TweetFollow Us on Twitter

Apr 00 Online

Volume Number: 16 (2000)
Issue Number: 4
Column Tag: MacTech Online

Of Perl and Salsa

by Jeff Clites (online@mactech.com)

If computer languages were edible, Perl would be cilantro: some people love it and some people hate it, but no one who's tried it walks away indifferent. Many Macintosh programmer may barely have heard of it, but it's a staple of the Unix world. It's also known varyingly as the Swiss army knife of the internet and the duct tape of the internet, but either way it's a piece of hardware that should be in every programmer's tool box, whether you use it frequently or infrequently. So what's so special about Perl, and why should you care? I'm glad you asked.

A First Look

First, here's the clinical description: Perl is a cross-platform interpreted language, with implementations available for almost every conceivable platform (including the Macintosh and Windows). For most Unix-based systems, including Linux and Mac OS X Server, the standard distribution "just works". It's interpreted, in that Perl programs (or scripts, as they are usually called) run directly from their source code, but actually they are processed into an internal byte-code form at the start of their execution, so while running they exist in a semi-compiled form in memory, much like Java. The upshot of this is that Perl programs tend to be fast-much slower than C programs in general, but faster then other interpreted languages (such as Python and Tcl) and often faster than Java. (The Perl interpreter itself is written in C, and its speed stems in part from careful optimization, which has evolved over time.) You'll also hear Perl and its brethren referred to as scripting languages, but they are used quite differently than AppleScript and Frontier: AppleScript is mostly used to drive other applications, whereas Perl scripts tend to do most of work on their own, like traditional programming languages. It's not a hard-and-fast division, but the two types of languages do tend to be used differently.

MacPerl, the Macintosh port of Perl, has been around for quite a while, and is quite good. It's main drawbacks are that new releases always lag behind the standard version by a significant margin, and despite the magic its porter has achieved, there are still some features which are unavailable due to the nature of the operating system-for instance, you can't fork under the Mac OS (or under Windows for that matter). The good news is that with the advent of Mac OS X and its BSD compatibility layer, you can run the standard distribution-no port necessary. The current word on the street is that MacPerl will continue to evolve as a separate package for the near future, but over time I expect that it will contract to a set of modules on top of the standard distribution. This will certainly be less work for Matthias Neeracher (the man behind the port, now working in Apple's speech group), but MacPerl has several features that I hope will survive the migration, namely a nice editor and documentation viewer, and modules allowing access to a large portion of the classic Mac API.

The MacPerl Pages
http://www.macperl.com/

So, what is Perl like? To indulge in another analogy, if C and C++ are like Latin, then Perl is definitely English. It's quirky and flexible and expressive-you can always rephrase something so that the emphasis is different but the literal meaning is the same. It can be difficult to learn in a sense, but it's actually easy to get started, and once you become comfortable with the language you can write incredibly compact code. (As an extreme example, there is a two-line version of the RSA encryption algorithm.) Perl's flexible syntax is probably its most salient feature. As a quick example, like most languages Perl has an "if", but it also has an "unless", and additionally you can switch the order of the "if" and "then" parts, much as you can in English. So, you can say, "if( ! something() ) { doWhatever(); }", just as you would in C, but you can also phrase this "doWhatever() unless something();". It's just a tiny example, but it does give you a feel for they way Perl allows you to structure your code to focus attention on it's function-in this case, it lets you emphasize the action rather than the condition. It's convenient and expressive at the same time. (Perl is also the only language which has given me the odd experience of finding source code funny-not because it did anything funny or because it was poorly written, but rather because its syntax choices were a commentary on what the program was doing. I know that sounds strange, but I'll spare you the actual code.)

