1B::Lint(3) User Contributed Perl Documentation B::Lint(3)
2
6 B::Lint - Perl lint
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9 perl -MO=Lint[,OPTIONS] foo.pl
10
12 The B::Lint module is equivalent to an extended version of the -w
13 option of perl. It is named after the program lint which carries out a
14 similar process for C programs.
15
17 Option words are separated by commas (not whitespace) and follow the
18 usual conventions of compiler backend options. Following any options
19 (indicated by a leading -) come lint check arguments. Each such
20 argument (apart from the special all and none options) is a word
21 representing one possible lint check (turning on that check) or is no-
22 foo (turning off that check). Before processing the check arguments, a
23 standard list of checks is turned on. Later options override earlier
24 ones. Available options are:
25 magic-diamond
27 Produces a warning whenever the magic "<>" readline is used.
28 Internally it uses perl's two-argument open which itself treats
29 filenames with special characters specially. This could allow
30 interestingly named files to have unexpected effects when
31 reading.
32 % touch 'rm *|'
34 % perl -pe 1
35 The above creates a file named "rm *|". When perl opens it with
37 "<>" it actually executes the shell program "rm *". This makes
38 "<>" dangerous to use carelessly.
39 context Produces a warning whenever an array is used in an implicit
41 scalar context. For example, both of the lines
42 $foo = length(@bar);
44 $foo = @bar;
45 will elicit a warning. Using an explicit scalar() silences the
47 warning. For example,
48 $foo = scalar(@bar);
50 implicit-read and implicit-write
52 These options produce a warning whenever an operation
53 implicitly reads or (respectively) writes to one of Perl's
54 special variables. For example, implicit-read will warn about
55 these:
56 /foo/;
58 and implicit-write will warn about these:
60 s/foo/bar/;
62 Both implicit-read and implicit-write warn about this:
64 for (@a) { ... }
66 bare-subs
68 This option warns whenever a bareword is implicitly quoted, but
69 is also the name of a subroutine in the current package.
70 Typical mistakes that it will trap are:
71 use constant foo => 'bar';
73 @a = ( foo => 1 );
74 $b{foo} = 2;
75 Neither of these will do what a naive user would expect.
77 Notice: Perl 5.22.0 does not report "foo" in $b{foo} as BARE
79 token anymore. Therefore B::Lint test is not reliable here. See
80 CPAN RT#101115
81 <https://rt.cpan.org/Public/Bug/Display.html?id=101115>.
82 dollar-underscore
84 This option warns whenever $_ is used either explicitly
85 anywhere or as the implicit argument of a print statement.
86 private-names
88 This option warns on each use of any variable, subroutine or
89 method name that lives in a non-current package but begins with
90 an underscore ("_"). Warnings aren't issued for the special
91 case of the single character name "_" by itself (e.g. $_ and
92 @_).
93 undefined-subs
95 This option warns whenever an undefined subroutine is invoked.
96 This option will only catch explicitly invoked subroutines such
97 as "foo()" and not indirect invocations such as "&$subref()" or
98 "$obj->meth()". Note that some programs or modules delay
99 definition of subs until runtime by means of the AUTOLOAD
100 mechanism.
101 regexp-variables
103 This option warns whenever one of the regexp variables "$`", $&
104 or "$'" is used. Any occurrence of any of these variables in
105 your program can slow your whole program down. See perlre for
106 details.
107 all Turn all warnings on.
109 none Turn all warnings off.
111
113 -u Package
114 Normally, Lint only checks the main code of the program
115 together with all subs defined in package main. The -u option
116 lets you include other package names whose subs are then
117 checked by Lint.
118
120 Lint can be extended by with plugins. Lint uses Module::Pluggable to
121 find available plugins. Plugins are expected but not required to inform
122 Lint of which checks they are adding.
123 The "B::Lint->register_plugin( MyPlugin => \@new_checks )" method adds
125 the list of @new_checks to the list of valid checks. If your module
126 wasn't loaded by Module::Pluggable then your class name is added to the
127 list of plugins.
128 You must create a "match( \%checks )" method in your plugin class or
130 one of its parents. It will be called on every op as a regular method
131 call with a hash ref of checks as its parameter.
132 The class methods "B::Lint->file" and "B::Lint->line" contain the
134 current filename and line number.
135 package Sample;
137 use B::Lint;
138 B::Lint->register_plugin( Sample => [ 'good_taste' ] );
139 sub match {
141 my ( $op, $checks_href ) = shift @_;
142 if ( $checks_href->{good_taste} ) {
143 ...
144 }
145 }
146
148 while(<FH>) stomps $_
149 strict oo
150 unchecked system calls
151 more tests, validate against older perls
152
154 This is only a very preliminary version.
155
157 Malcolm Beattie, mbeattie@sable.ox.ac.uk.
158
160 Sebastien Aperghis-Tramoni - bug fixes
161perl v5.34.0 2022-01-20 B::Lint(3)