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
|
package Perl::Critic::Policy::Freenode::Wantarray;
use strict;
use warnings;
use Perl::Critic::Utils qw(:severities :classification :ppi);
use parent 'Perl::Critic::Policy';
our $VERSION = '0.033';
use constant DESC => 'wantarray() called';
use constant EXPL => 'Context-sensitive functions lead to unexpected errors or vulnerabilities. Functions should explicitly return either a list or a scalar value.';
sub supported_parameters { () }
sub default_severity { $SEVERITY_LOW }
sub default_themes { 'freenode' }
sub applies_to { 'PPI::Token::Word' }
sub violates {
my ($self, $elem) = @_;
return () unless (($elem eq 'wantarray' or $elem->literal eq 'CORE::wantarray') and is_function_call $elem);
return $self->violation(DESC, EXPL, $elem);
}
1;
=head1 NAME
Perl::Critic::Policy::Freenode::Wantarray - Don't write context-sensitive
functions using wantarray
=head1 DESCRIPTION
Context-sensitive functions, while one way to write functions that DWIM (Do
What I Mean), tend to instead lead to unexpected behavior when the function is
accidentally used in a different context, especially if the function's behavior
changes significantly based on context. This also can lead to vulnerabilities
when a function is intended to be used as a scalar, but is used in a list, such
as a hash constructor or function parameter list. Instead, functions should be
explicitly documented to return either a scalar value or a list, so there is no
potential for confusion or vulnerability.
return wantarray ? ('a','b','c') : 3; # not ok
return CORE::wantarray ? ('a', 'b', 'c') : 3; # not ok
return ('a','b','c'); # ok
return 3; # ok
sub get_stuff {
return wantarray ? @things : \@things;
}
my $stuff = Stuff->new(stuff => get_stuff()); # oops! function will return a list!
=head1 AFFILIATION
This policy is part of L<Perl::Critic::Freenode>.
=head1 CONFIGURATION
This policy is not configurable except for the standard options.
=head1 AUTHOR
Dan Book, C<dbook@cpan.org>
=head1 COPYRIGHT AND LICENSE
Copyright 2015, Dan Book.
This library is free software; you may redistribute it and/or modify it under
the terms of the Artistic License version 2.0.
=head1 SEE ALSO
L<Perl::Critic>
|
