/ 
Perl-Critic-Policy-Subroutines-ProhibitSingleUseLexicalSubs-0.001
/ Perl::Critic::Policy::Subroutines::ProhibitSingleUseLexicalSubs

NAME

Perl::Critic::Policy::Subroutines::ProhibitSingleUseLexicalSubs - Inline a lexical sub that is used in only one place.

VERSION

version 0.001

Perl::Critic::Policy::Subroutines::ProhibitSingleUseLexicalSubs

A lexical sub that one place uses is that place, moved somewhere else. The reader goes to find it, reads it, and comes back. Put the body where it is used, and the reader reads it once, in order:

my sub total { return sum map { $_->{price} } @_ }    # reported
say total(@items);

say sum map { $_->{price} } @items;

my $by_name = sub { $a->{name} cmp $b->{name} };       # reported
my @sorted  = sort $by_name @people;

my @sorted = sort { $a->{name} cmp $b->{name} } @people;

A name still earns its place when two or more places use it.

PROHIBITED

my sub helper { ... }            helper(@args);
state sub helper { ... }         helper(@args);
my sub helper { ... }            my $ref = \&helper;
my $helper = sub { ... };        $helper->(@args);
my $helper = sub { ... };        $self->$helper(@args);
my $helper = sub { ... };        some_function($helper);

ALLOWED

my sub helper { ... }            helper(1); helper(2);
my sub walk { ... walk(@kids) }  walk($root);     # it calls itself
my sub helper { ... }                             # unused: see CAVEATS
sub helper { ... }               helper(@args);   # a package sub
our $helper = sub { ... };       $helper->();     # a package variable

CAVEATS

A sub that nothing uses is not reported. Subroutines::ProhibitUnusedPrivateSubroutines and the policies about unused variables report that, and it wants deleting rather than inlining.

The count is of the code after the declaration, in the same block, as PPI parses it. A use inside a string, such as "@{[ helper() ]}", is not counted, so a sub used there and in one other place is reported.

If the block declares the same name again, the policy cannot tell which declaration a use refers to, and it reports nothing for that name. That said, this can only happen without strictures enabled so you have bigger problems.

A sub passed as a callback, such as find({ wanted => $wanted }, $dir), should be inlined as an anonymous sub.

METHODS

supported_parameters

default_severity

default_themes

applies_to

violates

BUGS

Please report any bugs or feature requests on the bugtracker website https://github.com/teodesian/perl-critic-policy-prohibitsingleuselexicalsubs/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 <george@troglodyne.net>

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.