Re: [Boost-users] logical_and, boost::bind, and boost::function

From: Douglas Gregor (doug.gregor_at_[hidden])
Date: 2005-08-10 12:42:05

On Aug 10, 2005, at 11:44 AM, Simmons, Aaron wrote:
>         function<bool ()> funcFoo  = bind(&test::foo, this);
>         function<bool ()> funcBar  = bind(&test::bar, this);
>         function<bool ()> funcTest1= bind(logical_and<bool>(), 
> funcFoo, funcBar);

Alan's post made me realize what's happening. Indeed, this last bind() 
doesn't know that funcFoo and funcBar are functions that it should 
call. You can tell it to consider them as functions by calling bind() 
on them:

        function<bool ()> funcTest1= bind(logical_and<bool>(), bind(funcFoo), 
bind(funcBar));

Now it should work fine. Whether it's actually clearer or not is for 
you to decide, but here's one warning: each call through a 
boost::function object is like a virtual function call. So by turning 
each call to one boost::function object into a call through 3 
boost::function objects, there will be a performance penalty.

        Doug