B::Lint
B::Lint
B::Lint - Perl lint
perl -MO=Lint[,OPTIONS] foo.pl
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:
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.
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);
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) { ... }
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.
$_ is used either explicitly anywhere or
as the implicit argument of a print statement.
$_ and @_).
foo() and not indirect invocations such as &$subref()
or $obj->meth(). Note that some programs or modules delay
definition of subs until runtime by means of the AUTOLOAD
mechanism.
$`, $& or $'
is used. Any occurrence of any of these variables in your
program can slow your whole program down. See perlre for
details.
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} ) {
...
}
}
This is only a very preliminary version.
Malcolm Beattie, mbeattie@sable.ox.ac.uk.
Sebastien Aperghis-Tramoni - bug fixes