Re: [Boost-users] bind/function: composition

From: Johan Torp (johan.torp_at_[hidden])
Date: 2006-10-03 03:21:59

Monday, October 2, 2006, 10:05:23 PM, you wrote:
burlbo> Johan Torp wrote:
>> 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));

burlbo> Why not just use Boost Signals to have a single signal just call your
burlbo> two different slots of foo and bar ? It seems you are unnecessarily
burlbo> trying to re-invent a wheel which has already been re-invented by the
burlbo> signals library.

Good point. Actually I have developed some classes which closely
resemble the signals library which I had already used extensively
when I found signals. Maybe I will switch to boost signals when some
shortcoming of my "library" becomes appearent, but for now it works
nicely and I prefer to not mix APIs.

In this particular case, boost::lambda solved the problem. I have a strong
functional programming background so doing things like this (higher
order programming) is much more natural to me than having to think about
concepts such as signals and slots.

-- 
Best regards,
 Johan Torp                         mailto:johan.torp_at_[hidden]