Comparing std::tr1::function<> objects

c++ function tr1
AlexG picture AlexG · Sep 18, 2008 · Viewed 7k times · Source

I've been trying to implement a C#-like event system in C++ with the tr1 function templates used to store a function that handles the event.

I created a vector so that multiple listeners can be attached to this event, i.e.:

vector< function<void (int)> >  listenerList;

I'd like to be able to remove a handler from the list to stop a listener receiving events.

So, how can I find the entry in this list that corresponds to a given listener? Can I test if a 'function' object in the list refers to a particular function?

Thanks!

EDIT: Having looked into the boost::signal approach, it seems it's probably implemented using a token system as some of you have suggested. Here's some info on this. An observer retains a "Connection" object when they attach to an event, and this connection object is used to disconnect if needed. So it looks like whether you use Boost or roll your own with tr1, the basic principle's the same. i.e. it will be a bit clumsy :)

Answer

Nick Bastin picture Nick Bastin · Sep 18, 2008

I don't know if you're locked into std C++ and tr1, but if you aren't, it seems like your problem could be completely avoided if you just used something like boost::signal and boost::bind to solve your original problem - creating an event system - instead of trying to roll your own.

Related questions

Using generic std::function objects with member functions in one class

For one class I want to store some function pointers to member functions of the same class in one map storing std::function objects. But I fail right at the beginning with this code: #include <functional> class Foo { …

Read More
C++: Function wrapper that behaves just like the function itself

How can I write a wrapper that can wrap any function and can be called just like the function itself? The reason I need this: I want a Timer object that can wrap a function and behave just like the …

Read More
Why is std::function not equality comparable?

This question also applies to boost::function and std::tr1::function. std::function is not equality comparable: #include <functional> void foo() { } int main() { std::function<void()> f(foo), g(foo); bool are_equal(f == g); // Error: …

Read More