1B::Lint(3)            User Contributed Perl Documentation           B::Lint(3)
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NAME

6       B::Lint - Perl lint
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SYNOPSIS

9       perl -MO=Lint[,OPTIONS] foo.pl
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DESCRIPTION

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.
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OPTIONS AND LINT CHECKS

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:
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26       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
33                 % touch 'rm *|'
34                 % perl -pe 1
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36               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.
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40       context Produces a warning whenever an array is used in an implicit
41               scalar context. For example, both of the lines
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43                   $foo = length(@bar);
44                   $foo = @bar;
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46               will elicit a warning. Using an explicit scalar() silences the
47               warning. For example,
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49                   $foo = scalar(@bar);
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51       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:
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57                   /foo/;
58
59               and implicit-write will warn about these:
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61                   s/foo/bar/;
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63               Both implicit-read and implicit-write warn about this:
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65                   for (@a) { ... }
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67       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:
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72                   use constant foo => 'bar';
73                   @a = ( foo => 1 );
74                   $b{foo} = 2;
75
76               Neither of these will do what a naive user would expect.
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78               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>.
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83       dollar-underscore
84               This option warns whenever $_ is used either explicitly
85               anywhere or as the implicit argument of a print statement.
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87       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. $_ and
92               @_).
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94       undefined-subs
95               This option warns whenever an undefined subroutine is invoked.
96               This option will only catch explicitly invoked subroutines such
97               as "foo()" and not indirect invocations such as "&$subref()" or
98               "$obj->meth()". Note that some programs or modules delay
99               definition of subs until runtime by means of the AUTOLOAD
100               mechanism.
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102       regexp-variables
103               This option warns whenever one of the regexp variables "$`", $&
104               or "$'" is used. Any occurrence of any of these variables in
105               your program can slow your whole program down. See perlre for
106               details.
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108       all     Turn all warnings on.
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110       none    Turn all warnings off.
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NON LINT-CHECK OPTIONS

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.
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EXTENDING LINT

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.
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124       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.
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129       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.
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133       The class methods "B::Lint->file" and "B::Lint->line" contain the
134       current filename and line number.
135
136         package Sample;
137         use B::Lint;
138         B::Lint->register_plugin( Sample => [ 'good_taste' ] );
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140         sub match {
141             my ( $op, $checks_href ) = shift @_;
142             if ( $checks_href->{good_taste} ) {
143                 ...
144             }
145         }
146

TODO

148       while(<FH>) stomps $_
149       strict oo
150       unchecked system calls
151       more tests, validate against older perls
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BUGS

154       This is only a very preliminary version.
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AUTHOR

157       Malcolm Beattie, mbeattie@sable.ox.ac.uk.
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ACKNOWLEDGEMENTS

160       Sebastien Aperghis-Tramoni - bug fixes
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164perl v5.32.1                      2021-01-26                        B::Lint(3)
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