Re: [boost] RE: Submission: typelist

From: David Abrahams (david.abrahams_at_[hidden])
Date: 2001-11-27 19:21:07

----- Original Message -----
From: "Jonathan H Lundquist" <jhl_at_[hidden]>
To: <boost_at_[hidden]>
Sent: Tuesday, November 27, 2001 7:05 PM
Subject: [boost] RE: Submission: typelist

> Personally, I prefer type2type, simply because I already use the name
> 'identity' for the following:
>
> template<typename T>
> struct identity : public unary_function<T, T> {
>    const T& operator()(const T& x) const throw()
>    {
>       return x;
>    }
> };

Firstly, runtime and compile-time behavior are different domains, and so may
well live in different namespaces.

Secondly, Aleksey and Emily were just discussing a hybrid:

template<typename T>
struct identity : public unary_function<T, T> {
   const T& operator()(const T& x) const throw()
   {
      return x;
   }
   typedef T type;
};

Now identity works at runtime and at compile-time. Cute, or perhaps... MOST
NEFARIOUS!!

-Dave