Re: [boost] [Review] Type Traits Extension by Frederic Bron - Review summary and decision

Subject: Re: [boost] [Review] Type Traits Extension by Frederic Bron - Review summary and decision
From: Max Sobolev (macsmr_at_[hidden])
Date: 2011-04-22 08:49:07

On 21.04.2011 23:13, Stewart, Robert wrote:
> Remember that "has_" implies ownership or inherent characteristic which doesn't apply to a namespace scope operator.

Class must have only intrinsic member functions, without which it 
doesn't working. Extended part of interface defines out of class body 
(perhaps in a separate module) in the same namespace, in terms of 
intrinsic member functions. This decrease coupling of code.

(This C++ Software Construction approach was clearly described and 
proposed in Czarnecki/Eisenecker "Generative Programming". - S.Meyers 
agree; H.Sutter agree; D.Abrahams :) agree.)

Consider Barton/Nackman trick as it presents in Boost.Operators library: 
boost::equality_comparable<T> require from T operator < is being defined 
(as member or free operator function, doesn't matter). Operators >, <=, 
 >= are generated automatically as free operator functions due to 
inheritance.

But there is no difference between 4 operators <, >, <= and >= from 
point of view its meaning and "status": they all makes interface of 
class T. Operators >, <=, >= aren't second class citizens, even if 
operator < is define as member operator function.

-- 
- Do you speak English? Мужик с глубоким вздохом: - Yes I do. А хули толку?