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

Subject: Re: [boost] [range] adaptors vs. rvalue to lvalue& binding
From: Arno Schödl (aschoedl_at_[hidden])
Date: 2012-03-23 16:28:31

Hello,

>
>  - 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.

If boost::sort is supposed to be chainable (which seems a good idea), then let's not start with adaptors. We already need a solution for

boost::sort( std::vector() );

If the solution is

template<typename Range>
boost::sort( Range && );

then in

boost::sort( boost::adaptors::reverse( std::vector() ) );

reverse should probably derive mutable iterators from mutable rvalues, so would have signature:

reverse( Range && );

So the policy is:

All range functions and adaptors take all ranges by &&, and range::iterator<rvalue>::type is mutable, in particular for adaptors. To chain from a function, return via std::forward<Range>.

Problem solved?

Arno

--
Dr. Arno Schödl | aschoedl_at_[hidden]
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