Can use feature ':all' be removed or improved?

[book]

As discussed in PSC meeting #179, the Perl Steering Council would like use feature ':all' to go away if possible.

It was never a good idea anyway, and has become untenable with the introduction of feature flags like indirect and bareword_filehandles, which disable features that are considered obsolete. We expect to have many more of those in the future (v5.42 is going to include apostrophe_as_package_separator and smartmatch).

Since the purpose of those features is to be disabled rather than enabled by default, a simple toggling of all features (on or off) is a nonsensical request.

Usage seems to be very limited on CPAN. https://grep.metacpan.org/search?size=20&_bb=456911623&q=use+feature+.*%3Aall&qd=&qft=&qifl= reports:

Result: found 21 distributions and 60 files matching your query !

And in core, it's only used in tests (and documentation for use feature itself):

$ git grep -l 'use feature.*:all'
lib/B/Deparse.t
lib/feature.pm
regen/feature.pl
t/comp/require.t
t/op/svleak.t

Maybe anothe option for :all would be to only enable the "positive" features
(experimental and enabled in the current version of Perl)? This would have
the benefit of being backwards compatible, and would solve the "nonsensical"
part that re-enables deprecated features. I don't doubt it introduces different issues.

[jkeenan]

While I share your sentiments, I think that this is a policy discussion which ought to first take place on the mailing list. Suggesting that a feature either be removed or improved is a bit too open-ended for treatment as an Issue.

[Leont]

Usage seems to be very limited on CPAN. https://grep.metacpan.org/search?size=20&_bb=456911623&q=use+feature+.*%3Aall&qd=&qft=&qifl= reports:

It seems 18 out of 20 cases are from just two authors. The other two are both meta-pragmas, and in one of these two is used in the documentation only.

[tonycoz]

I have code that uses the :all bundle to switch all features off so I can get just the features from a versioned bundle, since use feature ":5.32" does not turn off "indirect" etc, i.e.:

# in a "sane defaults" module import():
feature->unimport(":all");
feature->import(":5.32");

Inline I could just do:

use v5.32;

but that won't work from a sane defaults module import method.

[Grinnz]

Perhaps we need a better way for things using feature.pm directly to cleanly set a feature bundle.