Re: [boost] [range] adaptors vs. rvalue to lvalue& binding

Subject: Re: [boost] [range] adaptors vs. rvalue to lvalue& binding
From: Dave Abrahams (dave_at_[hidden])
Date: 2012-03-22 13:27:08

on Thu Mar 22 2012, Arno Schödl <aschoedl-AT-think-cell.com> wrote:

> Hello,
>
> ideally I would like to use range-adapted lvalue ranges like any other lvalue ranges. Writing it down naively, as below, does not compile because LoadRefRange takes (and should take?) the range it modifies by lvalue&, while adaptor expressions are rvalues.

One possibility: 

 - make adaptor expressions return const rvalues. The const rvalues will
   bind to T& arguments (where T is a template parameter) by deducing T
   to be const.

 - make even the const_iterators for such adaptors mutable (writable) iterators

This accurately reflects the fact that such adaptors don't own their values.

-- 
Dave Abrahams
BoostPro Computing
http://www.boostpro.com