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About the MacPerl FAQ

Version and Date information:

• CPAN now mirrors the FAQ in the correct place.
• Clarified the operation of 8-bit character pattern matching.

The MacPerl FAQ is currently being edited and maintained by Bob Dalgleish and Bob Wilkinson. Contact them for editorial or publication information. The initial version of the FAQ was prepared by Hal Wine. The current outline and a lot of the useful words in this edition were prepared by Hal, as well.

This FAQ is intended as a supplement to the main Perl FAQ , and does not replace it.

Where to get the most recent MacPerl release:

• Use FTP to get the site registry and find the repository site nearest you. Save this information for later use when you want to get files. It saves wear and tear on the 'net and administrators everywhere.
• Use a Web browser to search for the file to download. This URL will find a (relatively local) mirror site to get your file. This URL uses a magic process to refer you to a nearby FTP site. There is also a form that will identify the most recent versions of released files and give you the URL without the search.

Where to get the most recent FAQ:

They are mirrored from MacPerlFAQ.html and MacPerlFAQ.txt, but this web-site has some name registration problems.

Versions of the FAQ can be retrieved by e-mail. Send e-mail to MacPerl@dtor.com with a subject of either:

    get FAQ

    get FAQ.html

What the FAQ covers:

The MacPerl FAQ also contains information on some unique applications of MacPerl. However, pointers to other information are more likely for these topics.

Finally, the MacPerl FAQ contains information useful in porting Perl scripts to and from the Unix environment.

What the FAQ doesn't cover:

The MacPerl FAQ is also not a tutorial. Nor is it a 100% correct authority on anything! However, we ask your indulgence by sending comments, clarifications, and revisions to one or both of the editors.

How the FAQ is organized:

Both Perl version 4 and 5 have been ported to the Mac. Much of the information in this FAQ is not unique to the Perl version being used.

Where there is a distinction or discrepancy between the versions, the applicable version will be mentioned. The most frequent difference is how package qualifications are made. In Perl4, a variable in a package was entered as $Package'variable. In Perl5, it is entered as $Package::variable, although the old form is acceptable.

The major emphasis of the FAQ has moved to MacPerl 5, so the new package syntax will be used.

Where possible, the users of MacPerl should upgrade to MacPerl5, since its extensibility and generality are very much enhanced. Perl4 scripts will run almost unimpeded under Perl5, but you can easily check for problems by setting the -w switch to flag common errors. The reference file perltraps.html in the release describes common problems.

1) General Questions

1.1) What's the most recent version of MacPerl?

Unless you already have MPW, and know its environment, you want the standalone version, hereafter called the MacPerl Application.

Perl5 introduced several powerful new technologies, including object-oriented programming to the PERL project. This allowed modules to be much more self-sufficient, yet extensible, as well as allowing system extensions. These extensions will be capitalized upon in further releases of MacPerl.

1.1.1) Perl 5

Mac_Perl_tool.bin

for the MacPerl tool

Mac_Perl_appl.bin

for the MacPerl application

Mac_Perl_tool.bin

for the MacPerl tool from Switzerland

Mac_Perl_tool.bin

for the MacPerl application from Switzerland

The source code for these versions is also available in the same directory. Consult the file Mac_Perl.info for details on which sources are needed for which version.

1.1.2) Perl 4

http://perl.com/CPAN/ports/mac/Mac_Perl_tool

for the MacPerl tool

http://perl.com/CPAN/ports/mac/Mac_Perl_appl

for the MacPerl application

ftp://ftp.switch.ch/software/mac/perl/Mac_Perl_tool

for the MacPerl tool from Switzerland

ftp://ftp.switch.ch/software/mac/perl/Mac_Perl_appl

for the MacPerl application from Switzerland

1.2) How do I install MacPerl?

1.2.1) Transferring the files:

After decompressing the archive, be sure to read all the text files in the top level directory. (Or just review them if you're upgrading.)

1.2.2) How do I unpack the stuff I got?

1.3) What Macs does MacPerl run on?

