Manual Reference Pages  - B::Lint (3pm)


B::Lint - Perl lint



perl -MO=Lint[,OPTIONS]


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.


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:


and implicit-write will warn about these:


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.


-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.


This is only a very preliminary version.

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


Malcolm Beattie,

perl v5.8.8 B::Lint (3pm) 2001-09-21
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