Re: Copy vector in Ada

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On Mon, 05 Nov 2012 21:18:17 +0100, Yannick Duchêne (Hibou57) wrote:

> Le Mon, 05 Nov 2012 19:42:57 +0100, Dmitry A. Kazakov  
> <mailbox@dmitry-kazakov.de> a écrit:
> 
>> On Mon, 05 Nov 2012 18:22:45 +0100, Yannick Duchêne (Hibou57) wrote:
>>
>>> Le Mon, 05 Nov 2012 10:20:44 +0100, Dmitry A. Kazakov
>>> <mailbox@dmitry-kazakov.de> a écrit:
>>>> There are lots of further questions about special treatment of copy
>>>> constructors, like whether one could introduce them later, e,g,  
>>>> promoting
>>>> limited types to non-limited
>>> Would make sense, with a derived type adding capabilities (similar  
>>> comment
>>> with unknown discriminant). The proof it would make sense is that in a
>>> package spec, you can change a limited to a non‑limited, without  
>>> breaking
>>> anything.
>>>
>>>> and demoting back.
>>> Back from non‑limited to limited? This one is not cool.
>>
>> But "constant T" is cool? Note that constant does just this and also
>> disallows any other mutators.
> 
> A constant is just an easy‑and‑quick function, that's not the same as an  
> object.

   procedure Foo (Object : in T);

here in T = constant T = immutable subtype of T = T - assignment - some
other operations.

> The result returned by a function has a target object, but is not  
> an object. At least, that's my personal model of a constant (is this model  
> wrong?).

What really matters is the type and the operations of the object, be it
run-time or compile-time one. Assignment is effectively disallowed on
immutable types and subtypes.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de