Re: Ada and Unicode

[Thomas <fantome.forums.tDeContes@free.fr.invalid>]

In article <s5k0ai$bb5$1@dont-email.me>, "J-P. Rosen" <rosen@adalog.fr> 
wrote:

> Le 19/04/2021 à 15:00, Luke A. Guest a écrit :
> > They're different types and should be incompatible, because, well, they 
> > are. What does Ada have that allows for this that other languages 
> > doesn't? Oh yeah! Types!
> 
> They are not so different. For example, you may read the first line of a 
> file in a string, then discover that it starts with a BOM, and thus 
> decide it is UTF-8.

could you give me an example of sth that you can do yet, and you could 
not do if UTF_8_String was private, please?
(to discover that it starts with a BOM, you must look at it.)


> 
> BTW, the very first version of this AI had different types, but the ARG 
> felt that it would just complicate the interface for the sake of abusive 
> "purity".

could you explain "abusive purity" please?

i guess it is because of ASCII.
i guess a lot of developpers use only ASCII in a lot of situation, and 
they would find annoying to need Ada.Strings.UTF_Encoding.Strings every 
time.

but I think a simple explicit conversion is acceptable, for a not fully 
compatible type which requires some attention.


the best would be to be required to use ASCII_String as intermediate, 
but i don't know how it could be designed at language level:

UTF_8_Var := UTF_8_String (ASCII_String (Latin_1_Var));
Latin_1_Var:= String (ASCII_String (UTF_8_Var));

and this would be forbidden :
UTF_8_Var := UTF_8_String (Latin_1_Var);

this would ensures to raise Constraint_Error when there are somme 
non-ASCII characters.

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