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 only available in a newer Perl than you thought to support.

An explicit use 5.xxx in your code can be tedious, but makes it clear what you need (or think you need) and it gets a good error message if run on an older Perl. The config below lets you limit how far back you might go. Or if you don't care at all about this sort of thing you can always disable the policy completely from you ~/.perlcriticrc file in the usual way,

    [-Compatibility::PerlMinimumVersionAndWhy]

MinimumVersion Mangling

Some mangling is applied to what Perl::MinimumVersion normally reports (as of its version 1.20).

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

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

MinimumVersion Extras

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

• qr//m requires Perl 5.10, as the "m" modifier doesn't propagate correctly on a qr until then.

• exists &subr, exists $array[0] or delete $array[0] require Perl 5.6.

• Foo::Bar:: double-colon package name requires Perl 5.005.

• use 5.005 and similar Perl version check new in Perl 5.004. For earlier Perl it's BEGIN { require 5.003 } or similar instead.

• __PACKAGE__ special literal new in Perl 5.004.

• foreach my $foo lexical loop variable new in Perl 5.004.

• pack and unpack format strings are checked for various new conversions in Perl 5.004 through 5.10.0. Currently this only works on literal strings or here-documents without interpolations, and . operator concats of those.

CONFIGURATION

above_version (version string, default none)

Set a minimum version of Perl you always use, so reports are only about things both higher than this and higher than the document declares. The string is anything version.pm understands. For example,

    [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 silently ignored.

SEE ALSO

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

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