Re: Record operations (Algebraic Data Types and printing)

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

On 2018-10-10 20:13, G. B. wrote:
> Dmitry A. Kazakov <mailbox@dmitry-kazakov.de> wrote:
>> On 2018-10-10 00:20, Randy Brukardt wrote:
> 
>>> What package? We're talking about (in part) the default representation for a
>>> type.
>>
>> What have T'Image and T'Value to do with the type representation?
> 
> I suppose that if “for a type” here is to mean given type T one may apply
> T’Image to an object (directly), then the result represents an object of
> type T. Not in the sense of representation clauses, but in the sense of
> printed value.

It does not. It represents an object of the type String. The value of 
the string may correspond to an object of the type T or can be used to 
create an object of the type T. Corresponds /= represents. Represents 
means substitutable.

Image/Value could represent T if String were a sub-/supertype of T. This 
is not possible in Ada. The litmus test is inheritance of the interface 
of T. If you could write something like this

    1'Image + 2 = "3"

You could say that 1'Image represents Integer'(1). And "3" represents 
Integer'(3).

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