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From: "David Abrahams" <abrahams@mediaone.net>
Newsgroups: comp.std.c++
Subject: Re: All I want for Christmas (was C++0x)
Date: Sat, 19 May 2001 18:48:53 GMT
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"Paul Mensonides" <pmenso57@home.com> wrote in message
news:153N6.24719$p33.428418@news1.sttls1.wa.home.com...
> Hey, Andrei, what do you think of some type of templated parameter list?
For
> example...
>
> template<class T> class SomeCollection {
>     private:
>         unsigned m_size;
>         T* m_v;
>     public:
>         template<class U, V(...)> void for_each(U (T::* pm)(V), V) {
>             for (int i = 0; i < m_size; ++i) {
>                 m_v[i].*pm(#V); // #V indicates values rather than type
>             }
>         }
> };

Something like this is on my big-10 list of missing template features. It is
a sad fact of C++ programming that many idioms require the writing of
forwarding functions. Doing this with templates can get really frustrating
when they need overloads to deal with all the different combinations.
Usually, I have to resort to C++ code generation (using, e.g., Python) just
to ensure I don't make any mistakes. I rather like your syntax, too, though
it should be possible to lose the pound sign (why not just declare v of type
V?) and the parens around the ellipsis (they seem to indicate a function).

-Dave

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