Perl::Critic::PolicPerl::Critic::Policy::Variables::ProhibitPunctuationVars(3)NAMEPerl::Critic::Policy::Variables::ProhibitPunctuationVars - Write
"$EVAL_ERROR" instead of "$@".
AFFILIATION
This Policy is part of the core Perl::Critic distribution.
DESCRIPTION
Perl's vocabulary of punctuation variables such as $!, $., and $^ are
perhaps the leading cause of its reputation as inscrutable line noise.
The simple alternative is to use the English module to give them clear
names.
$| = undef; #not ok
use English qw(-no_match_vars);
local $OUTPUT_AUTOFLUSH = undef; #ok
CONFIGURATION
The scratch variables $_ and @_ are very common and are pretty well
understood, so they are exempt from this policy. The same goes for the
less-frequently-used default filehandle "_" used by stat(). All the
regexp capture variables ($1, $2, ...) are exempt too. $] is exempt
because there is no English equivalent and Module::CoreList is based
upon it.
You can add more exceptions to your configuration. In your
perlcriticrc file, add a block like this:
[Variables::ProhibitPunctuationVars]
allow = $@ $!
The "allow" property should be a whitespace-delimited list of
punctuation variables.
Other configuration options control the parsing of interpolated
strings in the search for forbidden variables. They have no effect on
detecting punctuation variables outside of interpolated strings.
[Variables::ProhibitPunctuationVars]
string_mode = thorough
The option "string_mode" controls whether and how interpolated
strings are searched for punctuation variables. Setting "string_mode =
thorough", the default, checks for special cases that may look like
punctuation variables but aren't, for example $#foo, an array index
count; $$bar, a scalar dereference; or $::baz, a global symbol.
Setting "string_mode = disable" causes all interpolated strings to be
ignored entirely.
Setting "string_mode = simple" uses a simple regular expression to
find matches. In this mode, the magic variables $$, "$'", $# and $:
are ignored within interpolated strings due to the high risk of
false positives. Simple mode is retained from an earlier draft of
the interpolated- strings code. Its use is only recommended as a
workaround if bugs appear in thorough mode.
The "string_mode" option will go away when the parsing of
interpolated strings is implemented in PPI. See "CAVEATS" below.
BUGS
Punctuation variables that confuse PPI's document parsing may not be
detected correctly or at all, and may prevent detection of
subsequent ones. In particular, $" is known to cause difficulties in
interpolated strings.
CAVEATS
ProhibitPunctuationVars relies exclusively on PPI to find
punctuation variables in code, but does all the parsing itself for
interpolated strings. When, at some point, this functionality is
transferred to PPI, ProhibitPunctuationVars will cease doing the
interpolating and the "string_mode" option will go away.
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 v5.14.1Perl::Critic::Policy::Variables::ProhibitPunctuationVars(3)
