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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: In precision typing we trust
Date: Wed, 27 Aug 2025 09:39:59 +0200
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On 2025-08-27 02:13, Lawrence D’Oliveiro wrote:
> On Tue, 26 Aug 2025 09:59:48 +0200, Dmitry A. Kazakov wrote:
> 
>> On 2025-08-25 23:13, Lawrence D’Oliveiro wrote:
>>>
>>> On Mon, 25 Aug 2025 22:09:14 +0200, Dmitry A. Kazakov wrote:
>>>
>>>> The question remains why should I need to instantiate it beyond
>>>> declaring an object of?
>>>
>>> Because in Python a class, like all objects, is created at runtime, not
>>> compile time.

Not true, because in Python there exist types created before the 
interpreter starts. But it is irrelevant.

In Ada types can be created dynamically:

    declare
       type T is ...
    begin
       ...
    end;

The difference is that the semantics of such types is static in Ada and 
undefined in Python.

> No. In Ada, C or C++, definitions are not “executable”. They do not
> “create objects”.

Of course they are executable. They may or may not produce objects.
> Think of a function that is a class factory: each time it is called, it
> creates and returns a new class as the function result. This depends
> crucially on a) classes as first-class objects, and also b) lexical
> binding.
> 
> Can you do that in Ada, C or C++? No you cannot.

Yes I can. It is actively used in software design. E.g. for plug-ins, 
library implementing a driver derives  a type from the base type.

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