TweetFollow Us on Twitter

MacPerl: Dev Overview

Volume Number: 14 (1998)
Issue Number: 2
Column Tag: Alternative Environments

MacPerl: A Developer's Overview

by Rich Morin

The Power of Perl, the ease of Macintosh

Overview

Perl (and, by extension, MacPerl) is a convenient and powerful language for administrative programming, CGI scripting on the World Wide Web, data analysis and filtering (such as error checking and reformatting), network programming, and more. In short, Perl can be used for almost any programming project you may have in mind.

On Unix systems, Perl is well on its way toward taking over all substantial scripting functions, supplanting traditional tools such as sh, awk, and sed. On Macintosh systems, Perl can be used just as readily (with the added attraction that there is nothing to "unlearn").

Perl was created ten years ago when its author, Larry Wall, decided that existing scripting languages were insufficiently powerful for the distributed, bug reporting project he was working on. Seeing the potential in his new tool, Larry was gracious enough to release Perl as freeware (freely redistributable software in source and binary forms).

Other programmers picked it up, tried it, liked what they saw, and suggested enhancements and modifications. In a few years, Perl grew substantially in capabilities and in adherents, and was well on its way to becoming one of the most powerful and popular computer languages in use today. Although Perl was originally written for the Unix operating system, it has since been ported to many different systems.

The recent rise in popularity of the World Wide Web has assured the popularity of Perl for some time to come. Perl is not a "strongly-hyped language" like Java, but it has shown itself to be an indispensible tool for creating and maintaining Web sites. Perl is used for CGI scripting, site management, and many other duties.

MacPerl (ported by Matthias Neeracher) has also been in existence for several years, but its popularity has not increased at the same rate, and certainly not to the level I feel it deserves. The Macintosh is a friendly, easy to use, and very popular computer system. MacPerl is an elegant and friendly Macintosh adaptation of an extraordinarily powerful (and popular) programming language. Why hasn't it taken off as quickly as Perl has?

Many potential MacPerl users are unaware that Perl (let alone a Macintosh version) exists! Most Macintosh magazines, rightly or wrongly, shy away from programming articles. Also, lacking any commercial reference material or distribution CD for MacPerl, many prospective users may have felt apprehensive about getting involved. PTF's MacPerl product (and articles like this one!) should resolve these issues, helping the community to grow substantially.

Language Summary

Perl syntax and fundamental capabilities are reminiscent of those found in C. The following bit of code, for instance, would work in either language:

printf("hello, world\n");

Ignoring a few dollar signs (indicating that the keyword is being used to name a scalar variable), most Perl code looks quite a bit like C code:

$cnt=$sum=0;
for ($i=$lo; $i<$hi; $i++) {
  if ($xyz[$i] >= 0) {
    $cnt++;
    $sum += $xyz[$i];
  }
}
printf("\$cnt=%d, \$sum=%d\n", $cnt, $sum);

Perl adds syntax and capabilities from several other languages, however. Here are some Perl commands that might be more familiar to an awk, sed, or shell scripter:

$month = $months{"Jan"};    # hash (associative array)
$upper =~ tr/[a-z]/[A-Z]/;  # character substitution
$path  =~ s@/@:@g;          # regular expression
$wd   = `pwd`;              # subprocess invocation
$cfile = "$base.c";         # variable interpolation
print "hello, world\n";     # unformatted print command

In fact, the basic Perl language offers a wealth of features unmatched in any other popular programming language, including:

  • anonymous functions, defined at run-time
  • arbitrary-length strings and data structures
  • associative (possibly persistent) arrays (hashes)
  • automatic garbage collection
  • compound data structures (such as queues of arrays)
  • dynamic storage allocation
  • file name globbing (wild card expansion)
  • late binding of data and functions
  • lists: deque, queue, indexed array, stack, and more
  • coercion between numbers and strings
  • object-oriented features (such as inheritance)
  • regular expressions for matching and substitution
  • run-time evaluation of arbitrary code
  • run-time tracing and control of external data
  • sparse arrays (indexed and hashed)

The core language is supplemented by a wide variety of predefined objects. Some of these are included in the base distribution; others can be found on the Comprehensive Perl Archive Network (CPAN), an international set of FTP mirror sites. By looking around a little, you can find objects for arbitrary-precision arithmetic, CGI scripting, genetic sequence manipulation, network administration... well, you get the idea.

Perl's language features and object definitions work together in very powerful ways. A Perl-based CGI script can, quite trivially

  • accept information from a user, checking it for validity
  • retrieve data from selected files or a remote database
  • perform arbitrary, user-specified calculations on the data
  • generate a graph from the results, storing it as an image file
  • output HTML to display the graph, with annotations

What's more, this entire operation can be performed in a demonstrably secure manner, using Perl's mechanisms for data-flow tracing, safe run-time evaluation of code, and more.

