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

From: Eric Niebler (eric_at_[hidden])
Date: 2008-03-20 17:53:22

Larry Evans wrote:
> What about recording the arity *with* the tag instead of in
> the expression associated with the tag?  IOW, instead of:
> 
>    expr<Tag,Args,Arity>
> 
> have:
> 
>    expr<tag_arity<Tag,Arity>,Args>
> 
> Why?  Well, it directly associates the arity with the Tag instead
> of with the expression.  After all, sin(X) is not expressed
> as sin(x,1). [or in lisp terms, (sin x) is not expressed as
> (sin x 1) ].

What problem does that solve?

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