Re: Problems with Named Template Parameters

From: David Abrahams (abrahams_at_[hidden])
Date: 2001-05-23 15:57:11

----- Original Message -----
From: "Jeremy Siek" <jsiek_at_[hidden]>

> abraha> It looks like the code we have in iterator_adaptor_test.cpp for
testing the
> abraha> named template parameter technique is inadequate, since it only
tests one
> abraha> case where no default parameter values are used. It didn't reveal
the
> abraha> problem I'm having with GCC. Given this and the complexity of the
code I am
> abraha> tempted to roll back the feature until more people than just
Jeremy can
> abraha> understand it.
>
> I'd be ok with that, just let me know so I can make sure that I can update
> places where I use it.

I'd rather not resort to anything this drastic. If you'd prefer to write
more tests and documentation, that would be better I think!

> abraha> When using the named template parameter approach in a template, it
could get
> abraha> a bit unweildy because instead of writing e.g., ::value_type<T>
you need to
> abraha> write ::template value_type<T>. I think our documentation should
make
> abraha> mention of this and we should consider whether there are ways to
cut down
> abraha> the syntax.
>
> That's a good point. There are some alternatives that don't have this
> problem, like using separate wrappers for each parameter instead of
> nesting them.

I'm guessing that approach would be much easier to understand.

-Dave