As another quick example of Perl's syntactic flexibility, there are at least five different ways to quote strings (and that's a conservative count). This is handy if you need a literal with embedded quotation marks or line breaks, but you want to avoid filling it with escape characters and rendering it illegible in your source code. So, rather than writing

	"\"foo\" is a made-up word."

you can write

	q{"foo" is a made-up word.}

This flexibility comes from Perl's emphasis on the practical over the merely elegant, and its terseness lets you accomplish small tasks with small code, and quickly build tools or just one-time scripts to make your work easier. Its creator, Larry Wall, is the king of the insightful quote, and my favorite line from him underscores this point: "A perl script is correct if it gets the job done before your boss fires you." For further examples of Perl's syntax, as well as answers to common criticisms of Perl, check out the "Ten Perl Myths" article on Perl.com.

Beginning Perl : Ten Perl Myths
http://www.perl.com/pub/2000/01/10PerlMyths.html

This last example brings us to Perl's most oft-mentioned strength, its string handling. Strings are a first-class type in Perl, and actually the language doesn't distinguish between strings and numbers at all-they're both just scalars. In fact it's rather awkward in Perl to treat a string as an array of characters, as they are represented in many other languages, but you'll rarely need to do so. The language's text-handling features reflect its original application of processing, analyzing, and reporting on text-based data, and it's regular expression "sub-language" provides you with the richest set of pattern-matching tools you'll find anywhere.

Also, contrary to what you may have heard, Perl does allow you to do object-oriented programming, complete with inheritance, polymorphism, and typing. But it doesn't force you to program this way, and you can ignore these feature if you just need a quick two-line program to rename a bunch of files. For those with an Objective C background, you'll be happy to hear that Perl has the functionality of categories, although I didn't recognize their power as a design tool until I encountered Objective C. (For those unfamiliar with Objective C, categories are a language feature which allows you to add methods to a class without modifying its source code, or even having access to it.)

I would be remiss if I didn't mention one of Perl's most attractive features, which isn't actually part of the language itself: the Comprehensive Perl Archive Network, or CPAN for short. It's a mirrored archive of user-contributed code, with modules for everything from FTP and SSL to parsing HTML, XML, and SGML. (Modules are the unit of reuse in Perl, and correspond to libraries or classes in other languages.) It's a reflection of the Perl user community, which is productive and helpful and opinionated at the same time, much like the Macintosh community. The value of this code base can't be overemphasized. At the same time, I can't think of any technological reason why there is nothing even close to it for C, C++, Objective C, or Java, so I'm left with the feeling that the language itself has fostered this culture of sharing. (Of course, other languages have archive sites, but the CPAN tends to be well-organized and there is, for example, one Net::FTP module rather than 10 different implementations. For the record, I believe that Python's archive also tends to be well-managed.)

CPAN: Comprehensive Perl Archive Network
http://www.cpan.org/

Learning the Language

I hope to return to Perl in the coming months, and cover some specific applications of the language in more detail. Until the, I'll leave you with pointers to a few books designed to help you learn Perl. Also, be sure to check out the Perl.com web site, which has a wealth of resources and HTML versions of all of Perl's documentation, much of which is included with the distributions themselves. The information there is excellent but can be a bit overwhelming for someone coming to the language for the first time. For printed material, the book which jumps to mind first is MacPerl: Power and Ease, by Vicki Brown and Chris Nandor (published by Prime Time Freeware). It is indispensable if you are using the Macintosh version of Perl, but valuable even if you are not. (I hope that the authors bring us a second volume at some point.) The classic for non-Macintosh-specific Perl is Learning Perl, published by O'Reilly and Associates, who have produced a majority of the high-quality Perl titles out there. Finally, there are two new books by Manning Press which have been drawing high praise, Elements of Programming with Perl and Object Oriented Perl. The latter is not geared at beginners specifically, but takes the unique approach of treating Perl as an object-oriented language from the start.