1.4) Other MacPerl resources:

1.4.1) Is there an email list for MacPerl?

1.4.2) What other useful resources are there?

Newsgroups:
• comp.lang.perl.announce
• comp.lang.perl.misc
• comp.lang.perl.modules

A searchable archive of the mailing list is available.

2) MacPerl Differences

2.1) What are the differences in functions on MacPerl?

2.2) Compatability with Unix Perl

2.2.1) Why does source preprocessing (-P) not work?

Perl5 has significantly extended the syntax and the preparation so that most preprocessing is not needed. The usual use of preprocessing is to provide manifest constants. Subroutines can be made into "bare-words", which allow what-look-to-be constant values, like ENOFILE, to be used in Perl code.

2.2.2) How do I open a pipe both to and from a command?

2.2.3) Why do %ENV changes not pass to processes that I start?

2.2.4) Why don't backticks work as they do on Unix?

Matthias has hardcoded some strings to be processed by MacPerl itself.

pwd

Current working directory.

Directory

Current working directory.

hostname

Hostname as returned by MacTCP or OpenTransport.

stty -raw

Allow single character input from the keyboard.

stty -cooked

Allow normal character input (line-oriented) from the keyboard.

See the documentation file MacPerl.Specifics in your release for up-to-date information. (This file has been superceded in MacPerl5 by the pod:macperl.html file).

For greater portability, there is a module called Cwd.pm which sets the environment variable PWD. For instance,

    use Cwd;
    chdir_init;
    $p = $ENV{'PWD'};
    ...
    chdir $newdir;
    $p = $ENV{'PWD'};

2.3) MacOS file system issues

2.3.1) How do I request an input or output file under MacPerl?

require 'StandardFile.pl';

$infilename = &StandardFile::GetFile('TEXT','ttxt','ttro' , "Default file");
$outfilename = &StandardFile::PutFile("Output file", "Default output file");

2.3.2) Why can't I detect aliases in my script?

The same is true for the results of standard file calls.

This is about to be fixed in MacPerl5r2.

2.3.3) How do I pass environment variables to my script?

property env : {"HOME", "Boot", "TEMP", "Boot:Temporary Items"}
property perlScript : "Boot:Scripting:MacPerl Ÿ:called_by_as_test.pl"
property opts : {"-n", "-x", "Boot:Scripting"}

tell application "MacPerl"
   try
      Do Script ({perlScript} & opts) mode batch environment env without extract
   on error errorMessage number errorNumber
      return errorNumber
   end try
end tell

2.3.4) How do I perform globbing in MacPerl?

        @files = <*.error>;

    opendir( DIR, ':' ) || die( "Can't open ':': $!\n" );
    @files = grep( /\.error$/, readdir( DIR ) );
    closedir( DIR );

2.4) Application additions

2.4.1) package MacPerl

2.4.2) Macintosh Toolbox interfaces

2.5) How can I compare two date strings?

2.6) How do I get MacPerl to recognize the Mac character set?

The top 128 characters which can be stored in a byte are the extended characters. However, which character is represented by which bit-pattern is font-dependent, and especially machine-dependent. Some machines do share the same extended character set e.g. Unix and MS-Windows both use the ISO-lat1 (Latin-1) character set; this is not the same as that generally used on a Macintosh.

In regular expressions, \w can be used to match against an alphanumeric character, where this set of characters is [A-Za-z0-9_]. This will not match against å, é, ü, è, or any other accented characters which are found in the extended characters of the Macintosh character set (or any other extended characters for this matter).

Portability of code (from platform to platform, and on the Macintosh from font to font) would not be compromised, if the extended characters were used within the \w, \W matches. Presently, the only way I know to do this safely is to build up a set of characters on an ad hoc basis, as and when they are needed.

2.7) How do I access Mac Resources from MacPerl?

Recently, Matthias has released Perl extensions that allow access to the Macintosh toolbox for Memory, Resources, and Apple Events. Currently, this is PowerMac-compatible only.

3) MacPerl Application

3.1) How do I package my Perl scripts?

