---
name: "Perl::Critic::Policy::Variables::ProhibitPunctuationVars"
section: "3pm"
platform: "linux"
package: "perl-perl-critic"
version: "1.156-3"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/Perl::Critic::Policy::Variables::ProhibitPunctuationVars"
---

# Perl::Critic::Policy::Variables::ProhibitPunctuationVars(3pm)

Write "$EVAL\_ERROR" instead of "$@".

## NAME

Perl::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) 2005-2023 Imaginative Software Systems

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.