From: James Hughes <JHughes@Linx.co.uk> Date: Tue, 11 Apr 2006 10:14:12 +0100

Hello all,

I have a feeling this may be off the topic of Boost, so if anyone can point me in the direction of a better place to ask please do (a templates mailing list?). However, I post it here because I think Boost::Bind does something similar internally to what I want to do, so someone may be able to advise.

I have a couple of templated class which implement a simple observer pattern (yes I know Boost has signals, but it's not thread safe).

It uses a virtual function to make a call in to the observer from the subject. My own observer then derive from this class and implement the notify function. However, I would like to 'template' the name of the function, so that different instances of the template can make calls to different named function.

Now in Boost:bind you specify the name of the function in the class to be called, but I don't know how to implement that in my own template class.

class observer<typename T> { virtual void Notify(T&); // This is the function I want to rename according to the template }

so I might want, in a different instance, the Notify function to be called, Shutdown(). Following code is NOT valid C++, but gives an idea of what I am trying to implement, but don't know enough yet to do so!!

class observer<typename T, typename functionname> { virtual void <functionname>(T&) }

Is there a way I can use templates to do this? Boost:bind can call a particular member function passed in as part of the template defn, how do I that?

I hope that is vaguely clear...

James

Have you checked out Boost.Function? You can use a boost::function<void (T &)> instance in your class to point to the correct member function you want to call. Alternatively, you may try to use member function pointer: template <typename T, void (Observer::*Notify)(T & )> class .... { } Just my 5 cents... Cheers, Freddie