[pm-h] Bitten by "Experimental keys on scalar is now forbidden" on perl 5.23.X - How not to use keys!

[Robert Stone]

Greetings,

I've just released a heavily refactored version of my WWW::LogicBoxes
module to cpan (
http://search.cpan.org/dist/WWW-LogicBoxes/lib/WWW/LogicBoxes.pm), Huzzahs
are in order!

However, cpan testers pointed out an issue to me:

Experimental keys on scalar is now forbidden at
/tmp/loop_over_bdir-8387-8qtZ5O/WWW-LogicBoxes-1.0.1-syf1_3/blib/lib/WWW/LogicBoxes/Role/Command/Raw.pm
line 165.


Looking at the perldiag documentation:

*5.22*

keys on reference is experimental
(S experimental::autoderef) keys with a scalar argument is experimental and
may change or be removed in a future Perl version

*5.23*

Experimental %s on scalar is now forbidden
(F) An experimental feature added in Perl 5.14 allowed each, keys, push,
pop, shift, splice, unshift, and values to be called with a scalar
argument. This experiment is considered unsuccessful, and has been removed.
The postderef feature may meet your needs better.


*So, this code will now cause compilation failures:*

my $hashref = {
    key => 'value',
};

for my $key ( *keys $hashref* ) {
    print $key . "\n";
}

*And should instead be:*

for my $key ( *keys %{ $hashref }* ) {
    print $key . "\n";
}

Good times!

I have to admit that the later is more explicit but I kinda feel like this
violated the spirit of perl's "Do what I mean."  Is there any more
backstory, or can anyone else put forward additional reasons as to why this
functionality is being removed?

Best Regards,
Robert Stone
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