Perl::Critic::Policy::Documentation::ProhibitDuplicateHeadings - don't duplicate =head names
This policy is part of the Perl::Critic::Pulp add-on. It asks you not to duplicate heading names in =head POD commands.
=head1 SOMETHING # bad, duplicate
Duplication is usually a mistake, perhaps too much cut-and-paste, or a leftover from a template, or perhaps text in two places which ought to be together. On that basis this policy is medium severity and under the "bugs" theme (see "POLICY THEMES" in Perl::Critic).
The policy default is to demand that a given heading is unique to its ancestors, siblings, and to the immediately adjacent heading irrespective of level. This is designed to be how human readers perceive the scope of headings and subheadings, plus adjacency in case a mixture of heading levels would let a duplicate otherwise go undetected. For example
=head3 Top # bad, duplicates its ancestor head1
=head2 Down # bad, duplicates sibling head2
=head1 Blah # bad, duplicates adjacent
A subheading can be repeated if it's under a different higher heading. For example the following two "Details" are cousins, so allowed.
=head2 Details # ok
Option uniqueness=all (see "CONFIGURATION" below) applies a stricter rule so that all =head names must be unique throughout the document, irrespective of levels and structure.
=head3 Foo # bad
One use for this is to ensure all headings can be reached by an L<> link. An L<> only has the heading name, no level or path, so if there's any duplication among the names then only the first of each duplicate will be reachable. (The POD browsers usually go to the first among duplicates.)
This rule is often too strict. It can be good to have similar subheadings like "Details" as shown above, with no need to make such sub-parts reachable by a link.
If you don't care at all about this you can disable ProhibitDuplicateHeadings from your .perlcriticrc in the usual way (see "CONFIGURATION" in Perl::Critic),
The uniqueness to be enforced on each heading. The value is a comma-separated list of
default currently "ancestor,sibling,adjacent"
ancestor don't duplicate parent, grandparent, etc
sibling same level and parent
adjacent immediately preceding, irrespective of level
all all headings
The default is "default" and the intention is to have default mean a sensible set of restrictions, though precisely what it might be could change.
For example in your .perlcriticrc file
Copyright 2013, 2014, 2015, 2016, 2017, 2019, 2021 Kevin Ryde
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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.
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To install Perl::Critic::Pulp, copy and paste the appropriate command in to your terminal.
perl -MCPAN -e shell
For more information on module installation, please visit the detailed CPAN module installation guide.