Don't assign an anonymous arrayref to an array
This policy is a fork of Perl::Critic::Policy::ValuesAndExpressions::ProhibitArrayAssignAref. It differs from the original by not having a dependency on List::MoreUtils. It is unfortunately still licensed as GPL3.
It asks you not to assign an anonymous arrayref to an array
@array = [ 1, 2, 3 ]; # bad
The idea is that it's rather unclear whether an arrayref is intended, or might have meant to be a list like
@array = ( 1, 2, 3 );
This policy is under the "bugs" theme (see "POLICY THEMES" in Perl::Critic)
for the chance [] is a mistake, and since even if it's correct it will
likely make anyone reading it wonder.
A single arrayref can still be assigned to an array, but with parens to make it clear,
@array = ( [1,2,3] ); # ok
Dereferences or array and hash slices (see "Slices" in perldata) are recognised as an array target and treated similarly,
@$ref = [1,2,3]; # bad assign to deref
@{$ref} = [1,2,3]; # bad assign to deref
@x[1,2,3] = ['a','b','c']; # bad assign to array slice
@x{'a','b'} = [1,2]; # bad assign to hash slice
This policy is not a blanket requirement for () parens on array
assignments. It's normal and unambiguous to have a function call or grep
etc without parens.
@array = foo(); # ok
@array = grep {/\.txt$/} @array; # ok
The only likely problem from lack of parens in such cases is that the ,
comma operator has lower precedence than = (see perlop), so something
like
@array = 1,2,3; # oops, not a list
means
@array = (1);
2;
3;
Normally the remaining literals in void context provoke a warning from Perl itself.
An intentional single element assignment is quite common as a statement, for instance
@ISA = 'My::Parent::Class'; # ok
And for reference the range operator precedence is high enough,
@array = 1..10; # ok
But of course parens are needed if concatenating some disjoint ranges with the comma operator,
@array = (1..5, 10..15); # parens needed
The qw form gives a list too
@array = qw(a b c); # ok
Copyright 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2019, 2021 Kevin Ryde
Perl-Critic-Policy-Plicease-ProhibitArrayAssignAref 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-Policy-Plicease-ProhibitArrayAssignAref 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-Policy-Plicease-ProhibitArrayAssignAref. If not, see <http://www.gnu.org/licenses>.
Original author: Kevin Ryde
Current maintainer: Graham Ollis plicease@cpan.org
This software is Copyright (c) 2011-2021 by Kevin Ryde.
This is free software, licensed under:
The GNU General Public License, Version 3, June 2007