[v3] PATCH: PR 20599 (variadic templates, take two) (4/4)

[Doug Gregor]

On 9/20/06, Paolo Carlini <pcarlini@suse.de> wrote:
> Douglas Gregor wrote:
>
> > This is part 4 of 4. It contains changes to libstdc++'s TR1
> > implementation to make full use of variadic templates, eliminating
> > all of the preprocessor metaprogramming that we're using now.
>
> +  // Define a large number of placeholders. There is no way to
> +  // simplify this with variadic templates, because we're introducing
> +  // unique names for each.
> +  namespace placeholders { namespace {
> +    _Placeholder<1> _1;
[snip gazillions of placeholders]
> +  } }
>
>
> Certainly a minor nit, but I'm curious about this issue: are there any
> concrete plans to address it? Seems strange to have it in the final
> standard, I never saw something similar before...

I don't know of any plans to address this issue. TR1 basically just
says that there are objects _1, _2, _3, etc. (up to _10, at least).
Since each has a unique name, we'd need some kind of language solution
to get rid of the repetition. It doesn't fit into variadic templates
at all; I can't even think of anywhere it does fit.

  Doug