Re: Q: type ... is new String

["Yannick Duchêne (Hibou57)" <yannick_duchene@yahoo.fr>]

Le Mon, 04 Jun 2012 08:30:14 +0200, J-P. Rosen <rosen@adalog.fr> a écrit:

> Le 04/06/2012 07:58, Yannick Duchêne (Hibou57) a écrit :
>>    Minimum_Length : constant := <platform dependent>;
>>    Maximum_Length : constant := <platform dependent>;
>>
>>    subtype Index_Type is Natural range Minimum_Length .. Maximum_Length;
>>
>>    type Path_Type is new String (Index_Type);
>>    -- Unfortunately, this freeze the lower and upper bound, and the
>>    -- declaration below fails.
>>
>>    XYZ_Location : Path_Type := "..................."; -- Will fail.
> Why not:
> type Path_Type is array (Index_Type range <>) of Character;
>
> ?
> Reminder: There is nothing special to type String, you'll still have
> literals etc.

Good idea. I did not consider this one, may be due to the natural tendency  
of deriving from an already existing type with similar meaning.

While I'm OK with this idea and feel it good, I would not apply it,  
because I would prefer to derive from String. Ada lacks a way to narrow  
the allowed range of a derived array type.

-- 
“Syntactic sugar causes cancer of the semi-colons.” [1]
“Structured Programming supports the law of the excluded muddle.” [1]
[1]: Epigrams on Programming — Alan J. — P. Yale University