3.1.1) Droplets:

To make a droplet, simply open your script in MacPerl, then choose "Save As". One of the "Type" options is "Droplet". The droplet is actually an application program that contains the text of your script, plus some code (about 8KB). When launched, the droplet uses Apple Events to launch MacPerl (if it isn't already running), and then sends it the script to execute.

You can reopen and change the script of droplets from within MacPerl. Subsequent "Saves" will retain the droplet file type.

If the user launches a droplet by dragging and dropping some files onto the droplet's icon in the Finder, those file names will appear as arguments to the script (i.e. they will be in @ARGV). This is one of the simplest ways to access the command line from outside of MPW.

The only downside to droplets is that users must have a complete installation of MacPerl, including any libraries that are called by your script. This means that the first application you distribute this way take over 800K. However, future droplets only take up 8K over the size of the script.

3.1.2) Standalone applications/Runtimes:

If having your users install a version of MacPerl is too onerous (required for droplets), then you can save them as a runtime application. However, not all features are supported in the runtime applications. Also, runtime versions take over 500KB per script!

Note: runtime versions do not execute any quicker. Perl (pre version 5) is always interpreted every time the script is run, period.

3.1.3) Which form should I use?

If you just send the script as a TEXT file, your friend has to install all of MacPerl application and libraries. Then, they have to start up MacPerl with your script and run it.

Runtime Modules allow your script and it's libraries to be packaged with perl into one application file. While this is convenient, it is quite large (over 500KB), and multiple scripts can't share the runtime module (2 scripts would take over 1MB). To save a script as a runtime module, debug your script, then choose "Save As". Two of the options are runtime modules: one for System 6, and the other for System 7.

The preferred approach is to save the script as a droplet. A droplet is a tiny (about 8KB) application that also contains your script. When a droplet is executed, it uses AppleEvents to have the MacPerl standalone application run the script. Also, your friend can specify the files to process by simply dropping them onto the droplet's icon in the Finder. Your friend still needs all of MacPerl installed, but doesn't have to directly interact with it.

Droplets are also created using the "Save As" menu option, and selecting the "Droplet" option. Droplets do require System 7 to work.

3.1.4) What about other files to go with the package?

The Macintosh way is to package everything that is needed into a single file using (named) resources to differentiate components. In support of this, MacPerl allows you to include CODE resources (of type XCMD or XFCN), as well as TEXT resources containing source modules, into the droplet or runtime. To get access to the CODE resource, you need to use the MacPerl::LoadExternals() function. To get access to the source modules, the require primitive searches the TEXT resources of the droplet for the module name.

3.2) Devices (printer, screen, appleevent):

3.2.1) How can I get MacPERL to dial my modem?

   ATDT 1-900-MACPERL

3.2.2) How can I keep local data files in my droplet/runtime?

3.2.3) How can I output to another window?

open(CON2, ">Dev:Console:Another Window");

3.2.4) How can I get/set AppleEvent data?

3.3) How do I develop scripts?

3.3.1) Alpha Text Editor:

You may want to consider getting the shareware text editor Alpha as well. Alpha offers a Perl editting mode in which keywords and comments are automatically colorized, subroutines are easily indexed, and the rather complete Perl man page is readily available as an online help file (indexed by section and command through a menubar popup menu) - ... Beyond that, Alpha is one of the nicest text editors (and my favorite) on any platform.

Contact W. Thomas Pollard

3.3.2) BBEdit Text Editor:

4) MacPerl MPW tool

4.1) Installation of MPW MacPerl

4.1.1) Use the following steps:

• Copy the Perl executable into a folder on the MPW path. e.g. the "MPW Folder:Tools" folder
• Copy the "lib" folder which comes with the distribution to a sensible place. e.g under "MPW Folder:Libraries" folder
• Create a UserStartup*Perl file. (The * is really the bullet character, option-8 on your keyboard.)

  This should be in the same folder as the MPW executable.

