Re: [Boost-Users] How to use boost::bind

From: Darren Cook (darren_at_[hidden])
Date: 2003-08-25 21:21:56

>>while(i!=c->points.end()){
>>	Info *ec=cs.get(*i++);
>>	list.add(ec->key);
>>	//Previous two lines could be written:  list.add(cs.get(*i++)->key);
>>	}
> 
> grab_keys2 would look like this:
> 
> void grab_keys2(const AllInfo &cs,const Info *c){
> Points list;
> std::for_each(c->points.begin(),c->points.end(),
> 	boost::bind(&Points::add, 
> 		boost::bind(&Info::key,
> 			boost::bind(&InfoContainer::get, &cs, _1))));    

Thanks for the reply. I can almost match that up to the parts in the while 
loop, except mention of "list" is missing. Should it be:

          boost::bind(&Points::add, &list,
                  boost::bind(&Info::key,
                          boost::bind(&InfoContainer::get, &cs, _1))));

> However, if Points is std::set<int>, then "add" should be "insert" 

Sorry. Points is a class that can be thought of as a wrapper for std::set. I 
thought I could simplify the example by substituting, but of course I hadn't 
thought it through properly had I.

BTW, I was hoping I'd be able to do something like this:
     std::for_each(c->points.begin(),c->points.end(),
         list.add(cs.get( _1 )->key)
          );

But after some experiments with boost::lambda I see why this isn't possible. 
  I think if just one call to bind is possible then it is worth it, but when 
bind is required 2 or more times, falling back to a while loop or a functor 
seems better. Is anyone else using a similar guideline?

Darren