从列表中删除回调函数？

Question

Okay, I have a list of callbacks, Callback is defined as follows:

typedef std::function<void(Event*)> Callback;

Now If I try to remove an object from that list via

callbackBindings[index].remove(callback);

I get

Error 100 error C2248: 'std::function<_Fty>::operator ==' : cannot access private member declared in class 'std::function<_Fty>' D:\\Programme\\Development\\Visual Studio Ultimate 2012\\VC\\include\\list 1592 1 D-Tris

How can I remove an element from that list ?

PS: CallbackBindings looks like this:

static std::unordered_map<std::type_index, std::list<Callback>> callbackBindings;

Answer 1

You cannot compare std::function objects for equality. You will have to remove them by other means, eg by index or iterator (which you have to store at the time of saving the callback), or by map key in an associative container.

(For example, imagine you inserted to callbacks that you specified locally as [](Event*){} . There is no mechanism or logic for telling whether any two such expressions should be considered "equal".)