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Date: Thu, 24 Mar 2022 10:34:53 -0600
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To: Pierre <pierre-php@processus.org>
Cc: Larry Garfield <larry@garfieldtech.com>, php internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] Typed constants revisited
From: mbniebergall@gmail.com (Mark Niebergall)

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Pierre,

On Thu, Mar 24, 2022 at 9:20 AM Pierre <pierre-php@processus.org> wrote:

> Le 24/03/2022 =C3=A0 16:06, Mark Niebergall a =C3=A9crit :
> > So you are correct, the const value does have a value that has a type,
> but
> > there is no way to enforce which type the value is or to use const with
> > inheritance, which is part of the bigger picture here.
>
> That was exactly my point: the type could simply implicitely be the one
> of the original value.
>
> Then the engine just has to use the existing covariance/contravariance
> rules for type checks based upon the guessed value type. This would fix
> the type safety issue you are referring to.
>

I'd rather not use the "guessed value type" in code, that tends to lead to
bugs: guessing =3D bugs. Explicitly declaring the type avoids the pitfalls =
of
guessing and ensures code predictability. It also comes with added
benefits, including self-documenting code, defined inheritance requirements
(the way you describe would have BC breakage), and (for some IDEs) type
hinting.

Of note, many other languages already have typed constants. Yes this is the
"everyone else is doing it" argument, but they had their valid reasons.
Some are strong typed languages, others are not. See:

- Go: https://go.dev/blog/constants
- HVVM: https://docs.hhvm.com/hack/classes/type-constants
- C: https://fresh2refresh.com/c-programming/c-constants/
- C++: https://en.cppreference.com/w/c/language/const
- C#:
https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/=
const


>
> --
>
> Regards
>
>

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