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Perl::Critic::Policy::Documentation::ProhibitUnbalancedParens(3pm) User Contributed Perl Documentation Perl::Critic::Policy::Documentation::ProhibitUnbalancedParens(3pm)


Perl::Critic::Policy::Documentation::ProhibitUnbalancedParens - don't leave an open bracket or paren


This policy is part of the "Perl::Critic::Pulp" add-on. It reports unbalanced or mismatched parentheses, brackets and braces in POD text paragraphs,

    Blah blah (and something.    # bad
    Blah blah ( [ ).             # bad
    Blah blah brace }.           # bad

This is only cosmetic and normally only a minor irritant to readability so this policy is low severity and under the "cosmetic" theme (see "POLICY THEMES" in Perl::Critic).

Text and command paragraphs are checked, but verbatim paragraphs can have anything. There are some exceptions to paren balancing. The intention is to be forgiving of common or reasonable constructs. Currently this means,

  • Anything in "C<>" code markup is ignored

        In code C<anything [ is allowed>.  # ok

    Perhaps this will change, though there'd have to be extra exceptions in "C<>", such as various backslashing.

    Sometimes a prematurely ending "C<>" may look like an unbalanced paren, for example

        Call C<foo(key=>value)> ...    # bad

    This is bad because the "C<>" ends at the "=>", leaving "value)" unbalanced plain text. This is an easy mistake to make. (The author's "perl-pod-gt.el" can show warning face on this in Emacs.)

  • Quoted "(" is taken to be describing the char and is not an open or close.

        Any of "(" or '[' or "[{]".   # ok

    This only applies to quoted parens alone (one or more), not larger quoted text.

  • Item parens

        a) the first thing, or b) the second thing   # ok
        1) one, 2) two     # ok

    Exactly how much is recognised as an "a)" etc is not quite settled. In the current code a "1.5)" is recognised at the start of a paragraph, but in the middle only "1)" style.

  • Smiley faces are an "optional" close,

        (Some thing :-).                # ok
        Bare smiley :).                 # ok
        (Or smile :-) and also close.)  # ok
  • Sad smiley faces are not an opening paren,

        :( :-(.     # ok
  • Perl variables $( and $[ are not opening parens,

        Default is group $( blah blah.  # ok

    ${ brace is still an open and expected to have a matching close, because it's likely to be a deref or delimiter,

        Deref with ${foo()} etc etc.

    Variables or expressions like this will often be in "C<>" markup and skipped for that reason instead, as described above.

  • $) and $] are optional closes, since they might be Perl variables to skip, or might be "$" at the end of a parens,

       blah blah (which in TeX is $1\cdot2$).

    Perhaps the conditions for these will be restricted a bit, though again "C<>" markup around sample code like this will be usual.

  • "L<display|link>" links are processed as the "display" text part. The link target (POD document name and section) can have anything.

"=begin :foo" ... "=end :foo" sections with a format name ":foo" starting with a ":" are POD markup and are processed accordingly. Other "=begin" sections are skipped.

Unrecognised Forms

A mathematical half-open range like the following is not recognised.

    [1,2)             # bad, currently

Perhaps just numbers like this would be unambiguous, but if it's an expression then it's hard to distinguish a parens typo from some mathematics. The suggestion for now is an "=for" per below to flag it as an exception. Another way would be to write 1 <= X < 2, which might be clearer to mathematically unsophisticated readers.

Parens spanning multiple paragraphs are not recognised,

    (This is some     # bad
    thing.)           # bad

Hopefully this is uncommon, and probably better style not to be parenthetical about something so big that it runs to multiple paragraphs or has a verbatim block in the middle etc.


If an unbalanced paren is intended you can add an "=for" to tell "ProhibitUnbalancedParens" to allow it.

    =for ProhibitUnbalancedParens allow next
    Something ( deliberately unclosed.

Or with a count of paragraphs to ignore,

    =for ProhibitUnbalancedParens allow next 2
    First deliberate [ unclosed.
    Second (.

The usual no critic

    ## no critic (ProhibitUnbalancedParens)

works too as a whole-file disable, but the annotation must be before any "__END__" token, and if the POD is after the "__END__" then "Perl::Critic" 1.112 up is required. Individual "=for" has the advantage of being with an exception.

As always if you don't care about this at all you can disable "ProhibitUnbalancedParens" completely from your .perlcriticrc in the usual way (see "CONFIGURATION" in Perl::Critic),



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




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 <>.

2021-02-28 perl v5.32.1