Re: Wide_[Wide_]Character

[Dale Stanbrough <MrNoSpam@bigpoop.net.au>]

Georg Bauhaus wrote:

> package Standard specifize 'Size of Wide_Wide_Character,
> 
>         type Wide_Wide_Character is
>             (nul, soh ... Hex_7FFFFFFE, Hex_7FFFFFFF);
>         for Wide_Wide_Character'Size use 32;

thanks, I hadn't seen that.

> Annex B has some hints as to the internal representation:
> 
> 43.a/2 Discussion: The C types wchar_t and char16_t seem to be the same.
>    However, wchar_t has an implementation-defined size, whereas
>    char16_t is guaranteed to be an unsigned type of at least 16 bits.
>    Also, char16_t and char32_t are encouraged to have UTF-16 and UTF-32
>    representations; that means that they are not directly the same as
>    the Ada types, which most likely don't use any UTF encoding.

This seems to be in reference to the Ada C.Interfaces type, not 
Wide_Wide_Character.


> Isn't this just like the RM not specifying the bit layout of
> numeric objects?

I'm not sure what the point of Wide_Wide_Character is if not to deal 
with Unicode (or ISO-10646:2003).

You could invent your own 32 bit Character code (or use the one the 
vendor gives you), but playing in your own backyard doesn't seem very 
productive. To me the only point is if it implements the code.


Dale

-- 
dstanbro@spam.o.matic.bigpond.net.au