  An example "UserStartup*Perl" is given here, which uses PerlLibs for the libraries for Perl4 and Perl5libs for Perl5.

  Set PERLLIB	"{MPW}libraries:PerlLibs:"
  	Export PERLLIB
  
  Set PERL5LIB	"{MPW}libraries:Perl5Libs:"
  	Export PERL5LIB
  

4.2) Specific differences between the MPW tool and Perl under Unix

5) Special Application Areas

5.1) How can I extend the capabilities of MacPerl?

The code modules (XCMD/XFCN) developed for HyperCard may often be used in MacPerl. While there is no external documentation for which HyperCard callbacks are not implemented, most widely available code module libraries offer safe packages. See the macperl.html file in the pod directory of MacPerl for how to use MacPerl::LoadExternal().

5.1.1) Perl Modules

5.1.2) Perl Extension System (XS) and dynamic loading of extensions.

Starting with MacPerl5r2, the extension system has gotten a lot easier, and Matthias has written a number of modules that give access to the MacOS functions. These extension modules are still in beta testing, but will be made available for general release.

5.2) How do I program for the Web?

5.2.1) How do I serve Web information (CGI)?

5.2.2) How do I mail the contents of a filled in form?

5.2.3) How do I create or parse HTML documents?

If you want to do smaller versions of these tasks, then try Tom Christian's hacks for useful scripts.

5.3) Portability tricks and techniques

5.3.1) How do I know that this script is running under MacPerl?

    print "Running under MacPerl\n" if $MacPerl::Version;

    use Config;
    if ( $Config{'osname'} =~ /^macos/i ) {
        print "Running under MacPerl\n";
    }
 

Accessing file names is different between Unix and MacOS. However, Unix, MacOS and MSDOS all use hierarchical file naming, and some of the commonality has been gathered together into Perl modules for Perl5. Learn to use the portability-oriented modules, such as File::Basename.pm, and File::Path.pm.

5.3.2) How do I get input from the user of the script?

5.3.3) How do I pass parameters to the script?

#!perl -pi.BAK

If you also want to give the user a chance to enter command line options, you can use the following code fragment:

   if( $MacPerl::Version =~ /Application$/ ) {
        # we're running from the app
        local( $cmdLine, @args );
        $cmdLine = &MacPerl::Ask( "Enter command line options:" );
        require "shellwords.pl";
        @args = &shellwords( $cmdLine );
        unshift( @ARGV, @args );
    }

If your script just needs to know file names, then you can save the script as a droplet and start it by dropping the desired files onto the droplet's icon from the Finder.

In the MPW version, the command line is supplied in the same manner as on Unix. For the application, there are two choices, depending on whether or not you need just file names or also options.

If the parameters you need to supply are mostly fixed, you can also put them after the script itself, in the data portion of the script. For instance,

# Get the default parameters
 {
   my @parms = <DATA>;
    chomp(@parms);
    unshift(@ARGV, @parms);
}
...
 __END__
parm1
parm2
...

5.4) How do I know what directory the current script is in?

    $dirSep = '/';  # assume Unix
    $dirSep = ':' if $MacPerl::Version;  # change to Mac
    ($path, $app) = $0 =~ /^(.*$dirSep)?([^$dirSep]+)$/;

    use File::Basename;
    ($app, $path) = fileparse($0);

6) Misfeatures and Bugs

6.1) Misfeatures

6.1.1) Why does the here-is document not get read properly?

1. there isn't a carriage return after the final HEREIS or
2. there is a bunch of white space after the final HEREIS

    print "HEREIS\n";

6.1.2) Why does MacPerl not work with Netscape?

The latest version of ObjectSupportLib is 1.1.

6.1.3) When I try to read a particular file, why does MacPerl complain that it is "out of memory"?

Set the record separator character to "\012" using any of

    use English;
    $/ = "\012";
    $INPUT_RECORD_SEPARATOR = "\012";
    $RS = "\012";

Alternatively, translate the file using an editor or file conversion program.

6.2) Bugs

6.2.1) I can't get my droplet to run when I drop files on it?