[boost] Re: FOREACH / C++ "for" proposal

From: David Abrahams (dave_at_[hidden])
Date: 2005-05-12 20:38:30

"Thorsten Ottosen" <nesotto_at_[hidden]> writes:

> | You can try it with
> |
> | template<class T> void begin( MyType<T> & t );
> |
> | and see that it will fail in a similar way. Also try
> |
> | template<class T> void begin( T & t );
> |
> | to see that it will succeed and deduce T as MyType<int> const.
> |
> | HTH.
>
> hm..you learn something new every day; I wasn't aware of the difference 
> between T& and UDT<T>&

It's not really a difference.

With 

     template <class T>
     void f(T&);

T can be deduced as anything, including const U for some U.

With

     template <class T>
     void f(something<T>&);

again T can be deduced as anything, including const U for some U.  But
there's no leeway to magically insert a const after "something<T>",
where there's no type parameter.

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com