Perl::Critic::Policy::Variables::ProhibitEvilVariables(3User Contributed Perl DocumentatiPerl::Critic::Policy::Variables::ProhibitEvilVariables(3)

NAME

       Perl::Critic::Policy::Variables::ProhibitEvilVariables - Ban variables that aren't blessed by your shop.

AFFILIATION

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

DESCRIPTION

       Use this policy if you wish to prohibit the use of specific variables. These may be global variables warned against in "perlvar", or just
       variables whose names you do not like.

CONFIGURATION

       The set of prohibited variables is configurable via the "variables" and "variables_file" options.

       The value of "variables" should be a string of space-delimited, fully qualified variable names and/or regular expressions.  An example of
       prohibiting two specific variables in a .perlcriticrc file:

	   [Variables::ProhibitEvilVariables]
	   variables = $[ $^S $SIG{__DIE__}

       If you prohibit an array or hash (e.g. @INC), use of elements of the array or hash will be prohibited as well. If you specify a subscripted
       variable (e.g.  $SIG{__DIE__}), only the literal subscript specified will be detected. The above <.perlcritic> file, for example, will
       cause "perlcritic (1)" to detect "$SIG{__DIE__} = &foo", but not

	   my $foo = '__DIE__';
	   $SIG{$foo} = &foo;

       Regular expressions are identified by values beginning and ending with slashes.	Any variable with a name that matches "m/pattern/sm" will
       be forbidden.  For example:

	   [Variables::ProhibitEvilVariables]
	   variables = /acme/

       would cause all variables that match "m/acme/" to be forbidden.	If you want a case-blind check, you can use (?i: ... ).  For example

	   [Variables::ProhibitEvilVariables]
	   variables = /(?i:acme)/

       forbids variables that match "m/acme/smi".

       In addition, you can override the default message ("Prohibited variable "variable" used") with your own, in order to give suggestions for
       alternative action.  To do so, put your message in curly braces after the variable name or regular expression.  Like this:

	   [Variables::ProhibitEvilVariables]
	   variables = $[ {Found use of $[. Program to base index 0 instead}

       If your message contains curly braces, you can enclose it in parentheses, angle brackets, or square brackets instead.

       Similarly, the "variables_file" option gives the name of a file containing specifications for prohibited variables.  Only one variable
       specification is allowed per line and comments start with an octothorp and run to end of line; no curly braces are necessary for delimiting
       messages:

	   $[	   # Prohibit the "$[" variable and use the default message.

	   # Prohibit the "$^S" variable and give a replacement message.
	   $^S	   Having to think about $^S in exception handlers is just wrong

	   # Use a regular expression.
	   /acme/  No coyotes allowed.

       By default, there are no prohibited variables, although I can think of a few that should be.  See "perldoc perlvar" for a few suggestions.

RESTRICTIONS

       Variables of the form "${^foo}" are not recognized by PPI as of version 1.206. When PPI recognizes these, this policy will Just Work for
       them too.

       Only direct references to prohibited variables and literal subscripts will be recognized. For example, if you prohibit $[, the first line
       in

	my $foo = $[;
	$$foo = 1;

       will be flagged as a violation, but not the second, even though the second, in fact, assigns to $[. Similarly, if you prohibit
       $SIG{__DIE__}, this policy will not recognize

	my $foo = '__DIE__';
	$SIG{$foo} = sub {warn 'I cannot die!'};

       as an assignment to $SIG{__DIE__}.

NOTES

       This policy leans heavily on Perl::Critic::Policy::Modules::ProhibitEvilModules by Jeffrey Ryan Thalhammer.

AUTHOR

       Thomas R. Wyant, III wyant at cpan dot org

COPYRIGHT

       Copyright (c) 2009-2011 Thomas R. Wyant, III

       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 v5.16.3							    2014-06-09		 Perl::Critic::Policy::Variables::ProhibitEvilVariables(3)