NAME

       Perl::Critic::Policy::Subroutines::ProhibitUnusedPrivateSubroutines - Prevent unused
       private subroutines.

AFFILIATION

       This Policy is part of the core Perl::Critic distribution.

DESCRIPTION

       By convention Perl authors (like authors in many other languages) indicate private methods
       and variables by inserting a leading underscore before the identifier.  This policy
       catches such subroutines which are not used in the file which declares them.

       This module defines a 'use' of a subroutine as a subroutine or method call to it (other
       than from inside the subroutine itself), a reference to it (i.e.  "my $foo = \&_foo"), a
       "goto" to it outside the subroutine itself (i.e.  "goto &_foo"), or the use of the
       subroutine's name as an even-numbered argument to "use overload".

CONFIGURATION

       You can define what a private subroutine name looks like by specifying a regular
       expression for the "private_name_regex" option in your .perlcriticrc:

           [Subroutines::ProhibitUnusedPrivateSubroutines]
           private_name_regex = _(?!_)\w+

       The above example is a way of saying that subroutines that start with a double underscore
       are not considered to be private.  (Perl::Critic, in its implementation, uses leading
       double underscores to indicate a distribution-private subroutine -- one that is allowed to
       be invoked by other Perl::Critic modules, but not by anything outside of Perl::Critic.)

       You can configure additional subroutines to accept by specifying them in a space-delimited
       list to the "allow" option:

           [Subroutines::ProhibitUnusedPrivateSubroutines]
           allow = _bar _baz

       These are added to the default list of exemptions from this policy. So the above allows
       "sub _bar {}" and "sub _baz {}", even if they are not referred to in the module that
       defines them.

       You can allow a whole class or subroutine names by defining a regular expression that
       matches allowed names.

           [Subroutines::ProhibitUnusedPrivateSubroutines]
           allow_name_regex = _build_\w+

       You can configure this policy not to check private subroutines declared in a file that
       uses one or more particular named modules.  This allows you to, for example, exclude
       unused private subroutine checking in classes that are roles.

           [Subroutines::ProhibitUnusedPrivateSubroutines]
           skip_when_using = Moose::Role Moo::Role Role::Tiny

HISTORY

       This policy is derived from Perl::Critic::Policy::Subroutines::ProtectPrivateSubs, which
       looks at the other side of the problem.

BUGS

       Does not forbid "sub Foo::_foo{}" because it does not know (and can not assume) what is in
       the "Foo" package.

       Does not respect the scope caused by multiple packages in the same file.  For example a
       file:

           package Foo;
           sub _is_private { print "A private sub!"; }

           package Bar;
           _is_private();

       Will not trigger a violation even though "Foo::_is_private" is not called.  Similarly,
       "skip_when_using" currently works on a file level, not on a package scope level.

SEE ALSO

       Perl::Critic::Policy::Subroutines::ProtectPrivateSubs.

AUTHOR

       Chris Dolan <cdolan@cpan.org>

COPYRIGHT

       Copyright (c) 2009-2021 Thomas R. Wyant, III.

       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 v5.36.0             Perl::Critic::Policy::Subroutines::ProhibitUnusedPrivateSubroutines(3pm)