Provided by: libperl-critic-pulp-perl_96-1_all bug

NAME

       Perl::Critic::Policy::Compatibility::PerlMinimumVersionAndWhy - explicit Perl version for
       features used

DESCRIPTION

       This policy is part of the "Perl::Critic::Pulp" add-on.  It requires that you have an
       explicit "use 5.XXX" etc for the Perl syntax features you use, as determined by
       "Perl::MinimumVersion".

           use 5.010;       # the // operator is new in perl 5.010
           print $x // $y;  # ok

       If you don't have the "Perl::MinimumVersion" module then nothing is reported.  Certain
       nasty hacks are used to extract reasons and locations from "Perl::MinimumVersion".

       This policy is under the "compatibility" theme (see "POLICY THEMES" in Perl::Critic).  Its
       best use is when it picks up things like "//" or "qr" which are only available in a newer
       Perl than you meant to target.

       An explicit "use 5.xxx" can be a little tedious, but has the advantage of making it clear
       what's needed (or supposed to be needed) and it gives a good error message if run on an
       older Perl.

   Disabling
       The config options below let you limit how far back to go.  Or if you don't care at all
       about this sort of thing you can always disable the policy completely from your
       ~/.perlcriticrc file in the usual way (see "CONFIGURATION" in Perl::Critic),

           [-Compatibility::PerlMinimumVersionAndWhy]

   MinimumVersion Mangling
       Some mangling is applied to what "Perl::MinimumVersion" normally reports (as of its
       version 1.28).

       ·   A multi-constant hash with the "constant" module is not reported, since that's covered
           better by Compatibility::ConstantPragmaHash.

       ·   Module requirements for things like "use Errno" are dropped, since you might get a
           back-port from CPAN etc and the need for a module is better expressed in a
           distribution "prereq".

           But pragma modules like "use warnings" are still reported.  They're normally an
           interface to a feature new in the Perl version it comes with and can't be back-ported.
           (See "OTHER NOTES" below too.)

   MinimumVersion Extras
       The following extra checks are added to "Perl::MinimumVersion".

       5.12 for
           ·   new "keys @array", "values @array" and "each @array"

       5.10 for
           ·   "qr//m", since "m" modifier doesn't propagate correctly on a "qr" until 5.10

           ·   "-e -f -x" stacked filetest operators.

           ·   "pack()" new "<" and ">" endianness.

           ·   new "UNIVERSAL.pm" method "DOES()"

       5.8 for
           ·   new "word [newline] =>" fat comma quoting across a newline

               For earlier Perl "word" ended up a function call.  It's presumed such code is
               meant to quote in the 5.8 style, and thus requires 5.8 or higher.

           ·   "eval '#line ...'" with "#line" the very first thing

               In earlier Perl a "#line" as the very first thing in an "eval" doesn't take
               effect.  Adding a blank line so it's not first is enough.

           ·   "pack()" new "F" native NV, "D" long double, "i" IV, "j" UV, "()" group, "[]"
               repeat count

       5.6 for
           ·   new "exists &subr", "exists $array[0]" and "delete $array[0]"

           ·   new "0b110011" binary number literals

           ·   new "open(my $fh,...)" etc auto-creation of filehandle

           ·   "syswrite()" length parameter optional

           ·   "Foo->$method" no-args call without parens

               For earlier Perl a no-args call to a method named in a variable must be
               "Foo->$method()".  The parens are optional in 5.6 up.

           ·   "pack()" new "Z" asciz, "q","Q" quads, "!" native size, "/" counted string, "#"
               comment

       5.005 for
           ·   new "Foo::Bar::" double-colon package name quoting

           ·   new "my ($x, undef, $y) = @values", using "undef" as a dummy in a "my" list

       5.004 for
           ·   new "use 5.xxx" Perl version check through "use".  For earlier Perl it can be
               "BEGIN { require 5.000 }" etc

           ·   new "__PACKAGE__" special literal

           ·   new "foreach my $foo" lexical loop variable

           ·   new "$coderef->()" call with "->"

           ·   new "sysseek()" builtin function

           ·   "pack()" new "w" BER integer

           ·   new "UNIVERSAL.pm" with "VERSION()", "isa()" and "can()" methods

       "pack()" and "unpack()" format strings are only checked if they're literal strings or
       here-documents without interpolations, or "." operator concats of those.