Perl.com
http://www.perl.com/
MacPerl: Power and Ease
http://www.macperl.com/ptf_book/
The O'Reilly Perl Center
http://perl.oreilly.com/
Elements of Programming with Perl
http://www.manning.com/Johnson/
Object Oriented Perl
http://www.manning.com/Conway/

If you want to broaden your linguistic horizons further, come to the MacTech Online web pages at http://www.mactech.com/online/, where you'll find links to other fun languages.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

MacUpdate Desktop 6.0.8 - Search and ins...
MacUpdate Desktop 6 brings seamless 1-click installs and version updates to your Mac. With a free MacUpdate account and MacUpdate Desktop 6, Mac users can now install almost any Mac app on macupdate.... Read more
BitTorrent Sync 2.1.1 - Sync files secur...
BitTorrent Sync allows you to sync unlimited files between your own devices, or share a folder with friends and family to automatically sync anything. File transfers are encrypted. Your information... Read more
Quicksilver 1.3.0 - Application launcher...
Quicksilver is a light, fast and free Mac application that gives you the power to control your Mac with keystrokes alone. Quicksilver allows you to find what you need quickly and easily, then act... Read more
iWatermark Pro 1.72 - Easily add waterma...
iWatermark Pro is the essential watermarking app for professional, business, and personal use. iWatermark, is the number 1 and only watermarking tool available for all 4 platforms iPhone/iPad, Mac,... Read more
RapidWeaver 6.3 - Create template-based...
RapidWeaver is a next-generation Web design application to help you easily create professional-looking Web sites in minutes. No knowledge of complex code is required, RapidWeaver will take care of... Read more
Adobe Photoshop CC 2015 16.0.1 - Profess...
Photoshop CC 2015 is available as part of Adobe Creative Cloud for as little as $19.99/month (or $9.99/month if you're a previous Photoshop customer). Photoshop CS6 is still available for purchase (... Read more
Together 3.4.6 - Store and organize all...
Together helps you organize your Mac, giving you the ability to store, edit and preview your files in a single clean, uncluttered interface. Smart storage. With simple drag-and-drop functionality,... Read more
Monosnap 3.1.0 - Versatile screenshot ut...
Monosnap lets you capture screenshots, share files, and record video and .gifs! Capture: Capture full screen, just part of the screen, or a selected window Make your crop area pixel perfect with... Read more
Cocktail 8.5.1 - General maintenance and...
Cocktail is a general purpose utility for OS X that lets you clean, repair and optimize your Mac. It is a powerful digital toolset that helps hundreds of thousands of Mac users around the world get... Read more
Vienna 3.0.6 :5eaf312: - RSS and Atom ne...
Vienna is a freeware and Open-Source RSS/Atom newsreader with article storage and management via a SQLite database, written in Objective-C and Cocoa, for the OS X operating system. It provides... Read more

Five Nights at Freddy's 4 has Been...
In keeping with tradition, Five Nights at Freddy's 4 has made its way to the App Store with zero warning fanfare. Honestly I'd be disappointed it if happened any other way at this point. [Read more] | Read more »
Doom & Destiny Advanced (Games)
Doom & Destiny Advanced 2.3.4.0 Device: iOS Universal Category: Games Price: $.99, Version: 2.3.4.0 (iTunes) Description: ---SUPER GIGA LAUNCH DISCOUNT! Get it now for cheap or pay more later!---An additional 143 MB download is... | Read more »
Five Nights at Freddys 4 (Games)
Five Nights at Freddys 4 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: This time, the terror has followed you home. | Read more »
This Week at 148Apps: July 27-31, 2015
Winding Down July With 148Apps How do you know what apps are worth your time and money? Just look to the review team at 148Apps. We sort through the chaos and find the apps you're looking for. The ones we love become Editor’s Choice, standing out... | Read more »
You'll Want to Keep an Eye Out for...
If you're the kind of person who had fun hunting down and completing all the codex puzzles in Assassin's Creed 2, then are you ever in for a treat. The Guides looks like it's going to be a very robust collection of similarily odd, seemingly... | Read more »
Vivid Games has Announced Real Boxing 2...
The original Real Boxing was a pretty impressive bit of fisticuffs, but if the trailer Vivid Games is showing off for GamesCom is any indication Real Boxing 2 is going to be even better. [Read more] | Read more »
PAC-MAN Championship Edition DX - Tips,...
[Read more] | Read more »
Card King: Dragon Wars - Tips, Tricks an...
[Read more] | Read more »
Pac-Man Championship Edition DX has brou...
Bandai Namco has released Pac-Man Championship Edition DX on iOS and Android, which features the classic arcade gameplay that we've all grown to love. Pac-Man Championship Edition DX can be enjoyed in much shorter bursts than the arcade versions... | Read more »
Cosmonautica (Games)
Cosmonautica 1.1 Device: iOS Universal Category: Games Price: $6.99, Version: 1.1 (iTunes) Description: Cast off! Are you ready for some hilarious adventures in outer space? | Read more »

