Perl::Critic::Policy::Subroutines::ProtectPrivateSubs - Prevent access to private subs in other packages.

Perl-Critic documentation Contained in the Perl-Critic distribution.

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NAME

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Perl::Critic::Policy::Subroutines::ProtectPrivateSubs - Prevent access to private subs in other packages.

AFFILIATION

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

DESCRIPTION

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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 attempts to access private variables from outside the package itself.

The subroutines in the POSIX package which begin with an underscore (e.g. POSIX::_POSIX_ARG_MAX) are not flagged as errors by this policy.

CONFIGURATION

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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::ProtectPrivateSubs]
    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::ProtectPrivateSubs]
    allow = FOO::_bar FOO::_baz

These are added to the default list of exemptions from this policy. Allowing a subroutine also allows the corresponding method call. So FOO::_bar in the above example allows both FOO::_bar() and FOO->_bar().

HISTORY

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This policy is inspired by a similar test in B::Lint (B::Lint).

BUGS

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Doesn't forbid $pkg->_foo() because it can't tell the difference between that and $self->_foo().

SEE ALSO

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Perl::Critic::Policy::Variables::ProtectPrivateVars

AUTHOR

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Chris Dolan <cdolan@cpan.org>

COPYRIGHT

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Copyright (c) 2006-2011 Chris Dolan.

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-Critic documentation Contained in the Perl-Critic distribution. 
##############################################################################
#      $URL: http://perlcritic.tigris.org/svn/perlcritic/trunk/distributions/Perl-Critic/lib/Perl/Critic/Policy/Subroutines/ProtectPrivateSubs.pm $
#     $Date: 2011-05-15 16:34:46 -0500 (Sun, 15 May 2011) $
#   $Author: clonezone $
# $Revision: 4078 $
##############################################################################

package Perl::Critic::Policy::Subroutines::ProtectPrivateSubs;

use 5.006001;

use strict;
use warnings;

use English qw< $EVAL_ERROR -no_match_vars >;
use Readonly;

use Perl::Critic::Utils qw<
    :severities $EMPTY is_function_call is_method_call
>;
use base 'Perl::Critic::Policy';

our $VERSION = '1.116';

#-----------------------------------------------------------------------------

Readonly::Scalar my $DESC => q<Private subroutine/method used>;
Readonly::Scalar my $EXPL => q<Use published APIs>;

#-----------------------------------------------------------------------------

sub supported_parameters {
    return (
        {
            name            => 'private_name_regex',
            description     => 'Pattern that determines what a private subroutine is.',
            default_string  => '\b_\w+\b',  ## no critic (RequireInterpolationOfMetachars)
            behavior        => 'string',
            parser          => \& _parse_private_name_regex,
        },
        {
            name            => 'allow',
            description     =>
                q<Subroutines matching the private name regex to allow under this policy.>,
            default_string  => $EMPTY,
            behavior        => 'string list',
            list_always_present_values => [ qw<
                POSIX::_PC_CHOWN_RESTRICTED
                POSIX::_PC_LINK_MAX
                POSIX::_PC_MAX_CANON
                POSIX::_PC_MAX_INPUT
                POSIX::_PC_NAME_MAX
                POSIX::_PC_NO_TRUNC
                POSIX::_PC_PATH_MAX
                POSIX::_PC_PIPE_BUF
                POSIX::_PC_VDISABLE
                POSIX::_POSIX_ARG_MAX
                POSIX::_POSIX_CHILD_MAX
                POSIX::_POSIX_CHOWN_RESTRICTED
                POSIX::_POSIX_JOB_CONTROL
                POSIX::_POSIX_LINK_MAX
                POSIX::_POSIX_MAX_CANON
                POSIX::_POSIX_MAX_INPUT
                POSIX::_POSIX_NAME_MAX
                POSIX::_POSIX_NGROUPS_MAX
                POSIX::_POSIX_NO_TRUNC
                POSIX::_POSIX_OPEN_MAX
                POSIX::_POSIX_PATH_MAX
                POSIX::_POSIX_PIPE_BUF
                POSIX::_POSIX_SAVED_IDS
                POSIX::_POSIX_SSIZE_MAX
                POSIX::_POSIX_STREAM_MAX
                POSIX::_POSIX_TZNAME_MAX
                POSIX::_POSIX_VDISABLE
                POSIX::_POSIX_VERSION
                POSIX::_SC_ARG_MAX
                POSIX::_SC_CHILD_MAX
                POSIX::_SC_CLK_TCK
                POSIX::_SC_JOB_CONTROL
                POSIX::_SC_NGROUPS_MAX
                POSIX::_SC_OPEN_MAX
                POSIX::_SC_PAGESIZE
                POSIX::_SC_SAVED_IDS
                POSIX::_SC_STREAM_MAX
                POSIX::_SC_TZNAME_MAX
                POSIX::_SC_VERSION
                POSIX::_exit
            > ],
        },
    );
}

sub default_severity     { return $SEVERITY_MEDIUM       }
sub default_themes       { return qw( core maintenance ) }
sub applies_to           { return 'PPI::Token::Word'     }

#-----------------------------------------------------------------------------

sub _parse_private_name_regex {
    my ($self, $parameter, $config_string) = @_;

    defined $config_string
        or $config_string = $parameter->get_default_string();

    my $regex;
    eval { $regex = qr/$config_string/; 1 } ## no critic (RegularExpressions)
        or $self->throw_parameter_value_exception(
            'private_name_regex',
            $config_string,
            undef,
            "is not a valid regular expression: $EVAL_ERROR",
        );

    $self->__set_parameter_value($parameter, $regex);

    return;
}

#-----------------------------------------------------------------------------

sub violates {
    my ( $self, $elem, undef ) = @_;

    if ( my $prior = $elem->sprevious_sibling() ) {
        my $prior_name = $prior->content();
        return if $prior_name eq 'package';
        return if $prior_name eq 'require';
        return if $prior_name eq 'use';
    }

    if (
            $self->_is_other_pkg_private_function($elem)
        or  $self->_is_other_pkg_private_method($elem)
    ) {
        return $self->violation( $DESC, $EXPL, $elem );
    }

    return;  # ok!
}

sub _is_other_pkg_private_function {
    my ( $self, $elem ) = @_;

    return if ! is_function_call($elem) && ! is_method_call($elem);

    my $private_name_regex = $self->{_private_name_regex};
    my $content = $elem->content();
    return
            $content =~ m< \w+::$private_name_regex \z >xms
        &&  $content !~ m< \A SUPER::$private_name_regex \z >xms
        &&  ! $self->{_allow}{$content};
}

sub _is_other_pkg_private_method {
    my ( $self, $elem ) = @_;

    my $private_name_regex = $self->{_private_name_regex};
    my $content = $elem->content();

    # look for structures like "Some::Package->_foo()"
    return if $content !~ m< \A $private_name_regex \z >xms;
    my $operator = $elem->sprevious_sibling() or return;
    return if $operator->content() ne q[->];

    my $package = $operator->sprevious_sibling() or return;
    return if not $package->isa('PPI::Token::Word');

    # sometimes the previous sib is a keyword, as in:
    # shift->_private_method();  This is typically used as
    # shorthand for "my $self=shift; $self->_private_method()"
    return if $package eq 'shift' or $package eq '__PACKAGE__';

    # Maybe the user wanted to exempt this explicitly.
    return if $self->{_allow}{"${package}::$content"};

    return 1;
}

1;

__END__

#-----------------------------------------------------------------------------


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