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Re: [perl #134156] use feature ':all'

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From:
Dave Mitchell
Date:
June 3, 2019 08:52
Subject:
Re: [perl #134156] use feature ':all'
Message ID:
20190603085211.GF4761@iabyn.com
On Fri, May 31, 2019 at 11:55:15AM -0700, Diab Jerius (via RT) wrote:
> The documentation describes its use only in the negative, e.g. when explaining
> how 
> 
>   use v5.10.0;
> 
> works via
> 
>   no feature ':all';
>   use feature ':5.10';
> 
> Is there a reason that one should not use ':all' positively? As in
> 
>   use feature ':all';

It defeats the whole purpose of feature.pm - which is to allow us to
add new features to perl which are not backwards compatible.

If people start adding "use feature ':all'" to their programs, then their
programs may break on future releases of perl. If lots of people start
adding it, then we'll be told that we can't add a new feature to perl
because it would break too many existing modules that people reply on.  So
we'd have to introduce "reluctant" features which aren't enabled by
':all'; then we'd have to add ':really_all', then that would be abused,
and so the cycle continues.

-- 
The Enterprise is involved in a bizarre time-warp experience which is in
some way unconnected with the Late 20th Century.
    -- Things That Never Happen in "Star Trek" #14

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