I am creating an input manager, that stored events, and associated methods (std::function<void()>) to call when an event occurs. However, there may be multiple events to call when an event was fired. The obvious way of storing the event - function paring would be a linked list, but as there may be multiple functions this won't work. I'm thinking of just having a linked list which stores arrays of std::function<void()> as the elements. Is this an appropriate method to use, and if not what is the safest approach?
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roalz
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w4etwetewtwet
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1If it stores events and functions, why not a map? For multiple functions, a multimap. – chris Jul 24 '13 at 08:47
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@chris Thanks, sounds like what I want. I don't have much knowledge of what data structures are prebuilt into c++, so this is a great help! – w4etwetewtwet Jul 24 '13 at 08:51
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@handuel, http://stackoverflow.com/a/471461/962089 – chris Jul 24 '13 at 08:52
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@chris thanks once again. Bookmarked. – w4etwetewtwet Jul 24 '13 at 08:53
1 Answers
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Store your mapping of Event->Function in a multimap, which can store key/value combinations with duplicate keys.
std::multimap<Event, std::function<void()>> events_;
When an event is fired, you can find a list of all event handlers using equal_range which returns a std::pair of iterators of all the event handling functions. Call each of these to handle the event, e.g. (untested code)
void on_event(Event const &e) {
for (auto r = events_.equal_range(e); r.first != r.second; ++r.first)
r.first->second();
}
equal_range returns a pair of iterators, so loop between the two. On each iteration of the loop the iterator (r.first) points to a key/value pair. r.first->first will be e and r.first->second will be the function handler.
cdmh
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Thank you, fully answers the question, and thanks for showing me how to get all the event handlers. – w4etwetewtwet Jul 24 '13 at 09:21