Removing Duplicate PATH Entries, Part II: the Rise of Perl

Mitch Frazier — Tue, 04 Dec 2018 12:30:00 +0000

With apologies to Arnold and the Terminator franchise for the title, let's look one more time at removing duplicates from the PATH variable. This take on doing it was prompted by a comment from a reader named Shaun on the previous post that asked "if you're willing to use a non-bash solution (AWK) to solve the problem, why not use Perl?" Shaun was kind enough to provide a Perl version of the code, which was good, since I'd have been hard-pressed to come up with one. It's a short piece of code, shorter than the AWK version, so it seemed like it ought to be fairly easy to pick it apart. In the end, I'm not sure I'd call it easy, but it was interesting, and I thought other non-Perl programmers might find it interesting too.

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Moose

Henry Van Styn — Mon, 23 Jan 2012 15:00:00 +0000

by Henry Van Styn

Perl has been around for more than 20 years. During that time, it has received its share of both praise and criticism, and lots of misconceptions surround it. Much of this stems from long-outdated notions of what Perl used to be, but have nothing to do with what Perl actually is today.

Perl hasn't been standing still. It's been growing continuously and evolving, and that growth has accelerated dramatically in the past few years. Moose is one of the technologies at the heart of this "Perl Renaissance", which also includes other exciting projects that have emerged, such as Catalyst and DBIx::Class.

Moose is essentially a language extension for Perl 5 that provides a modern, elegant, fully featured object system. I say "language extension", but Moose is written in pure Perl, and as you'll see, its syntax is still normal Perl. You don't need to patch Perl itself to use Moose; under the hood, it's just Perl 5.

Because Moose is still just Perl 5, it's fully compatible with all of those wonderful modules on CPAN, regardless of whether they are written in Moose (and most aren't, as CPAN has been around for so long, and Moose is relatively new).

For me, this is still the single biggest reason to choose Perl. Whatever you are trying to accomplish, chances are, there already is a refined module for it on CPAN. This usually means dramatic cuts in total development time, because someone else already has written a lot of your program for you.

And now, with all the modern object-oriented features Moose brings to Perl, you get to have your cake and eat it too.

In this article, I provide an introduction to object-oriented programming in Moose and cover some of Moose's core features with useful examples. To get the most out of this article, you already should be familiar with object-oriented programming concepts, such as classes, objects, methods, attributes, construction and inheritance.

You also need to know Perl—at least the fundamentals. If you don't know Perl, learning it is not very hard to do. At the end of the day, it's just syntax. The good news is you don't need to master Perl by any stretch to start using Moose.

Perl does have its quirks, and Moose doesn't make them all totally go away (and you wouldn't want them all to go away, because a lot of them are really useful). The most important concepts to understand are how Perl references work (the "perlreftut" tutorial is a great place to start—see Resources), and also the basics of working with Scalars, Arrays and Hashes. Also, learn what the fat comma is (=>) if you aren't already familiar with it. Moose makes heavy use of it as an idiom. It's actually not that scary; it's interchangeable with the normal comma (,).

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