Re: [boost] Pervasive dependency upon mpl::bool_

Subject: Re: [boost] Pervasive dependency upon mpl::bool_
From: Rob Stewart (robertstewart_at_[hidden])
Date: 2014-06-02 05:03:52

On June 1, 2014 5:30:12 PM EDT, Peter Dimov <lists_at_[hidden]> wrote:
>Jonathan Wakely wrote:
>
>> Would it be possible to define true_ and false_ with a lot less code?
>
>Possibly. The problem is that mpl::bool_ is owned by MPL. It can impose
>all 
>sorts of (potentially changing, although this is not an issue at the
>moment) 
>requirements on them. None of those are actually needed by people doing
>tag 
>dispatching, but we can't just kidnap mpl::true_ and mpl::false_ and
>decree 
>that they shall henceforth live in Core. 

Put a few pieces into core and change MPL to use or derive from them. For example, mpl:: true_type can derive from a new boost::true_type (which could be an alias for std:: true_type). New and refactored code can use the latter, while legacy code can continue to use the former.

___
Rob

(Sent from my portable computation engine)