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Perl::Critic::Policy::ValuesAndExpressions::ProhibitArrayAssignAref(3) | User Contributed Perl Documentation | Perl::Critic::Policy::ValuesAndExpressions::ProhibitArrayAssignAref(3) |
NAME¶
Perl::Critic::Policy::ValuesAndExpressions::ProhibitArrayAssignAref - don't assign an anonymous arrayref to an array
DESCRIPTION¶
This policy is part of the "Perl::Critic::Pulp" add-on. 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
List Assignment Parens¶
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
SEE ALSO¶
Perl::Critic, Perl::Critic::Pulp
HOME PAGE¶
COPYRIGHT¶
Copyright 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>.
2021-03-01 | perl v5.40.0 |