Macintosh Ease of Use

MacPerl can run as an application under the Finder or as a tool under MPW. Because most Mac users do not have MPW, the Finder version tends to dominate. I am told, however, that the MPW version acts much like any other MPW tool, supporting command-line options, ToolServer, etc.

The MacPerl application normally operates as an interactive development environment, displaying edit and interaction windows. When a MacPerl document (script) is double-clicked, it will either start up an edit/debug session or a batch program, depending on a user-definable preference. It also is possible to create "droplets", MacPerl scripts which support the Macintosh drag-and-drop protocol.

MacPerl has a built-in text editor, but it also works well with text editors such as Alpha and BBEdit. Both directly and by means of an Apple Script interface, MacPerl programs can emit and receive Apple events. Because of its interpretive nature, MacPerl provides a pleasant way to interface with the Toolbox (prototyping Dialog Boxes and such).

Although a Perl compiler is under development, current Perl implementations use a hybrid compiler-interpreter. The Perl source code is syntax-checked and parsed, but not turned into the host system's machine language. This approach allows Perl scripts to start up quickly and still run at a reasonable speed. A Perl script typically runs within a factor of three of the speed of a compiled C program.

Legal Issues

MacPerl (like Perl) is free software; it may be used, modified, and redistributed under the terms of the Perl Artistic License. This license, crafted by Larry Wall, is quite flexible. It allows commercial and non-commercial distribution of the program, with fairly minor restrictions. See the license text (included with the distribution) for specific details.

Please note that this definition of "free software" is far broader than that used by many Macintosh "freeware" applications. The fact that MacPerl is available in source code allows any interested party to look over its construction and modify its behavior. This has had a great deal to do with the growth and overall robustness of MacPerl and Perl.

Porting Issues

Perl comes from the Unix community, which does some things rather differently than the Mac OS community. Where possible, MacPerl makes accomodations, providing "reasonable" behavior. In some cases, however, Unix-derived code will have to be tweaked before it can be used. Finally, some kinds of Perl applications are totally unsuited for use on a Macintosh.

The Macintosh uses a carriage return (\015), rather than Unix's line feed (\012), to separate lines of text. MacPerl accomodates this by emitting a carriage return when a newline (\n) is specified (requests for \015 are, however, taken literally). Similarly, when reading line-oriented text, MacPerl expects a carriage return, rather than a line feed.

As a result, MacPerl does not accept line feeds as delimiters in its input programs or data files. If you want to use a Unix-derived Perl script or textual data file under MacPerl, you must first convert all of its carriage returns to newlines. This is trivial, if slightly annoying.

File naming syntax must also be converted. Slashes (/) must be changed into colons (:), full path names must be modified to include disk names, etc. In addition, if the Unix code depends on "special" files (/dev/*, /proc/*, and such), some modifications will be needed.

Unix supports preemptive multitasking, allowing (nay, encouraging) programmers to invoke separate programs whenever this seems appropriate. Perl follows in this pattern, giving programmers many ways (backquotes, exec, fork, pipes, and such) to start up other processes.

MacPerl makes a few accomodations to multitasking. Certain backquoted commands (such as `pwd`) are silently emulated, handling common Unix idioms. Some multitasking may be performed if ToolServer is present. (Of course, the requested program also must be available!) Code which depends strongly on multitasking may not port smoothly, however, even with the aid of the ToolServer. If you find such a Perl script, you should expect to rework it quite a bit before you can use it on a Mac.

Some Unix-derived Perl scripts will not port readily. Code which depends on multi-tasking may not port smoothly, even with the aid of ToolServer. Code that depends on Unix-specific system calls must be modified or eliminated.

Finally, some Perl scripts rely on binary extensions which are linked into the Perl interpreter at run time. Only a few of these extensions have been ported to MacPerl, so these scripts are unlikely to work without a lot of effort (and Perl-specific knowledge).

MacPerl Resources

The MacPerl Pages http://www.ptf.com/macperl/ are a centralized source of information on MacPerl. They contain information on MacPerl, links to online resources, forms for joining the MacPerl mailing list and submitting materials (such as code samples and war stories), and more.

All modesty aside, the definitive work on MacPerl is "MacPerl: Power and Ease" (Prime Time Freeware, 1998, ISBN 1-881957-32-2, $40 MSRP). This product combines a 350+ page introductory and reference manual with a MacPerl distribution CD-ROM. For more information, visit the Prime Time Freeware web site http://www.ptf.com/.

