`meta` module experimental warnings

[Paul "LeoNerd" Evans]

The `meta` module continues its experimentation. The documentation does
say "it's experimental", but likely it needs some actual runtime
warnings adding to that effect.

It seems the usual style would be for various functions and initial
access points to print warnings in some category that can be silenced,
allowing the developer to accept the experimental nature of it.

The question becomes: What should that warning category be? Two obvious
thoughts come to mind:

* It could be `meta::experimental`, as its own module:

use meta;
no warnings 'meta::experimental';
...

* It could borrow an area of core and be `experimental::meta`

use meta;
no warnings 'experimental::meta';

In this latter idea, it would casually lead users to think that they
could combine the whole lot by perhaps doing

use experimental 'meta';

However, as experimental.pm currently stands, that would not work. It
would have to be modified to recognise that "meta" is the name of a
brand new module that it ought to load first, to then disable the
warning category. I'm not entirely sure about the feel of this, as it
starts to conflate the idea of simple named features (as per
`use feature ...`) and entire new modules - which in any case for older
perls would just be installed from CPAN in the usual manner for
external modules.

Likely the first idea is best.

Does anyone have any thoughts here?

--
Paul "LeoNerd" Evans

leo...@leonerd.org.uk | https://metacpan.org/author/PEVANS
http://www.leonerd.org.uk/ | https://www.tindie.com/stores/leonerd/

[G.W. Haywood]

Hi there,

On Thu, 4 Jan 2024, Paul "LeoNerd" Evans wrote:

> use meta;
> no warnings 'meta::experimental';
> ...

This seems by far the more natural to me.

--

73,
Ged.

[Philippe Bruh:%at (BooK)]

On Thu, Jan 04, 2024 at 05:41:34PM +0000, Paul "LeoNerd" Evans wrote:
>
> The question becomes: What should that warning category be? Two
> obvious thoughts come to mind:
>
> * It could be `meta::experimental`, as its own module:
>
> use meta; no warnings 'meta::experimental';

This has the benefit of being below the "meta" namespace. Everything
is obvious.

> * It could borrow an area of core and be `experimental::meta`
>
> use meta; no warnings 'experimental::meta';

The "experimental::" namespace seems to be mostly used by experimental
features so far.

> In this latter idea, it would casually lead users to think that they
> could combine the whole lot by perhaps doing
>
> use experimental 'meta';

The current use-case for a `use experimental` line (e.g. `use
experimental 'signatures'`) is that it will be removed once the feature
is not experimental anymore in the declared bundle.

A piece of code using an experimental feature will evolve as such:

use v5.34;
use feature 'signatures';
no warnings 'experimental::signatures';

Which can be shortened to:

use v5.34;
use experimental 'signatures';

Once signatures are not experimental, it shrinks down to:

use v5.36;

So the `use experimental` line is meant to disappear eventually.


The `meta` modules is meant to be always be loaded explicitely, and is
not a feature. With an implicit `use meta`, once the experimental
warnings are dropped, one would have to replace `use experimental
'meta';` with `use meta;`. Doesn't look like much gain.

The evolution of your last proposal would look something like:

use v5.40;
use experimental 'meta';

becoming, once not experimental any more:

use v5.42;
use meta;

As opposed to:

use v5.40;

use meta;
no warnings 'meta::experimental';

becoming:

use v5.42;
use meta;

> Likely the first idea is best.

I agree with you.

--
Philippe Bruhat (BooK)

Treat those you outrank well... you never know when they will outrank you.
(Moral from Groo #7 (Image))