Perl::Critic::Policy::ValuesAndExpressions::ProhibitEmptyCommas - disallow empty consecutive commas

This policy is part of the Perl::Critic::Pulp|Perl::Critic::Pulp addon. It prohibits empty comma operators , or => meaning either consecutive commas or a comma at the start of a list or expression.

    print 'foo',,'bar';      # bad
    @a = (,1,2);             # bad
    foo (x, => 123);         # bad
    a =>=> 456;              # bad
    for (; $i++<10; $i++,,)  # bad
    func (,)                 # bad

Extra commas like this are harmless and simply collapse out when the program runs (see List value constructors in perldata), so this policy is only under the "cosmetic" theme (see POLICY THEMES in Perl::Critic). Usually this sort of thing is just a stray, or leftover from cut and paste, or perhaps some over-enthusiastic column layout. Occasionally it can be something more dubious,

    # did you mean 1..6 range operator?
    @a = (1,,6);        # bad

    # this is two args, did you want three?
    foo (1, , 2);       # bad

    # this is three args, probably you forgot a value
    bar (abc => ,       # bad
         def => 20);

A comma at the end of a list or call is allowed. That's quite usual and can be a good thing when cutting and pasting lines (see RequireTrailingCommas to mandate them!).

    @b = ("foo",
          "bar",  # ok
         );

If you use multiple commas in some systematic way for code layout you can always disable ProhibitEmptyCommas from your .perlcriticrc file in the usual way (see CONFIGURATION in Perl::Critic),

    [-ValuesAndExpressions::ProhibitEmptyCommas]

Perl::Critic::Pulp, Perl::Critic, Perl::Critic::Policy::CodeLayout::RequireTrailingCommas, Perl::Critic::Policy::ValuesAndExpressions::ProhibitCommaSeparatedStatements, Perl::Critic::Policy::Tics::ProhibitManyArrows

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

Copyright 2008, 2009, 2010, 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/>.