[boost] Re: is_class

From: Howard Hinnant (hinnant_at_[hidden])
Date: 2003-02-14 19:17:19

On Friday, February 14, 2003, at 06:33  PM, Daniel Frey wrote:

> A last general question: It seems to me that the boost type-traits are 
> a
> mixture of two very different concepts: One concept is that of a 
> classic
> "utility library". This means, that it provides things I can use when I
> like, but they don't affect my code in general. The other concept is 
> that
> of a "framework". In order to use is_union, has_* and some other
> functions, I have to flag my classes, that means I have to write my 
> code
> in a "boost-friendly" way in order to make it work. I think that it 
> might
> be worth to make a very clear distinction between these two parts.
> Comments?

In my opinion, the intent from day one was to view the type traits lib 
as a utility library, and not a framework.  The fact that we couldn't 
make is_union work was viewed as a failure in the implementation that  
would probably need compiler support to make it work right.  Having you 
specialize your class for is_union was viewed as a workaround for the 
failing of the implementation, not as a well designed interface.

I agree with you that this is an important distinction to make.  As 
proposed to the standards committee, the interface needs to be very 
clear.

-Howard