From: Larry Evans (cppljevans_at_[hidden])
Date: 2008-03-21 16:24:02
On 03/20/08 20:17, Eric Niebler wrote:
> Larry Evans wrote:
>> However, I'd imagine some people would want
>> this restricted to just two elements, which could be
>> done with something like:
>> And now, if size<Args>::value is
>> restricted to the Arity in
>> tag_arity<shift_right,Arity> then it
>> would be restricted to 2.
> Users may very well want to restrict tag::plus to arity 2 *in their
> domain*, but they shouldn't be foisting that decision on other consumers
> of Proto.
Good point. I agree. then just define:
template<class Tag,int Arity,class Domain=default_domain>
which has no restrictions on arity, but it allow the user to
specify restrictions by specializaing on Domain.
> The best way to ensure that expressions have the arity you
> expect is to encode that in the grammar for your domain, and check it
> with proto::matches.
Like in the attached?
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