Perl is served by two main web sites: http://www.perl.com and http://www.perl.org. Try these sites before doing any sort of search: if you can't find what you want through one or the other of these sites, it probably doesn't exist on the Internet. Though there are quite a few books in print on Perl and related subjects, the three definitive books are published by O'Reilly & Associates:

  • Learning Perl, Second Edition, by Randal L. Schwartz, Tom Christiansen, 1996, ISBN 1-56592-284-0.
  • Programming Perl, Second Edition, by Larry Wall, et al, 1996, ISBN 1-56592-149-6.
  • Advanced Perl Programming by Sriram Srinivasan, 1997, ISBN 1-56592-220-4.

A 30-year veteran of the computer industry, Rich Morin rdm@ptf.com writes the I/Opener column for SunExpert magazine. His desktop system, Cerberus, is a three-headed Power Mac, networked to several Unixish (FreeBSD, MkLinux, Rhapsody, Solaris, and SunOS) systems.

Rich is also the president of Prime Time Freeware http://www.ptf.com/, which publishes mixed-media (book/CD-ROM) collections of freely redistributable software. PTF's Mac-specific products include MacPerl: Power and Ease and MkLinux: Microkernel Linux for the Power Macintosh. This article contains material adapted from PTF's MacPerl book.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Things 2.5.4 - 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
NeoOffice 2014.10 - Mac-tailored, OpenOf...
NeoOffice is a complete office suite for OS X. With NeoOffice, users can view, edit, and save OpenOffice documents, PDF files, and most Microsoft Word, Excel, and PowerPoint documents. NeoOffice 3.x... Read more
iPhoto Library Manager 4.2 - Manage mult...
iPhoto Library Manager allows you to organize your photos among multiple iPhoto libraries, rather than having to store all of your photos in one giant library. You can browse the photos in all your... Read more
Web Snapper 3.3.8 - Capture entire Web p...
Web Snapper lets you capture Web pages exactly as they appear in your browser. You can send them to a file as images or vector-based, multi-page PDFs. It captures the whole Web page - eliminating the... Read more
TeamViewer 10.0.41404 - Establish remote...
TeamViewer gives you remote control of any computer or Mac over the Internet within seconds, or can be used for online meetings. Find out why more than 200 million users trust TeamViewer! Free for... Read more
Ableton Live 9.1.8 - Record music using...
Ableton Live lets you create and record music on your Mac. Use digital instruments, pre-recorded sounds, and sampled loops to arrange, produce, and perform your music like never before. Ableton Live... Read more
VOX 2.5 - Music player that supports man...
VOX is a beautiful music player that supports many filetypes. The beauty is in its simplicity, yet behind the minimal exterior lies a powerful music player with a ton of features & support for... Read more
OmniFocus 2.1.2 - GTD task manager with...
OmniFocus helps you manage your tasks the way that you want, freeing you to focus your attention on the things that matter to you most. Capturing tasks and ideas is always a keyboard shortcut away in... Read more
Adobe Flash Player 17.0.0.169 - Plug-in...
Adobe Flash Player is a cross-platform, browser-based application runtime that provides uncompromised viewing of expressive applications, content, and videos across browsers and operating systems.... Read more
iMazing 1.1.3 - Complete iOS device mana...
iMazing (was DiskAid) is the ultimate iOS device manager with capabilities far beyond what iTunes offers. With iMazing and your iOS device (iPhone, iPad, or iPod), you can: Copy music to and from... Read more

Chainsaw Warrior: Lords of the Night has...
It's time to put the Darkness back in its place now that Chainsaw Warrior: Lords of the Night has officially made it to iOS. | Read more »
A World of Ice and Fire Lets You Stalk 2...
George R. R. Martin’s A World of Ice and Fire, by Random House, is a mobile guide to the epic series. The new update gives you the Journeys map feture that will let you track the movements of 25 different characters. But don't worry, you can protect... | Read more »
Gameloft Announces Battle Odyssey, a New...
Battle Odyssey, Gameloft's newest puzzle RPG, is coming to the App Store next week. Set in the world of Pondera, you will need to control the power of the elements to defend the world from evil. You'll be able to entlist over 500 allies to aid you... | Read more »
Fusion - HDR Camera (Photography)
Fusion - HDR Camera 1.0.0 Device: iOS Universal Category: Photography Price: $1.99, Version: 1.0.0 (iTunes) Description: Fusion creates HDR (high dynamic range) photos by capturing different exposures and then combining them into one... | Read more »
Sago Mini Toolbox (Education)
Sago Mini Toolbox 1.1 Device: iOS Universal Category: Education Price: $2.99, Version: 1.1 (iTunes) Description: Come build with the Sago Mini friends! Use a wrench, try a saw, or hammer some nails. From sewing hand puppets to... | Read more »
You Should Probably Grab Hitman GO While...
Hitman GO is a surprisingly cool (yet also incredibly drastic) departure from the Hitman series. It's well worth playing for any puzzle game fans out there, and at the moment you can get your hands - or garrotte if you will - on it for a mere $0.99... | Read more »
IFTTT is Bringing Do Button and Do Note...
IFTTT has announced Do Button and Do Note for the Apple Watch. Do Button lets you make your own personalized button that can connect to things like your Google Drive, control the temperature in your home with Nest Thermostat, or turn the lights on... | Read more »
How Many Days, Hours, and Minutes Are Le...
Countdown, by Yves Tscherry, is now available on the App Store. The app keeps track of countdowns to your favorite things such as someones birthday or days till the New Year. You can display the time in seconds, minutes, hours, days, weeks, months,... | Read more »
The All-New Misfit 2.0 App is Available...
Misfit has just given their app a complete overhaul. Misfit 2.0 now has a brand new interface with a sleek design and is easier to navigate. You'll be able to sync your Misfit device and look up health and fitness information faster than ever before... | Read more »
Halo: Spartan Strike (Games)
Halo: Spartan Strike 1.0 Device: iOS Universal Category: Games Price: $5.99, Version: 1.0 (iTunes) Description: Delve into 30 challenging missions through cities and jungles using a devastating arsenal of weapons, abilities and... | Read more »

