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