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Perl::Critic::Policy::Community::DiscouragedModules - Various modules discouraged from use


Various modules are discouraged by some subsets of the community, for various reasons which may include: buggy behavior, cruft, performance problems, maintainer issues, or simply better modern replacements. This is a high severity complement to Perl::Critic::Policy::Community::PreferredAlternatives.



AnyEvent's author refuses to use public bugtracking and actively breaks interoperability. POE, IO::Async, and Mojo::IOLoop are widely used and interoperable async event loops.


Any::Moose is deprecated. Use Moo instead.


Class::DBI is an ancient database ORM abstraction layer which is buggy and abandoned. See DBIx::Class for a more modern DBI-based ORM, or Mad::Mapper for a Mojolicious-style ORM.

CGI is an ancient module for communicating via the CGI protocol, with tons of bad practices and cruft. Use a modern framework such as those based on Plack (Web::Simple, Dancer2, Catalyst) or Mojolicious, they can still be served via CGI if you choose. Use CGI::Tiny if you are limited to the CGI protocol.


Coro abuses Perl internals in an unsupported way. Consider Future and Future::AsyncAwait in combination with event loops for similar semantics.

Error is overly magical and discouraged by its maintainers. Try Throwable for exception classes in Moo/Moose, or Exception::Class otherwise. Try::Tiny or Syntax::Keyword::Try are recommended for the try/catch syntax.


FindBin is often used to retrieve the absolute path to the directory containing the initially executed script, a mechanism which is not always logically clear. Additionally, it has serious bugs on old Perls and can't be updated from CPAN to fix them. The Path::This module provides similar variables and constants based on the absolute path to the current source file. The lib::relative module resolves passed relative paths to the current source file for the common case of adding local module include directories. Each of these documents examples of achieving the same behavior with core modules.


File::Slurp gets file encodings all wrong, line endings on win32 are messed up, and it was written before layers were properly added. Use File::Slurper, "slurp" in Path::Tiny, "slurp" in Data::Munge, or "slurp" in Mojo::File.


HTML::Template is an old and buggy module, try Template::Toolkit, Mojo::Template, or Text::Xslate instead, or HTML::Template::Pro if you must use the same syntax.


IO::Socket::INET6 is an old attempt at an IPv6 compatible version of IO::Socket::INET, but has numerous issues and is discouraged by the maintainer in favor of IO::Socket::IP, which transparently creates IPv4 and IPv6 sockets.


IP::World was built from two free publicly available databases. However, over the years one of them was discontinued, and the other is no longer being updated. Therefore the module's accuracy is ever-decreasing. Try GeoIP2 as an alternative. That code is also deprecated, but at least its database is still updated.


JSON::Any is deprecated. Use JSON::MaybeXS instead.


JSON::XS's author refuses to use public bugtracking and actively breaks interoperability. Cpanel::JSON::XS is a fork with several bugfixes and a more collaborative maintainer. See also JSON::MaybeXS.


Net::IRC is an ancient module implementing the IRC protocol. Use a modern event-loop-based module instead. Choices are POE::Component::IRC (used for Bot::BasicBot), Net::Async::IRC, and Mojo::IRC.

Switch is a buggy and outdated source filter which can cause any number of strange errors, in addition to the problems with smart-matching shared by its replacement, "The 'switch' feature" in feature (given/when). Try Switch::Plain or Syntax::Keyword::Match instead.


XML::Simple tries to coerce complex XML documents into perl data structures. This leads to overcomplicated structures and unexpected behavior. Use a proper DOM parser instead like XML::LibXML, XML::TreeBuilder, XML::Twig, or Mojo::DOM.


This policy is part of Perl::Critic::Community.


Occasionally you may find yourself needing to use one of these discouraged modules, and do not want the warnings. You can do so by putting something like the following in a .perlcriticrc file like this:

    allowed_modules = FindBin Any::Moose

The same option is offered for Perl::Critic::Policy::Community::PreferredAlternatives.


Dan Book,


Copyright 2015, Dan Book.

This library is free software; you may redistribute it and/or modify it under the terms of the Artistic License version 2.0.