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From: Lawrence =?iso-8859-13?q?D=FFOliveiro?= <ldo@nz.invalid>
Newsgroups: comp.lang.ada
Subject: Re: In precision typing we trust
Date: Mon, 25 Aug 2025 21:10:12 -0000 (UTC)
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On Mon, 25 Aug 2025 10:19:50 +0200, Dmitry A. Kazakov wrote:

> On 2025-08-24 23:50, Lawrence D’Oliveiro wrote:
>>
>> Python not only has inheritance, it has full multiple inheritance
>> with C3 linearization.
> 
> No members are inherited.

    from enum import \
        Enum

    class MYENUM(int, Enum) :
        VAL1 = 1
        VAL3 = 3
    #end MYENUM

    print(isinstance(MYENUM.VAL1, int), isinstance(MYENUM.VAL1, MYENUM))

    True True

    print(MYENUM.VAL1 + 1)

    2

    print(MYENUM(3))

    MYENUM.VAL3

    print(MYENUM(2))

    ---------------------------------------------------------------------------
    ValueError                                Traceback (most recent call last)

    [detailed traceback omitted]

    ValueError: 2 is not a valid MYENUM

> Not to say that nothing is checked etc. Expecting that from an untyped
> language would be silly anyway.

Python is strongly typed.

> But in OO it is incorrect to inherit covariant methods with arguments in
> the out or in-out mode ...

That’s OK, because Python only has “in” mode.

>> It also has metaclasses. Because classes, like functions, are
>> first-class objects.
>
> A useless thing in an untyped language ...

Except Python is strongly typed.

> ... and in general one should first question what could be the
> purpose of a set of a set of types?

It does away with the need for generics and a separate compile-time
language for working with them. Instead, you use the same run-time
language as you would for everything else.

Also, this
<https://gitlab.com/ldo/python_topics_notebooks/-/blob/master/Uses%20For%20Metaclasses.ipynb>.