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

>> 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(&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:
         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?


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