AMDG On 04/02/2011 04:15 PM, Littlefield, Tyler wrote:

Hello all: I have a quick question. I was trying to learn how to use boost::mem_fn to work as a sort of function object, because I need something like this for my library. So: If I understand this correctly, it creates a function object that has () overloaded, correct? I was curious if someone could then help me figure this out, the documentation is confusing for me. lets say I have this class: class Foo { public: int Add(int a, int b) { return (a+b); } };

and I could do Foo bar; how would I create a mem_fn named f, that would let me call it for add? so: f(3,1). I would have to tie the instance of foo (bar) to this somehow, correct?

Yes. That's what bind does.

Next, I see that mem_fn creates a function object which basically does what I want. What then is the point in boost::bind? It looks to do about the same as mem_fn, just makes my head hurt a little bit more.

mem_fn doesn't do any argument binding. It only adapts a member function to be a regular function object. boost::mem_fn(&Foo::Add) takes 3 arguments.

I am trying to learn boost by finding uses for some of the libraries. Some of them sort of makes sense, but I see that mem_fn are the bases for a lot, so I wanted to learn how to use those. After bind and mem_fn, what other libraries would it be best to learn that is used all over? Last, this is the use I will be putting mem_fn to. If this is incorrect, I still want to learn, but it looked like a great example. I am writing a quick socket class that will have connect, close, and send capabilities. I am hooking this to my game engine, and wanted to use a mem_fn to receive the data. So the server polls all user input, then it will poll the sockets that were added to another list. It will pass off any data read by calling the function object with the data as an argument, as well as the socket.

That sounds rather like what Boost.Asio does.

Sorry for all the questions, and thanks in advance for the help/clarification.

In Christ, Steven Watanabe