10-17-2012
I favor the use of the single quote for fastest and most certain processing, as it expands nothing. You can switch to double wuotes where you want expansion or a literal single quote, and then go back to single quoting. Since there is no expansion, there is less processing. For file wild card expansion, or globbing, you need to be outside quotes. I rather like a pipe: "echo '....' | command" over a here file: "command <<EOD
....
EOD" as I can predict and view expansions easily.
The eval I save for odd situations, like constructing a variable name from a varible and then fetching it. It is a shell built-in, so probably faster than `sh -c 'echo $x'"$m"`
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LEARN ABOUT DEBIAN
perl::critic::policy::valuesandexpressions::prohibitinterpolatio
Perl::Critic::Policy::ValuesAndExpressions::ProhibitInteUseraContrPerl::Critic::Policy::ValuesAndExpressions::ProhibitInterpolationOfLiterals(3pm)
NAME
Perl::Critic::Policy::ValuesAndExpressions::ProhibitInterpolationOfLiterals - Always use single quotes for literal strings.
AFFILIATION
This Policy is part of the core Perl::Critic distribution.
DESCRIPTION
Don't use double-quotes or "qq//" if your string doesn't require interpolation. This saves the interpreter a bit of work and it lets the
reader know that you really did intend the string to be literal.
print "foobar"; #not ok
print 'foobar'; #ok
print qq/foobar/; #not ok
print q/foobar/; #ok
print "$foobar"; #ok
print "foobar
"; #ok
print qq/$foobar/; #ok
print qq/foobar
/; #ok
print qq{$foobar}; #preferred
print qq{foobar
}; #preferred
Use of double-quotes might be reasonable if the string contains single quote (') characters:
print "it's me"; # ok, if configuration flag set
CONFIGURATION
The types of quoting styles to exempt from this policy can be configured via the "allow" option. This must be a whitespace-delimited
combination of some or all of the following styles: "qq{}", "qq()", "qq[]", and "qq//".
This is useful because some folks have configured their editor to apply special syntax highlighting within certain styles of quotes. For
example, you can tweak "vim" to use SQL highlighting for everything that appears within "qq{}" or "qq[]" quotes. But if those strings are
literal, Perl::Critic will complain. To prevent this, put the following in your .perlcriticrc file:
[ValuesAndExpressions::ProhibitInterpolationOfLiterals]
allow = qq{} qq[]
The flag "allow_if_string_contains_single_quote" permits double-quoted strings if the string contains a single quote (') character. It
defaults to off; to turn it on put the following in your .perlcriticrc file:
[ValuesAndExpressions::ProhibitInterpolationOfLiterals]
allow_if_string_contains_single_quote = 1
SEE ALSO
Perl::Critic::Policy::ValuesAndExpressions::RequireInterpolationOfMetachars
AUTHOR
Jeffrey Ryan Thalhammer <jeff@imaginative-software.com>
COPYRIGHT
Copyright (c) 2005-2011 Imaginative Software Systems. All rights reserved.
This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. The full text of this license
can be found in the LICENSE file included with this module.
perl v5.14.2 Perl::Critic::Policy::ValuesAndExpressions::ProhibitInterpolationOfLiterals(3pm)