/ 
perl-critic-policy-prohibitunusedimports-1.000
/ Perl::Critic::Policy::ProhibitUnusedImports

NAME

Perl::Critic::Policy::ProhibitUnusedImports - An import nobody uses is a dependency nobody knew they had.

VERSION

version 1.000

Perl::Critic::Policy::ProhibitUnusedImports

A use nobody uses costs load time, drags a prerequisite along behind it, and tells the next reader something about this file that isn't true:

use FindBin();          # ...and $FindBin::Bin appears nowhere below
use POSIX qw{floor};    # ...and floor() is never called

They accumulate. A sub gets rewritten, the import that fed it stays, and a year later somebody is keeping a module in Makefile.PL for the sake of a line that does nothing.

This resolves each imported name and looks for a use of it in the rest of the document:

use Module LIST

Each name in the list has to appear -- as a call, a symbol, or after an &.

use Module;

Whatever @EXPORT says, if the module can be loaded and says anything. With an empty @EXPORT this is the same case as the next one.

use Module ();

Nothing is imported, so the module's own name has to appear: Module::thing, Module->method, or $Module::VAR.

PROHIBITED

use FindBin();
print "hello\n";                    # nothing named FindBin below

use List::Util qw{first any};
my @x = grep { $_ } @y;             # neither one called

ALLOWED

use FindBin();
print $FindBin::Bin;

use List::Util qw{any};
return any { $_ } @list;

Pragmas and other modules whose entire job is a side effect are exempt; see allow below.

CONFIGURATION

allow

Space separated list of modules that are never reported, because importing them is the point. Adds to the built-in list rather than replacing it, so you name only what is yours:

[ProhibitUnusedImports]
allow = My::Company::Bootstrap

The built-in list is the pragmas plus the usual side-effect modules:

strict warnings utf8 feature lib autodie parent base constant
vars subs overload open integer bytes locale sigtrap version experimental
Filter::Simple Carp::Always FindBin::libs

CAVEATS

Modules exporting into a namespace this file only reaches at runtime -- a symbolic call, a string eval, an AUTOLOAD -- read as unused, because the source does not say otherwise. Add them to allow.

Loading the module to read its @EXPORT means running its top-level code, so this policy is unsafe by Perl::Critic's definition and needs --allow-unsafe. When the module will not load, its default exports are unknown and the use Module; case is skipped rather than guessed at.

METHODS

supported_parameters

allow, the modules that are never reported, added to the built-in list.

initialize_if_enabled

Folds the built-in exemptions back into whatever allow was configured with, so a user's list adds to the defaults instead of replacing them.

default_severity

SEVERITY_LOW

default_themes

maintenance, performance

applies_to

PPI::Statement::Include

is_safe

False. Reading @EXPORT means loading the module, which runs its top-level code, so this policy needs --allow-unsafe.

violates

Standard Perl::Critic::Policy interface. Returns a violation for a use whose imports -- or whose own name, when it imports nothing -- appear nowhere else in the document.

BUGS

Please report any bugs or feature requests on the bugtracker website https://github.com/teodesian/perl-critic-policy-prohibitunusedimports/issues

When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature.

AUTHORS

Current Maintainers:

  • George S. Baugh <teodesian@gmail.com>

COPYRIGHT AND LICENSE

Copyright (c) 2026 Troglodyne LLC

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.