[Boost-users] bind/function: composition

From: Johan Torp (johan.torp_at_[hidden])
Date: 2006-10-02 07:30:45

I often tend to have interfaces which take a boost::function<void()> 
that is to be called when an event occurs. Quite often I need make two 
separate function calls as response to one event. In these cases I 
usually solve the problem using the following technique:

void foo();
void bar();

void call_two(const boost::function<void ()>& one,  const 
boost::function<void ()>& two)
{  one();  two(); }

boost::function<void ()> on_event = boost::bind(&call_two, 
boost::bind(&foo), boost::bind(&bar));

Is there any other way to acheive this, beside having to redeclare and 
define a function such as call_two?

It seems quite easy to define something like:

template <typename R1, typename R2>
void nullary_compose boost::function<R1 ()>& one, const 
boost::function<R2 ()>& two);
template <typename R1, typename R2, typename R3>
void nullary_compose boost::function<R1 ()>& one, const 
boost::function<R2 ()>& two, const boost::function<R3 ()>& three);
...

Is anybody else interested in seeing such templates in boost?

Best Regards,
Johan Torp

-- 
System Developer
TouchTable AB
Tel: [phone]
johan.torp_at_[hidden]