       The "qr//m" report concerns a misfeature fixed in perl 5.10.0 (see perl5101delta).  In
       earlier versions a regexp like "$re = qr/^x/m" within another regexp like "/zz|$re/" loses
       the "/m" attribute from $re, changing the interpretation of the "^" (and "$" similarly).
       Forms like "(\A|\n)" are a possible workaround, though are uncommon so may be a little
       obscure.  "RegularExpressions::RequireLineBoundaryMatching" asks for "/m" in all cases so
       if think you want that then you probably want Perl 5.10 or up for the fix too.

   "Modern::Perl"
       "use Modern::Perl" is taken to mean Perl 5.10.  This is slightly experimental and in
       principle the actual minimum it implies is forever rising, and even now could be more, or
       depends on it date argument scheme.  Maybe if could say its actual current desire then an
       installed version could be queried.

CONFIGURATION

       "above_version" (version string, default none)
           Set a minimum version of Perl you always use, so that reports are only about things
           higher than this and higher than what the document declares.  The value is anything
           the "version.pm" module can parse.

               [Compatibility::PerlMinimumVersionAndWhy]
               above_version = 5.006

           For example if you always use Perl 5.6 and set 5.006 like this then you can have "our"
           package variables without an explicit "use 5.006".

       "skip_checks" (list of check names, default none)
           Skip the given MinimumVersion checks (a space separated list).  The check names are
           shown in the violation message and come from "Perl::MinimumVersion::CHECKS".  For
           example,

               [Compatibility::PerlMinimumVersionAndWhy]
               skip_checks = _some_thing _another_thing

           This can be used for checks you believe are wrong, or where the compatibility matter
           only affects limited circumstances which you understand.

           The check names are likely to be a moving target, especially the Pulp additions.
           Unknown checks in the list are quietly ignored.

OTHER NOTES

       "use warnings" is reported as a Perl 5.6 feature since the lexically-scoped fine grain
       warnings control it gives is new in that version.  If targeting earlier versions then it's
       often enough to drop "use warnings", ensure your code runs cleanly under "perl -w", and
       leave it to applications to use "-w" (or set $^W) if they desire.

       "warnings::compat" offers a "use warnings" for earlier Perl, but it's not lexical, instead
       setting $^W globally.  In a script this might be an alternative to "#!/usr/bin/perl -w"
       (per perlrun), but in a module it's probably not a good idea to change global settings.

       The "UNIVERSAL.pm" methods "VERSION()", "isa()", "can()" or "DOES()" might in principle be
       implemented explicitly by a particular class, but it's assumed that's not so and that any
       call to those requires the respective minimum Perl version.

SEE ALSO

       Perl::Critic::Pulp, Perl::Critic

       Perl::Critic::Policy::Modules::PerlMinimumVersion, which is similar, but compares against
       a Perl version configured in your ~/.perlcriticrc rather than a version in the document.

       Perl::Critic::Policy::Modules::RequirePerlVersion

HOME PAGE

       <http://user42.tuxfamily.org/perl-critic-pulp/index.html>

COPYRIGHT

       Copyright 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017 Kevin Ryde

       Perl-Critic-Pulp is free software; you can redistribute it and/or modify it under the
       terms of the GNU General Public License as published by the Free Software Foundation;
       either version 3, or (at your option) any later version.

       Perl-Critic-Pulp is distributed in the hope that it will be useful, but WITHOUT ANY
       WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
       PURPOSE.  See the GNU General Public License for more details.

       You should have received a copy of the GNU General Public License along with Perl-Critic-
       Pulp.  If not, see <http://www.gnu.org/licenses/>.

perl v5.26.2                   Perl::Critic::Policy::Compatibility::PerlMinimumVersionAndWhy(3pm)