Price Scanner via MacPrices.net

Clearance 13-inch 2.6GHz Retina MacBook Pro a...
B&H Photo has clearance 2014 13″ 2.6GHz/128GB Retina MacBook Pros now available for $1099, or $200 off original MSRP. Shipping is free, and B&H charges NY sales tax only. Read more
Apple refurbished 2014 13-inch Retina MacBook...
The Apple Store has Apple Certified Refurbished 2014 13″ Retina MacBook Pros available for up to $400 off original MSRP, starting at $979. An Apple one-year warranty is included with each model, and... Read more
iMacs on sale for up to $205 off MSRP, NY tax...
B&H Photo has 21″ and 27″ iMacs on sale for up to $205 off MSRP including free shipping plus NY sales tax only: - 21″ 1.4GHz iMac: $1019 $80 off - 21″ 2.7GHz iMac: $1189 $110 off - 21″ 2.9GHz... Read more
Sale! 16GB iPhone 5S for $1 with service
Best Buy is offering 16GB iPhone 5Ss for $1.00 with 2-year activation at a participating cellular provider. Choose free home shipping and activation, or buy online and activate during in-store pickup... Read more
Apple refurbished 2014 MacBook Airs available...
The Apple Store has Apple Certified Refurbished 2014 MacBook Airs available starting at $679. An Apple one-year warranty is included with each MacBook, and shipping is free. These are currently the... Read more
27-inch 3.5GHz 5K iMac on sale for $2349, sav...
 Adorama has the 27″ 3.5GHz 5K iMac in stock today and on sale for $2349 including free shipping plus NY & NJ sales tax only. Their price is $150 off MSRP. For a limited time, Adorama will... Read more
Save up to $380 on an iMac with Apple refurbi...
The Apple Store has Apple Certified Refurbished iMacs available for up to $380 off the cost of new models. Apple’s one-year warranty is standard, and shipping is free: - 27″ 3.5GHz 5K iMac – $2119 $... Read more
iFixIt Teardown Awards 12-IInch Retina MacBoo...
iFixIt has posted its illustrated teardown of the new 12-inch MacBook Retina. They note that this new MacBook is less than half the thickness of the last Apple notebook called just “MacBook” back in... Read more
13-inch 2.5GHz MacBook Pro (refurbished) avai...
The Apple Store has Apple Certified Refurbished 13″ 2.5GHz MacBook Pros available for $829, or $270 off the cost of new models. Apple’s one-year warranty is standard, and shipping is free: - 13″ 2.... Read more
Faithful iPad 2 Gets A Second Career In Retir...
Finally, after four months’ transition, I handed my faithful old 2011 iPad 2 off to my wife at the end of March and switched whole-hog to using the iPad Air 2 I bought back in November. I’d found... Read more

Jobs Board

*Apple* Solutions Consultant - Retail Sales...
**Job Summary** As an Apple Solutions Consultant (ASC) you are the link between our customers and our products. Your role is to drive the Apple business in a retail Read more
*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
*Apple* Retail - Multiple Positions - Apple,...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
*Apple* Solutions Consultant - Retail Sales...
**Job Summary** As an Apple Solutions Consultant (ASC) you are the link between our customers and our products. Your role is to drive the Apple business in a retail Read more
*Apple* TV Live Streaming Frameworks Test En...
**Job Summary** Work and contribute towards the engineering of Apple 's state-of-the-art products involving video, audio, and graphics in Interactive Media Group (IMG) at Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.