/ 
Perl-Critic-Pulp-54
River stage two • 5 direct dependents • 18 total dependents
/ Perl::Critic::Policy::Compatibility::PerlMinimumVersionAndWhy

NAME

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

DESCRIPTION

This policy is part of the Perl::Critic::Pulp addon. 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 Perl::MinimumVersion 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 tedious, but makes it clear what's needed (or supposed to be needed) and it gives a good error message if run on an older Perl.

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 1.20).

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

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

    The same rationale doesn't apply to pragma modules like use warnings since they're normally an interface to a feature new in the Perl version it comes with and can't be back-ported.

MinimumVersion Extras

The following extra checks are added to what Perl::MinimumVersion normally reports.

5.10

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

5.8

  • 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.

5.6

  • new exists &subr, exists $array[0] or delete $array[0] support.

  • new 0b110011 binary number literals.

5.005

  • new Foo::Bar:: double-colon package name

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

5.004

  • new use 5.000 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

5.004 through 5.10.0

pack and unpack format strings are checked for various new conversions. Currently this only works on formats given as literal strings or here-documents, without interpolations, or . operator concats of those.

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 the document declares. The value is anything the version.pm module understands.

[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 bit of 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 its lexically-scoped fine grain warnings control is new in that version. If targeting earlier versions then it's often enough to drop use warnings, make sure your code runs cleanly under perl -w, and leave it to applications to use -w (or set $^W) or not, as they might desire.

warnings::compat offers a use warnings for earlier Perl, but it's not lexical, instead setting $^W globally. Doing that from a module is probably not a good idea, but in a script it could be an alternative to #!/usr/bin/perl -w (as per perlrun).

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 2008, 2009, 2010, 2011 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/>.