[Boost-users] Re: filter_iterator question

From: David Abrahams (dave_at_[hidden])
Date: 2005-03-22 17:44:56

steve ahlgren <steveahlgren_at_[hidden]> writes:

> Hello all :
>
> I have a filter_iterator question.
>
> I'm wondering if, conceptualy, I can construct an FI doing something
> like the following :
>
> typedef boost::filter_iterator< boost::bind( boost::mem_fn(
> &MyObject::HasQuality ), boost::ref( quality ) ),  MyIterator >
> FilteredIterator;

You don't need mem_fn; bind will handle that implicitly.  

But sure, that'll work in principle.  Just not in practice ;-).  The
problem is that you're putting a runtime expression in the template
where a type is supposed to be.  On the other hand, you could use
make_filter_iterator to generate an appropriate iterator object.

http://www.boost.org/libs/iterator/doc/filter_iterator.html#filter-iterator-operations

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com