---
name: "Perl::Critic::Policy::Subroutines::ProhibitBuiltinHomonyms"
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::Subroutines::ProhibitBuiltinHomonyms"
---

# Perl::Critic::Policy::Subroutines::ProhibitBuiltinHomonyms(3pm)

Don't declare your own "open" function.

## NAME

Perl::Critic::Policy::Subroutines::ProhibitBuiltinHomonyms - Don't declare your own "open" function.

## AFFILIATION

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

## DESCRIPTION

Common sense dictates that you shouldn't declare subroutines with the same name as one of Perl's built-in functions or keywords.  See perlfunc for a list of built-in functions; see perlsyn for keywords.

```
  sub open {}    #not ok
  sub exit {}    #not ok
  sub print {}   #not ok
  sub foreach {} #not ok
  sub if {}      #not ok
  #You get the idea...
```

Exceptions are made for `"BEGIN"`, `"END"`, `"INIT"` and `"CHECK"` blocks, as well as `"AUTOLOAD"`, `"DESTROY"`, and `"import"` subroutines.

## CONFIGURATION

You can configure additional builtin homonyms to accept by specifying them in a space-delimited list to the `"allow"` option:

```
    [Subroutines::ProhibitBuiltinHomonyms]
    allow = default index
```

These are added to the default list of exemptions from this policy. So the above allows `"sub default {}"` and `"sub index {}"`.

## CAVEATS

It is reasonable to declare an **object** method with the same name as a Perl built-in function, since they are easily distinguished from each other.  However, at this time, Perl::Critic cannot tell whether a subroutine is static or an object method.

## AUTHOR

Jeffrey Ryan Thalhammer \<jeff@imaginative-software.com\>

## COPYRIGHT

Copyright (c) 2005-2022 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.