Re: [boost] [proto] design of expr<>

From: Eric Niebler (eric_at_[hidden])
Date: 2008-03-20 19:10:50

Larry Evans wrote:
> I don't think it solves any problem that can't
> already be solved, but it makes the solution
> clearer.  It's clearer because the arity
> is associated with the tag *not* the
> expression.  The arity of a tag does not depend
> on the expression; so, it should not be in
> the expression.  Instead the arity of the tag
> determines the expression validity.

Sorry, but that's backwards. Tags don't have arities, expressions do. 
The arity of tag::function could be anything. The arity represents the 
number of children of an expression node. So the arity is a very real 
part of an expression.

-- 
Eric Niebler
Boost Consulting
www.boost-consulting.com