Re: Another, potentially nastier problem with dereferenceable and the iterator_helpers

From: Dave Abrahams (abrahams_at_[hidden])
Date: 2000-06-13 15:54:22

--- In boost_at_[hidden], Lois Goldthwaite <loisg_at_o...> wrote:
> Isn't the value_type supposed to be something which is passed by 
value? As
> opposed to a reference, which would permit operations on the value 
in the
> container? If I say
> 
>     const T t1;
>     T t2 = t1;
> 
> isn't that legal?

Well, we're talking about an iterator's value_type, not a container's 
value_type, which may be two different things. Anyway, who said the 
value_type is supposed to be anything in particular? I don't get any 
help from the standard on this, really. The expressions *p and *p++ 
are supposed to be convertible to the value_type. Also, for output 
iterators you're supposed to be able to write *p = t, where t is of 
type value_type. When you get to ForwardIterator requirements, you 
see that you need to be able to form a referenct to the value_type. 
That's about it, though.

-Dave