Perl::Critic::Policy::UPerl::Critic::Policy::Variables::ProhibitPackageVars(3)NAMEPerl::Critic::Policy::Variables::ProhibitPackageVars - Eliminate
globals declared with "our" or "use vars".
AFFILIATION
This Policy is part of the core Perl::Critic distribution.
DESCRIPTION
Conway suggests avoiding package variables completely, because they
expose your internals to other packages. Never use a package variable
when a lexical variable will suffice. If your package needs to keep
some dynamic state, consider using an object or closures to keep the
state private.
This policy assumes that you're using "strict vars" so that naked
variable declarations are not package variables by default. Thus, it
complains you declare a variable with "our" or "use vars", or if you
make reference to variable with a fully-qualified package name.
$Some::Package::foo = 1; # not ok
our $foo = 1; # not ok
use vars '$foo'; # not ok
$foo = 1; # not allowed by 'strict'
local $foo = 1; # bad taste, but technically ok.
use vars '$FOO'; # ok, because it's ALL CAPS
my $foo = 1; # ok
In practice though, its not really practical to prohibit all package
variables. Common variables like $VERSION and @EXPORT need to be
global, as do any variables that you want to Export. To work around
this, the Policy overlooks any variables that are in ALL_CAPS. This
forces you to put all your exported variables in ALL_CAPS too, which
seems to be the usual practice anyway.
CONFIGURATION
There is room for exceptions. Some modules, like the core File::Find
module, use package variables as their only interface, and others like
Data::Dumper use package variables as their most common interface.
These module can be specified from your .perlcriticrc file, and the
policy will ignore them.
[Variables::ProhibitPackageVars]
packages = Data::Dumper File::Find FindBin Log::Log4perl
This is the default setting. Using "packages =" will override these
defaults.
You can also add packages to the defaults like so:
[Variables::ProhibitPackageVars]
add_packages = My::Package
You can add package "main" to the list of packages, but that will only
OK variables explicitly in the "main" package.
SEE ALSO
Perl::Critic::Policy::Variables::ProhibitPunctuationVars
Perl::Critic::Policy::Variables::ProhibitLocalVars
AUTHOR
Jeffrey Ryan Thalhammer <jeff@imaginative-software.com>
COPYRIGHT
Copyright (c) 2005-2011 Imaginative Software Systems. All rights
reserved.
This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself. The full text of this license can
be found in the LICENSE file included with this module.
perl v5.14.1Perl::Critic::Policy::Variables::ProhibitPackageVars(3)
