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

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
Kodi 15.1.rc1 - Powerful media center to...
Kodi (was XBMC) is an award-winning free and open-source (GPL) software media player and entertainment hub that can be installed on Linux, OS X, Windows, iOS, and Android, featuring a 10-foot user... Read more
Bookends 12.5.8 - Reference management a...
Bookends is a full-featured bibliography/reference and information-management system for students and professionals. Access the power of Bookends directly from Mellel, Nisus Writer Pro, or MS Word (... Read more
Chromium 44.0.2403.125 - Fast and stable...
Chromium is an open-source browser project that aims to build a safer, faster, and more stable way for all Internet users to experience the web. Version 44.0.2403.125: This release contains a number... 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 »
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 »
Rescue humanity from a Demon horde in An...
Angel Stone is Fincon's follow up to the massively successful Hello Hero and is out now on iOS and Android. You play as a member of The Resistance, a group of mighty human warriors who have risen up in defiance of the Demon horde threatening to... | Read more »
Gallery Doctor (Photography)
Gallery Doctor 1.0 Device: iOS iPhone Category: Photography Price: $2.99, Version: 1.0 (iTunes) Description: Free up valuable iCloud and iPhone storage with Gallery Doctor, the only iPhone cleaner that automatically identifies the... | 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.