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

Google Earth 7.1.7.2602 - View and contr...
Google Earth gives you a wealth of imagery and geographic information. Explore destinations like Maui and Paris, or browse content from Wikipedia, National Geographic, and more. Google Earth combines... Read more
ClamXav 2.10 - Virus checker based on Cl...
ClamXav is a popular virus checker for OS X. I have been working on ClamXav for more than 10 years now, and over those years, I have invested a huge amount of my own time and energy into bringing... Read more
Tweetbot 2.4.4 - Popular Twitter client.
Tweetbot is a full-featured OS X Twitter client with a lot of personality. Whether it's the meticulously-crafted interface, sounds and animation, or features like multiple timelines and column views... Read more
Sierra Cache Cleaner 11.0.1 - Clear cach...
Sierra Cache Cleaner is an award-winning general purpose tool for macOS X. SCC makes system maintenance simple with an easy point-and-click interface to many macOS X functions. Novice and expert... Read more
Things 2.8.8 - Elegant personal task man...
Things is a task management solution that helps to organize your tasks in an elegant and intuitive way. Things combines powerful features with simplicity through the use of tags and its intelligent... Read more
Remotix 4.1 - Access all your computers...
Remotix is a fast and powerful application to easily access multiple Macs (and PCs) from your own Mac. Features Complete Apple Screen Sharing support - including Mac OS X login, clipboard... Read more
Airfoil 5.1.2 - Send audio from any app...
Airfoil allows you to send any audio to AirPort Express units, Apple TVs, and even other Macs and PCs, all in sync! It's your audio - everywhere. With Airfoil you can take audio from any... Read more
Firefox 49.0.1 - Fast, safe Web browser.
Firefox offers a fast, safe Web browsing experience. Browse quickly, securely, and effortlessly. With its industry-leading features, Firefox is the choice of Web development professionals and casual... Read more
Default Folder X 5.0.7 - Enhances Open a...
Default Folder X attaches a toolbar to the right side of the Open and Save dialogs in any OS X-native application. The toolbar gives you fast access to various folders and commands. You just click on... Read more
Safari Technology Preview 10.1 - The new...
Safari Technology Preview contains the most recent additions and improvements to WebKit and the latest advances in Safari web technologies. And once installed, you will receive notifications of... Read more

4 games like Burly Men at Sea to inspire...
Burly Men at Sea is out today and it looks a treat. It tells the tale of three Scandinavian fishermen who leave the humdrum of their daily lives to go exploring. It’s a beautiful folksy story that unfurls as you interact with the environment... | Read more »
3 reasons you need to play Kingdom: New...
Developed by a tag team of indie developers - Thomas "Noio" van den Berg and Marco "Licorice" Bancale - Kingdom is a vibrant medieval fantasy adventure that casts players as a king or queen who must expand their empire by exploring the vasts lands... | Read more »
JoyCity have launched a brand new King o...
Great news for all of you Game of Dice fans out there - JoyCity have just released a brand new limited edition pack with a really cool twist. The premise of Game of Dice is fairly straightforward, asking you to roll dice to navigate your way around... | Read more »
Burly Men at Sea (Games)
Burly Men at Sea 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: Burly Men at Sea is a folktale about a trio of large, bearded fishermen who step away from the ordinary to seek adventure. | Read more »
3 tips for catching the gnarliest waves...
Like a wave breaking on the shore, Tidal Rider swept its way onto the App Store charts this week settling firmly in the top 10. It’s a one-touch high score-chaser in which you pull surfing stunts while dodging seagulls and collecting coins. The... | Read more »
The beginner's guide to destroying...
Age of Heroes: Conquest is 5th Planet Games’ all new turn-based multiplayer RPG, full of fantasy exploration, guild building, and treasure hunting. It’s pretty user-friendly as far as these games go, but when you really get down to it, you’ll find... | Read more »
Infinite Tanks (Games)
Infinite Tanks 1.0.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.0 (iTunes) Description: | Read more »
Agatha Christie - The ABC Murders (FULL)...
Agatha Christie - The ABC Murders (FULL) 1.0 Device: iOS Universal Category: Games Price: $6.99, Version: 1.0 (iTunes) Description: Agatha Christie: The ABC Murders Your weapon is your knowledge. Your wits will be put to the ultimate... | Read more »
HeadlessD (Games)
HeadlessD 1.0 Device: iOS Universal Category: Games Price: $.99, Version: 1.0 (iTunes) Description: HeadlessD is hand-painted dungeon crawler with intuitive touch controls and NO in-app purchases. | Read more »
Leaf for Twitter (Social Networking)
Leaf for Twitter 1.0.1 Device: iOS iPhone Category: Social Networking Price: $4.99, Version: 1.0.1 (iTunes) Description: | Read more »

