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:
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. |
−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.
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} ) {
...
}
}
while(<
FH >) stomps $_
strict oo
unchecked system calls
more tests, validate against older perls
This is only a very preliminary version.
Malcolm Beattie, mbeattie@sable.ox.ac.uk.
Sebastien Aperghis-Tramoni − bug fixes
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