Re: [boost] boost::range needs help

From: Neal Becker (ndbecker2_at_[hidden])
Date: 2007-09-25 10:35:39

Thorsten Ottosen wrote:

> Neal Becker skrev:
>> boost::size of a std::list gives:
>> 
>> /usr/local/src/boost.hg/boost/range/size.hpp:28: error: no match
>> for 'operator-' in 'boost::end [with T = std::list<double,
>> std::allocator<double> >](((const std::list<double,
>> std::allocator<double>
>>> &)((const std::list<double, std::allocator<double> >*)r))) -
>>> boost::begin
>> [with T = std::list<double, std::allocator<double> >](((const
>> std::list<double, std::allocator<double> >&)((const std::list<double,
>> std::allocator<double> >*)r)))'
>> 
>> I would hope that boost::size (type with member .size()) would use the
>> member .size().
> 
> Use boost::distance( my_list );
> 
> size() was changed to reflect O(1) complexity.
> 
> -Thorsten

Sorry, I don't think that was my question.  boost::size(T t) has a default
implementation using t.end()-t.begin() (in boost/range/size.hpp).  I can
supply my own implementation of size(std:list<T>).  I was wishing that
boost::size would implement boost::size using the member .size() if it
exists.

Perhaps this could be done with enable_if?