Price Scanner via MacPrices.net

Apple refurbished 2015 13-inch MacBook Airs a...
Apple has Certified Refurbished 2015 13″ MacBook Airs available starting at $759. An Apple one-year warranty is included with each MacBook, and shipping is free: - 2015 13″ 1.6GHz/4GB/128GB MacBook... Read more
MacBook Airs on sale for up to $100 off MSRP
B&H Photo has 13″ and 11″ MacBook Airs on sale for up to $100 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 11″ 1.6GHz/128GB MacBook Air: $799 $100 MSRP - 11″ 1.6GHz/256GB... Read more
Apple refurbished 12-inch 128GB iPad Pros ava...
Apple has Certified Refurbished 12″ Apple iPad Pros available for up to $160 off the cost of new iPads. An Apple one-year warranty is included with each model, and shipping is free: - 32GB 12″ iPad... Read more
Phone2Action Unveils New Voter Turnout Techno...
Phone2Action, a leading digital advocacy platform, today launched its Tech to Vote Civic Action Center digital advocacy and communications platform on National Voter Registration Day September 27.... Read more
Apple & Deloitte Team Up to Help Business...
Apple and international professional services firm Deloitte have announced a partnership to help companies quickly and easily transform their workflow dynamics by maximizing the power, ease-of-use,... Read more
Chop Commute – See Traffic and Drive Times on...
Shrewsbury, Massachusetts based Indie developer, InchWest has released Chop Commute 1.61, a Mac app that takes the guesswork out of daily commute by showing real-time traffic and drive times right on... Read more
12-inch 32GB WiFi iPad Pros on sale for $50 o...
B&H Photo has 12″ 32GB WiFi Apple iPad Pros on sale for $50 off MSRP, each including free shipping. B&H charges sales tax in NY only: - 12″ Space Gray 32GB WiFi iPad Pro: $749 $50 off MSRP -... Read more
Recent price drops on refurbished iPad minis...
Apple recently dropped prices on several Certified Refurbished iPad mini 4s and 2s as well as iPad Air 2s. An Apple one-year warranty is included with each model, and shipping is free: - 16GB iPad... Read more
Apple refurbished Mac minis available startin...
Apple has Certified Refurbished Mac minis available starting at $419. Apple’s one-year warranty is included with each mini, and shipping is free: - 1.4GHz Mac mini: $419 $80 off MSRP - 2.6GHz Mac... Read more
13-inch 2.5GHz MacBook Pro available for $928...
Overstock has the 13″ 2.5GHz MacBook Pro available for $927.99 including free shipping. Their price is $171 off MSRP. 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
Restaurant Manager (Neighborhood Captain) - A...
…in every aspect of daily operation. WHY YOU'LL LIKE IT: You'll be the Big Apple . You'll solve problems. You'll get to show your ability to handle the stress and Read more
*Apple* Wireless Lead - T-ROC - The Retail O...
…wealth of knowledge in wireless sales and activations to the Beautiful and NEW APPLE Experience store within MACYS.. THIS role, APPLE Wireless Lead, isbrandnewas Read more
Lead *Apple* Advocate - T-ROC - The Retail...
…Company, is proud of its unprecedented relationship with our partner and client, APPLE ,in bringing amazing" APPLE ADVOCATES"to "non" Apple store locations. Read more
*Apple* Advocate - T-ROC - The Retail Outsou...
…Company, is proud of its unprecedented relationship with our partner and client, APPLE ,in bringing amazing" APPLE ADVOCATES"to "non" Apple store locations. Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.