Perl has had experimental features ever since I started using it at about version 5.6. These were things that were considered useful, but about which there was doubt -- about their final form, whether a satisfactory implementation existed, or whatever.

Until Perl 5.18, experimental features were simply documented as experimental. At that point, an experimental warning category was added, with sub-categories experimental::lexical_subs, experimental::lexical_topic, ="prettyprint…

The deprecated warning is a grab-bag. Basically, anything that is deprecated causes this warning to be generated, and the list changes from release to release.

The only reason I can think of ever to turn this off is around a deprecated construction while you are actively working to eliminate it. Silencing it and then forgetting about it will bite you, eventually.

For the curious (and to run my word count, since otherwise this would be a really short blog entry), the current list of deprecations…

Warning categories have proliferated since the warnings pragma was first introduced in Perl 5.6: from 50 in Perl 5.6.2 to 79 in Perl 5.35.5 (the latest as of this writing). But warnings have been removed as well as added. This post documents these -- mostly for historical interest on my part.

chmod

This warning flagged a chmod statement wi…

Term::ReadLine is a core module (since Perl 5.002) that provides an extremely limited text interface of the prompt-and-type variety. Its main virtue is that you can add a back end which gives it things like command history, editing, and completion.

The back ends live in the Term::ReadLine::* name space, and you can control which one you get by defining the PERL_RL environment variable as documented at ="https://metacpan.org/pod…