ELLIOTJS / Perl-Critic-1.101_003 / lib / Perl / Critic / Policy / Variables / ProhibitUnusedVariables.pm 

            

              
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
—
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161

              
##############################################################################
#      $URL: http://perlcritic.tigris.org/svn/perlcritic/branches/Perl-Critic-PPI-1.204/lib/Perl/Critic/Policy/Variables/ProhibitUnusedVariables.pm $
#     $Date: 2009-07-22 10:19:39 -0700 (Wed, 22 Jul 2009) $
#   $Author: clonezone $
# $Revision: 3435 $
##############################################################################
package Perl::Critic::Policy::Variables::ProhibitUnusedVariables;
use 5.006001;
use strict;
use warnings;
use Readonly;
use List::MoreUtils qw< any >;
use PPI::Token::Symbol;
use Perl::Critic::Utils qw< :characters :severities >;
use base 'Perl::Critic::Policy';
our $VERSION = '1.101_003';
#-----------------------------------------------------------------------------
Readonly::Scalar my $EXPL =>
    q<Unused variables clutter code and make it harder to read>;
#-----------------------------------------------------------------------------
sub supported_parameters { return ()                     }
sub default_severity     { return $SEVERITY_MEDIUM       }
sub default_themes       { return qw< core maintenance > }
sub applies_to           { return qw< PPI::Document >    }
#-----------------------------------------------------------------------------
sub violates {
    my ( $self, $elem, $document ) = @_;
    my %symbol_usage = _get_symbol_usage($document);
    return if not %symbol_usage;
    my $declarations = $document->find('PPI::Statement::Variable');
    return if not $declarations;
    my @violations;
    DECLARATION:
    foreach my $declaration ( @{$declarations} ) {
        next DECLARATION if 'my' ne $declaration->type();
        my @children = $declaration->schildren();
        next DECLARATION if any { $_ eq q<=> } @children;
        VARIABLE:
        foreach my $variable ( $declaration->variables() ) {
            my $count = $symbol_usage{ $variable };
            next VARIABLE if not $count; # BUG!
            next VARIABLE if $count > 1;
            push
                @violations,
                $self->violation(
                    qq<"$variable" is declared but not used.>,
                    $EXPL,
                    $declaration,
                );
        }
    }
    return @violations;
}
sub _get_symbol_usage {
    my ($document) = @_;
    my $symbols = $document->find('PPI::Token::Symbol');
    return if not $symbols;
    my %symbol_usage;
    foreach my $symbol ( @{$symbols} ) {
        $symbol_usage{ $symbol->symbol() }++;
    }
    return %symbol_usage;
}
#-----------------------------------------------------------------------------
1;
__END__
#-----------------------------------------------------------------------------
=pod
=head1 NAME
Perl::Critic::Policy::Variables::ProhibitUnusedVariables - Don't ask for storage you don't need.
=head1 AFFILIATION
This Policy is part of the core L<Perl::Critic|Perl::Critic>
distribution.
=head1 DESCRIPTION
Unused variables clutter code and require the reader to do mental
bookkeeping to figure out if the variable is actually used or not.
At present, this Policy is very limited in order to ensure that there
aren't any false positives.  Hopefully, this will become more
sophisticated soon.
Right now, this only looks for simply declared, uninitialized lexical
variables.
    my $x;          # not ok, assuming no other appearances.
    my @y = ();     # ok, not handled yet.
    our $z;         # ok, global.
    local $w;       # ok, global.
This module is very dumb: it does no scoping detection, i.e. if the
same variable name is used in two different locations, even if they
aren't the same variable, this Policy won't complain.
Have to start somewhere.
=head1 CONFIGURATION
This Policy is not configurable except for the standard options.
=head1 AUTHOR
Elliot Shank C<< <perl@galumph.com> >>
=head1 COPYRIGHT
Copyright (c) 2008-2009 Elliot Shank.  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.
=cut
# Local Variables:
#   mode: cperl
#   cperl-indent-level: 4
#   fill-column: 78
#   indent-tabs-mode: nil
#   c-indentation-style: bsd
# End:
# ex: set ts=8 sts=4 sw=4 tw=78 ft=perl expandtab shiftround :