Compared to Unix and Windows, Mac OS has one significant missing feature: it has no command line interface. Mac OS is a 100 percent windowed GUI environment.
This presents some potential problems when we consider the methods already suggested for running Perl programs.
The solution is a separate “development environment.” The MacPerl application supports both the execution of Perl scripts and the creation of the scripts in the first place. In addition to direct access to the execution process (scripts can be started and stopped from menus and key combinations), MacPerl also permits you interactive use of the Perl debugger in a familiar environment, and complete control of the environment in which the scripts are executed.
Quite aside from the simple interface problem, there are also underlying differences between text file formats, the value of the epoch used for dates and times, and even the supported commands and functions. There are ways of getting around these problems, both using your own Perl scripts and modifications and using a number of modules that are supplied as standard with the MacPerl application.
The current version of MacPerl is based on v5.004 of Perl, which makes it a couple of years old. Although the developer, Matthias Neeracher, has promised to work on a new version, there is currently no set date for a Perl 5.6 release. In fact, it’s possible that MacPerl may not be updated until Perl 6 is released toward the end of 2001.
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P e r l : T h e C o m p l e t e R e f e r e n c eRepository URL
ActiveState http://www.activestate.com/packages Jan Krynicky http://jenda.krynicky.cz/perl
Roth Consulting http://www.roth.net/perl/packages/
Achim Bohnet http://www.xray.mpe.mpg.de/~ach/prk/ppm RTO http://rto.dk/packages/
Table 2-2. PPM Repositories
For those of you interested in developing with Perl under Mac OS X, you’ll be pleased to hear that Mac OS X’s Unix layer is used to provide the same basic functionality as any Unix distribution. In fact, Mac OS X actually comes with Perl installed as standard.
Installation
Perl is available in a number of different guises, depending on what you want to do with it and how extensible and expandable you want the support modules to be. The basic distribution, “appl”, includes the MacPerl binary, all the Perl and MacPerl libraries and modules, and the documentation. The “tool” distribution works with MPW (the Macintosh Programmer’s Workshop), allowing you to develop and release Perl programs that are part of a larger overall application while presenting you with the same interface and development environment you use for C/C++ and Pascal Mac applications. Because MacPerl provides an almost transparent interface to the underlying Mac toolbox, you can use Perl and C/C++/Pascal programs and code interchangeably. The source, in the
“src” distribution, including all of the toolbox interfaces, is also available.
Installing the application is a case of downloading and decompressing the installer, and then double-clicking on the installer application. This will install all the modules, application, and documentation you need to start programming in Perl. Starting MacPerl is a simple case of double-clicking on the application.
Executing Scripts
Perl scripts are identified using the Mac OS Creator and Type codes. The MacPerl environment automatically sets this information when you save the script. In fact, MacPerl specifies three basic formats for running scripts and one additional format for use with Mac-based web servers. The different formats are outlined in Table 2-3.
FUNDAMENTALS
File Type Description
Droplet A droplet is a mini-application that consists of the original Perl script and a small amount of glue code that uses Apple events to start MacPerl, if it is not already running, and then executes the script. Using droplets is the recommended method for distributing MacPerl scripts.
To save a script as a droplet, go to Save As under the File menu, and choose Droplet in the file type pop-up at the bottom of the file dialog box.
Files dragged and dropped onto a droplet’s icon in the Finder have their names passed to the script as arguments (within@ARGV).
If you plan on distributing your scripts to other people, droplets require that the destination users have MacPerl already installed. This might make initial distributions large (about 800K), although further updates should be smaller.
Table 2-3. MacPerl Script Types
When a script is executing,STDIN,STDOUT, andSTDERRare supported directly within the MacPerl environment. If you want to introduce information on a “command line” (other than files, if you are using a droplet), you will need to use the Mac-specific toolbox modules and functions to request the information from the user.
