B::Lint(3perl)

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:

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.

BUGS
This is only a very preliminary version.

This module doesn't work correctly on thread-enabled perls.

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