Re: user-defined types and basic_string

[Benjamin Kosnik <bkoz at redhat dot com>]

> User-defined constructors are not permitted in PODs.
> I think we don't really need the conversion function.
> To the above should just read
> 
>    struct character
>    {
>       unsigned short value;
>    };
> 
> Or, I think we could just put in a template surrogate for fundamental
> types:
> 
>   template<typename _Tp>
>     struct character
>     {
>        T value;
>     };
> 
> along with the two functions:
> 
>   template<typename T>
>     inline bool 
>     operator==(character<T> lhs, character<T> rhs)
>     { return lhs.value == rhs.value; }
> 
>   template<typename T>
>      inline bool 
>      operator<(character<T> lhs, character<T> rhs)
>      { return lhs.value < rhs.value; }

Cool. I stand corrected.

> |       // NB: this type should be bigger than char_type, so as to
> |       // properly hold EOF values in addition to the full range of
> |       // char_type values.
> |       typedef unsigned long  	int_type;
> 
> This makes the assumption that range(unsigned long) is a strict
> superset of range(unsigned short).  If we were going to assume that,
> why not just use "int" as int_type?

Could do. (Unsigned int though if value_type == unsigned short, oui?)

It seems int_type is one of the points where the generic templates start
to fall down...

> From your yesterday mail, I thought you were talking of a generic way
> to define customization points of char_traits for users.
> 
> Actually, I'm not convinced that we should make a big deal about
> defining a specialization for std::char_traits<>.  Defining such a
> specialization just amonts to define a trait class in one's own
> namespace, but then there is no need to wrap the fundamental types in
> a struct.  Thoughts?

I'm not quite sure I follow you. Can you give examples in C++? 

-benjamin