Installing Third-Party Modules
Installation of third-party modules under MacPerl is complicated by the lack of either standard development tools or a command-line environment that would enable you to execute the normal Perl makefiles formaketools.
Scripts that rely on external modules, such as those from CPAN (especially those that require C source code to be compiled), may cause difficulties, not all of which can be easily overcome. The process for installing a third-party module is as follows:
1. Download and then extract the module. Most modules are supplied as a gzipped tar file. You can either use the individual tools, MacGzip and suntar, to extract the file, or use Aladdin System’s Stuffit Expander with the Expander Extensions.
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P e r l : T h e C o m p l e t e R e f e r e n c eFile Type Description
Stand-alone applications A stand-alone application creates a file composed of the Perl application and the script and related modules. This creates a single, “double-clickable” application that runs and executes your script.
This can be a great solution if you want to provide a single-file solution for a client, or if you want to save clients the task of installing MacPerl on their machines.
However, this is still an interpreted version. The script is not compiled into an executable, just bundled with the Perl interpreter into a single file.
Plain text file A plain text file can be opened within the MacPerl environment and executed as a Perl script. Make sure that if the script has come from another platform, the script is in Mac OS text format.
These files will not automatically execute when you double-click them. They open either the built-in editor within MacPerl or the editor you usually use for editing text files (for example, SimpleText, BBEdit, or emacs).
CGI Script This creates a script suitable for execution under many Mac-specific web servers, including the one supported by Apple’s AppleShare IP 6.0.
Table 2-3. MacPerl Script Types (continued)
TE AM FL Y
Team-Fly
®Whichever application set you use, remember to switch line-feed conversion on. This will convert the Unix-style Perl scripts into Macintosh text files, which will be correctly parsed by the MacPerl processor.
2. Read the documentation to determine whether the module or any modules on which it relies use XS or C source code. If they do, it’s probably best to forget about using the module. If you have access to the MPW toolkit, you may be able to compile the extension, but success is not guaranteed. You can also ask another MacPerl user, via the MacPerl mailing list, to compile it for you.
3. Ignore theMakefile.PLfile. Although it might run, it will probably report an error like this:
# On MacOS, we need to build under the Perl source directory or have the MacPerl SDK installed in the MacPerl folder.
Ignore it, because you need to install the Perl modules manually. Even if the Makefile.PLruns successfully, it will generate a makefile that you can’t use on the Mac without the addition of some special tools!
4. Create a new folder (if you don’t already have one) to hold your site-specific and contributed modules. This is usually located in$ENV{MACPERL}sitelib:, although you can create it anywhere, as long as you add the directory to the
@INCvariable via the MacPerl application preferences or use theuse lib pragma within a script.
Remember to create a proper directory structure if you are installing a hierarchical module. For example, when installingNet::FTP, you need to install theFTP.pmmodule into a subdirectory called Net, right below the site_perlor alternative installation location.
5. Copy across the individual Perl modules to the new directory. If the modules follow a structure, copy across all the directories and subdirectories.
6. Once the modules are copied across, try using the following script, which will automatically split the installed module, suitable for autoloading:
use AutoSplit;
my $instdir = "$ENV{MACPERL}site_perl";
autosplit("$dir:Module.pm", "$dir:auto", 0, 1, 1);
Change the$instdirand module names accordingly. See Appendix B for more details on theAutoSplitmodule.
7. Once the module is installed, try running one of the test programs, or write a small script to use one of the modules you have installed. Check the MacPerl error window. If you get an error like this,
# Illegal character \012 (carriage return).
File 'Midkemia:MacPerl ƒ:site_perl:Net:DNS:Header.pm'; Line 1
# (Maybe you didn't strip carriage returns after a network transfer?)
FUNDAMENTALS
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P e r l : T h e C o m p l e t e R e f e r e n c ethen the file still has Unix-style line feeds in it. You can use BBEdit or a similar application to convert these to Macintosh text. Alternatively, you could write a Perl script to do it!