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 1The above creates a file named
rm *|. When perl opens it with<>it actually executes the shell programrm *. 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
BUGS
This is only a very preliminary version.
AUTHOR
Malcolm Beattie, mbeattie@sable.ox.ac.uk.
ACKNOWLEDGEMENTS
Sebastien Aperghis-Tramoni - bug fixes