/ 
Perl-Critic-Pulp-63
River stage two • 5 direct dependents • 13 total dependents
/ Perl::Critic::Policy::ValuesAndExpressions::ProhibitArrayAssignAref

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 addon. It asks you not to assign an anonymous arrayref to an array

@array = [ 1, 2, 3 ];       # bad

The idea is that it's a rather unclear whether an arrayref is intended, or might have meant a list like

@array = ( 1, 2, 3 );

For the chance the [] is a mistake and since it will make anyone reading it wonder, this policy is under the "bugs" theme (see "POLICY THEMES" in Perl::Critic).

It's perfectly good to assign a single arrayref to an array, but put parens to make it clear,

@array = ( [1,2,3] );       # ok

Derefs and array and hash slices (see "Slices" in perldata) are recognised and treated likewise,

@$ref = [1,2,3];            # bad to deref
@{$ref} = [1,2,3];          # bad to deref
@x[1,2,3] = ['a','b','c'];  # bad to array slice
@x{'a','b'} = [1,2];        # bad to hash slice

List Assignment Parens

There's no blanket requirement for () parens on an array assignment here since it's normal and unambiguous to have a function call or grep etc.

@array = foo();
@array = grep {/\.txt$/} @array;

The only likely problem from lack of parens is that the , comma operator has lower precedence than = (see perlop), so something like

@array = 1,2,3;   # not a list

means

@array = (1);
2;
3;

Normally the remaining literals in void context provoke a compile time warning.

An intentional single element assignment is quite common though, as a statement, for instance

@ISA = 'My::Parent::Class';

For reference the range operator precedence is high enough,

@array=1..10;              # fine

though 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);        # fine

SEE ALSO

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

HOME PAGE

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

COPYRIGHT

Copyright 2011 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>.