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Re: Pre-RFC: a `module` keyword
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From:
Dan Book
Date:
January 24, 2022 21:16
Subject:
Re: Pre-RFC: a `module` keyword
Message ID:
CABMkAVWuTo6L8t692chWh3P0mPiGuphp+JN3Q92TVA3kj6tjMQ@mail.gmail.com
On Mon, Jan 24, 2022 at 4:13 PM Dan Book <grinnz@gmail.com> wrote:
> On Mon, Jan 24, 2022 at 3:58 PM Ovid via perl5-porters <
> perl5-porters@perl.org> wrote:
>
>> On Monday, 24 January 2022, 21:39:08 CET, Tomasz Konojacki <me@xenu.pl>
>> wrote:
>>
>> > > * Strict, warnings, utf8 source, signatures, and "no feature
>> 'indirect'" by default
>> >
>> > We can't make the "module" keyword visible without a feature flag. "use
>> > VERSION" will still be needed and that enables all the nice stuff
>> > anyway.
>>
>> My intention for the full RFC was:
>>
>> use feature 'module';
>>
>> > Well, apart from "use utf8". It's been decided that it's a bad
>> > default:
>> https://www.nntp.perl.org/group/perl.perl5.porters/2021/08/msg261164.html
>>
>> The change is lexically scoped, so ...
>>
>> use 5.38.0;
>>
>> module My::Module :version(.1) {
>> # use utf8 is only applied here in brand new code
>> }
>>
>> # use utf8 does not apply here
>>
>
> The reasons for it being a "bad default" are not elided by only being used
> for new code.
>
>
>> > > * :export is handled natively leaving the import() free for other uses
>> >
>> > I don't see why a new keyword is needed for that. If we want ':export'
>> > attribute (which is an interesting idea), it can be implemented without
>> > the "module" keyword. Perl already supports attributes on subs and we
>> > already have a few built-in ones (such as :const, :method etc.).
>>
>> There is no new keyword. Instead, this follows the Corinna "KIM syntax" (
>> https://ovid.github.io/articles/language-design-consistency.html) to
>> ensure language design consistency. :import is a modifier, not a keyword.
>> This RFC would introduce only one new keyword, `module`, and `:import`
>> doesn't exist without that feature.
>>
>
> I believe he was referring to adding the new keyword "module" for this,
> when it could be done more generally.
>
>
>> > The "package" keyword currently doesn't take attributes, but I think it
>> > can be changed. "package Foo :bar" is a syntax error, so it probably
>> > doesn't conflict with anything.
>>
>> Agreed, but I'm trying to create something which is entirely lexically
>> scoped in a new syntax to avoid complicating existing code.
>>
>
> Restricting it to a block is not required for it to be lexically scoped
> for new code - feature bundles already do this.
>
To add my own specificity to xenu's points: I think these are all good
ideas which don't require a new keyword or feature to implement.
-Dan
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