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Re: feature.pm proposal
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From:
Father Chrysostomos
Date:
October 30, 2011 22:59
Subject:
Re: feature.pm proposal
Message ID:
318D8E68-A8FC-4CE5-A6DD-064933E26E11@cpan.org
Aristotle wrote:
> What you really want to happen is for provenance to be remembered. In
> case of
>
> use strict;
> use 5.010;
>
> you want strictures to be enabled because they were enabled explicitly.
> But in case of
>
> use 5.012;
> use 5.010;
>
> you want them disabled, because they were only implicitly enabled by way
> of a version feature bundle.
>
> I’d also argue by the same token that
>
> use feature 'unicode_strings';
> no 5.014;
>
> should leave `unicode_strings` enabled.
Unfortunately, no 5.014 already means something else.
$ perl5.15.4 -M-5.014
Perls since v5.14.0 too modern--this is v5.15.4, stopped.
BEGIN failed--compilation aborted.
I think making
use feature 'unicode_strings';
use 5.010;
leave the feature enabled might be going a bit to far. It makes it
harder to document. If we say that use-version enables the feature
bundle for that version, then we have to go through contortions to
explain that it doesn't really.
>
>
> We don’t have a mechanism to do that.
>
> I’m not sure how feasible it would be to retrofit.
>
> Though on reflection it might even be very easy, since I think only
> feature.pm needs some extra code – if the enabling of strictures is
> retroactively re-cast as a feature, it might even not require touching
> anything else. I’m not sure.
strict would have to be remembered in two places. "use strict" would
have to turn on strict the usual way *and* turn off the strict
features, so that feature.pm knows not to disable strict. That is
quite doable.
If $[ is to be disabled under 5.16, then I think we do need something
like that. $[ will become a part of the 5.14 bundle (and lower
versions). "use v5.16" will disable it, as not being part of the
5.16 bundle.
Leon Timmermans suggested that strictures become fatal warnings. I
could never figure out a way to stop "no warnings" from turning off
strict, though. Maybe it could be based on this somehow.
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