Perl::Critic::Policy::Modules::ProhibitModuleShebang

NAME

Perl::Critic::Policy::Modules::ProhibitModuleShebang - don’t put a #! line at the start of a module file

DESCRIPTION

This policy is part of the "Perl::Critic::Pulp" add-on. It asks you not to use a "#!" interpreter line in a .pm module file.

#!/usr/bin/perl -w <-- bad
package Foo;
...

This "#!" does nothing but might make a reader think it’s supposed to be a program instead of a module. Often the "#!" is a leftover cut and paste from a script into a module, perhaps when grabbing a copyright notice or similar intro.

Of course a module works the same with or without, so this policy is low severity and under the "cosmetic" theme (see "POLICY THEMES" in Perl::Critic).

Only the first line of a file is a prospective "#!" interpreter. A "#!" anywhere later is allowed, for example in code which generates other code,

sub foo {
print <<HERE;
#!/usr/bin/make <-- ok
# Makefile generated by Foo.pm - DO NOT EDIT
...

This policy applies only to .pm files. Anything else, such as ".pl" or ".t" scripts can have "#!", or not, in the usual way. Modules are identified by the .pm filename because it’s hard to distinguish a module from a script just by the content.

Disabling
If you don’t care about this you can always disable "ProhibitModuleShebang" from your .perlcriticrc in the usual way (see "CONFIGURATION" in Perl::Critic),

[-Modules::ProhibitModuleShebang]

CONFIGURATION

"allow_bin_false" (boolean, default true)

If true then allow "#!/bin/false" in module files.

#! /bin/false <-- ok

Such a "#!" prevents executing the code if accidentally run as a script. Whether you want this is a personal preference. It indicates a module is not a script and so accords with "ProhibitModuleShebang", but in general it’s probably unnecessary.

SEE ALSO

Perl::Critic::Pulp, Perl::Critic

HOME PAGE

<http://user42.tuxfamily.org/perl-critic-pulp/index.html>

COPYRIGHT

Copyright 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2019, 2021 Kevin Ryde

Perl-Critic-Pulp is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3, or (at your option) any later version.

Perl-Critic-Pulp is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with Perl-Critic-Pulp. If not, see <http://www.gnu.org/licenses>.