void perform_event_series() {
for(next_event = *event_sequence; next_event != nullptr; ++next_event) {
(this->*next_event)();
}
}
void abort_event_series() {
next_event = nullptr;
}
public:
void move_right();
void move_left();
void switch_camera()
void raise_camera()
}