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B::Lint(3pm)           Perl Programmers Reference Guide           B::Lint(3pm)




NAME

       B::Lint - Perl lint


SYNOPSIS

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


DESCRIPTION

       The B::Lint module is equivalent to an extended version of the -w
       option of perl. It is named after the program lint which carries out a
       similar process for C programs.


OPTIONS AND LINT CHECKS

       Option words are separated by commas (not whitespace) and follow the
       usual conventions of compiler backend options. Following any options
       (indicated by a leading -) come lint check arguments. Each such
       argument (apart from the special all and none options) is a word
       representing one possible lint check (turning on that check) or is no-
       foo (turning off that check). Before processing the check arguments, a
       standard list of checks is turned on. Later options override earlier
       ones. Available options are:

       magic-diamond
               Produces a warning whenever the magic "<>" readline is used.
               Internally it uses perl's two-argument open which itself treats
               filenames with special characters specially. This could allow
               interestingly named files to have unexpected effects when
               reading.

                 % touch 'rm *|'
                 % perl -pe 1

               The above creates a file named "rm *|". When perl opens it with
               "<>" it actually executes the shell program "rm *". This makes
               "<>" dangerous to use carelessly.

       context Produces a warning whenever an array is used in an implicit
               scalar context. For example, both of the lines

                   $foo = length(@bar);
                   $foo = @bar;

               will elicit a warning. Using an explicit scalar() silences the
               warning. For example,

                   $foo = scalar(@bar);

       implicit-read and implicit-write
               These options produce a warning whenever an operation
               implicitly reads or (respectively) writes to one of Perl's
               special variables.  For example, implicit-read will warn about
               these:

                   /foo/;

               and implicit-write will warn about these:

                   s/foo/bar/;

               Both implicit-read and implicit-write warn about this:

                   for (@a) { ... }

       bare-subs
               This option warns whenever a bareword is implicitly quoted, but
               is also the name of a subroutine in the current package.
               Typical mistakes that it will trap are:

                   use constant foo => 'bar';
                   @a = ( foo => 1 );
                   $b{foo} = 2;

               Neither of these will do what a naive user would expect.

       dollar-underscore
               This option warns whenever $_ is used either explicitly
               anywhere or as the implicit argument of a print statement.

       private-names
               This option warns on each use of any variable, subroutine or
               method name that lives in a non-current package but begins with
               an underscore ("_"). Warnings aren't issued for the special
               case of the single character name "_" by itself (e.g. $_ and
               @_).

       undefined-subs
               This option warns whenever an undefined subroutine is invoked.
               This option will only catch explicitly invoked subroutines such
               as "foo()" and not indirect invocations such as "&$subref()" or
               "$obj->meth()". Note that some programs or modules delay
               definition of subs until runtime by means of the AUTOLOAD
               mechanism.

       regexp-variables
               This option warns whenever one of the regexp variables "$`", $&
               or "$'" is used. Any occurrence of any of these variables in
               your program can slow your whole program down. See perlre for
               details.

       all     Turn all warnings on.

       none    Turn all warnings off.


NON LINT-CHECK OPTIONS

       -u Package
               Normally, Lint only checks the main code of the program
               together with all subs defined in package main. The -u option
               lets you include other package names whose subs are then
               checked by Lint.


EXTENDING LINT

       Lint can be extended by with plugins. Lint uses Module::Pluggable to
       find available plugins. Plugins are expected but not required to inform
       Lint of which checks they are adding.

       The "B::Lint->register_plugin( MyPlugin => \@new_checks )" method adds
       the list of @new_checks to the list of valid checks. If your module
       wasn't loaded by Module::Pluggable then your class name is added to the
       list of plugins.

       You must create a "match( \%checks )" method in your plugin class or
       one of its parents. It will be called on every op as a regular method
       call with a hash ref of checks as its parameter.

       The class methods "B::Lint->file" and "B::Lint->line" contain the
       current filename and line number.

         package Sample;
         use B::Lint;
         B::Lint->register_plugin( Sample => [ 'good_taste' ] );

         sub match {
             my ( $op, $checks_href ) = shift @_;
             if ( $checks_href->{good_taste} ) {
                 ...
             }
         }


TODO

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


BUGS

       This is only a very preliminary version.


AUTHOR

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



perl v5.10.0                      2007-12-18                      B::Lint(3pm)

Mac OS X 10.6 - Generated Thu Sep 17 20:10:43 CDT 2009
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