Price Scanner via MacPrices.net

MacBook 12 Retina Pundit’s New Favorite Mac
If you’re eyeing the purchase of a new 12-inch Retina MacBook, but wondering if you can live with a single USB-C port, 2011-level CPU performance, and the unorthodox keyboard, you should find... Read more
PDF Element Tool Kit For PDF For Windows 10,...
South Surrey, British Columbia based software developer Wondershare has posted an interesting infographic tracking the development of Microsoft’s flagship Windows operating system over the years,... Read more
27-inch 3.5GHz 5K iMac on sale for $81 off MS...
Adorama has the 27″ 3.5GHz 5K iMac on sale for $2218, $81 off MSRP, including a free copy of Apple’s 3-Year AppleCare Protection Plan. Shipping is free, and Adorama charges sales tax in NY & NJ... Read more
Back-to-School with Tablet and Smartphone Acc...
Belkin helps you prepare for the coming school year with a wide variety of the latest mobile and tablet accessories to outfit both grade school and college students. The line-up includes charging... Read more
11-inch MacBook Airs on sale for $100 off MSR...
Best Buy has 11-inch MacBook Airs on sale for $100 off MSRP. Choose free shipping or free local store pickup (if available). Sale prices for online orders only, in-store prices may vary: - 11″ 1.6GHz... Read more
iPad Air 2 on sale for up to $100 off MSRP
Best Buy has iPad Air 2s on sale for up to $100 off MSRP on their online store for a limited time. Choose free shipping or free local store pickup (if available). Sale prices available for online... Read more
Sale! 13-inch MacBook Pros on sale for $100 o...
B&H Photo has 13″ MacBook Pros on sale for $100 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 13″ 2.5GHz/500GB MacBook Pro: $999.99 save $100 - 13″ 2.7GHz/128GB Retina... Read more
Sale! Save $100 on 13-inch MacBook Airs this...
B&H Photo has the 13″ 1.6GHz/128GB MacBook Air on sale for $899.99 including free shipping plus NY tax only. Their price is $100 off MSRP, and it’s the lowest price available for this model.... Read more
Worldwide Tablet Market Decline Continues, Ap...
The worldwide tablet market declined -7.0% year-over-year in the second quarter of 2015 (2Q15) with shipments totaling 44.7 million units according to preliminary data from the International Data... Read more
TP-LINK TL-PA8030P KIT Powerline Featuring Ho...
Consumer and business networking products provider TP-LINK is now shipping its TL-PA8030P KIT AV1200 3-Port Gigabit Passthrough Powerline Starter Kit that expands your home’s network over its... Read more

Jobs Board

*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
Infrastructure Engineer - *Apple* /Mac - Hil...
Infrastructure Engineer - Apple /Mac Job Code: 1608 # of openings: 1 Description Our fortune 500 client is looking to hire an experienced Infrastructure Engineer to join Read more
Executive Administrative Assistant, *Apple*...
…supporting presentation development for senior leadership. * User experience with Apple hardware and software is preferred. Additional Requirements The following list Read more
*Apple* Bus Company is now hirin - Apple Bus...
Apple Bus Company is now hiring school bus drivers in the Pettis County area. Class B CDL preferred. Free training provided. No nights or weekends required. Flexible Read more
*Apple* Certified Mac Technician - Updated 6...
…and friendly, hands-on technical support to customers troubleshooting and repairing Apple /Mac products with courtesy, speed and skill. Use your problem-solving skills Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.