Perl::Critic::Policy::ValuesAndExpressions::ProhibitQuotesAsQuotelikeOperatorDelimiters3pm

Affiliation

This Policy is part of the core Perl::Critic distribution.

Overview

With the obvious exception of using single-quotes to prevent interpolation, using quotes with the quote-like operators kind of defeats the purpose of them and produces obfuscated code, causing problems for future maintainers and their editors/IDEs.

    $x = q"q";                #not ok
    $x = q'q';                #not ok
    $x = q`q`;                #not ok
    $x = qq"q";               #not ok
    $x = qr"r";               #not ok
    $x = qw"w";               #not ok
    $x = qx`date`;            #not ok
    $x =~ m"m";               #not ok
    $x =~ s"s"x";             #not ok
    $x =~ tr"t"r";            #not ok
    $x =~ y"x"y";             #not ok
    $x =~ m'$x';              #ok
    $x =~ s'$x'y';            #ok
    $x = qr'$x'm;             #ok
    $x = qx'finger foo@bar';  #ok

Configuration

This policy has three options: "single_quote_allowed_operators", "double_quote_allowed_operators", and "back_quote_allowed_operators", which control which operators are allowed to use each of "'", """, "`" as delimiters, respectively.

The values allowed for these options are a whitespace delimited selection of the "m", "q", "qq", "qr", "qw", "qx", "s", "tr", and "y" operators.

By default, double quotes and back quotes (backticks) are not allowed as delimiters for any operators and single quotes are allowed as delimiters for the "m", "qr", "qx", and "s" operators. These defaults are equivalent to having the following in your .perlcriticrc:

    [ValuesAndExpressions::ProhibitQuotesAsQuotelikeOperatorDelimiters]
    single_quote_allowed_operators = m s qr qx
    double_quote_allowed_operators =
    back_quote_allowed_operators =

Suggested by

Michael Schwern