Chris Nandor

NAME

Mac::Glue - Control Mac apps with Apple event terminology

SYNOPSIS

        use Mac::Glue;
        my $glue = Mac::Glue->new('Finder');
        $glue->prop('System Folder')->open;
        # see rest of docs for lots more info

DESCRIPTION

"Mac::Glue does AppleScript so you don't have to."

If you have MacPerl earlier than 5.6, you should have the latest cpan-mac distribution:

        http://sf.net/projects/cpan-mac/

For Mac OS X, you should have the latest Mac::Carbon distribution:

        http://projects.pudge.net/

Also see projects.pudge.net for more information, support, CVS, etc.

Mac OS apps speak to each other with a lingua franca called Apple events. The most common way to do Apple events (aside from doaing them in a precompiled application with C, Pascal, etc.) is with AppleScript. Other languages can do Apple events too, like Frontier and even Python. But we like Perl.

MacPerl has for a few years had an interface to Apple events, with the Mac::AppleEvents module, which is the basis for everything we'll do here. Mac::AppleEvents::Simple was made to simplify the process of doing Apple events in MacPerl, but even that can be too much trouble to use. One has to find out the class and event IDs, find out the keywords and data types for each parameter, etc.

So the vision was born for a framework that wouldn't take much significant work. An application's AETE resource would provide the names to match to the cryptic four-character codes we had been using. Compare.

Raw Mac::AppleEvents method
        use Mac::AppleEvents;
        use Mac::Errors '$MacError';

        $evt = AEBuildAppleEvent('aevt', 'odoc', typeApplSignature, 'MACS',
                kAutoGenerateReturnID, kAnyTransactionID,
                "'----': obj{want:type(prop), from:'null'()," . 
                "form:prop, seld:type(macs)}"
        ) or die $MacError;
        $rep = AESend($evt, kAEWaitReply) or die $MacError;

        AEDisposeDesc($evt);
        AEDisposeDesc($rep);
Easier Mac::AppleEvents::Simple method
        use Mac::AppleEvents::Simple;
        do_event(qw(aevt odoc MACS),
                "'----': obj{want:type(prop), from:'null'()," . 
                "form:prop, seld:type(macs)}"
        );
Cool Mac::Glue method
        use Mac::Glue;
        my $glue = Mac::Glue->new('Finder');
        $glue->open( $glue->prop('System Folder') );

The latter is much simpler to understand, to read, to write. It leverages the user's understanding of AppleScript. And it is just more natural.

There are downsides. Mac::Glue is less powerful than the Mac::AppleEvents raw interfaces, because it offers less flexibility in how events are called. It is also slower to start a script, because the glue structures need to be loaded in. However, once a script has started, a difference in speed from the raw interfaces should be minimal (though not a lot of testing has been done on that). With the code above, on a PowerBook G3/292, running Mac OS 8.6:

    Benchmark: timing 100 iterations of glue, glue2, raw, simple...
          glue: 10 secs ( 9.98 usr  0.00 sys =  9.98 cpu)
         glue2:  8 secs ( 8.35 usr  0.00 sys =  8.35 cpu)
           raw:  8 secs ( 7.88 usr  0.00 sys =  7.88 cpu)
        simple:  7 secs ( 7.50 usr  0.00 sys =  7.50 cpu)

The "glue2" entry is the same as "glue" entry, but it creates a glue object only once instead of each time through, cutting down on the overhead. It appears that Mac::Glue is a bit slower than the other methods, but not substantially, and it is cooler and easier. The one place where performance is the biggest problem is on initial execution of the program, but once it starts it is plenty fast. We'll work to cut down that start time, too.

So, now that you are convinced this is cool, let's continue.

Mac OS X

Mac OS X is supported by Mac::Glue now. Note that some glues and methods will behave differently, due to differences in application implementation (for example, the Finder's "clean up" event is not supported in Mac OS X at this writing).

Creating a Glue

In order to script an application with Mac::Glue, a glue must be created first. For that, the application is passed to the gluemac script. A distribution called Mac::AETE, created by David Schooley, is used to parse an application's AETE resource, and the glue is written out to a file using Storable, DB_File, and MLDBM. Glues are saved in $ENV{MACGLUEDIR} (which is defined when Mac::Glue is used if it is not defined already). By default for MacPerl, glues are stored in :site_perl:Mac:Glue:glues:, or in ./Glue/glues relative to Glue.pm for Unix (Mac OS X).

All glues have access to the global scripting additions and dialect information. Glues for these must be created as well, and are created with the gluescriptadds and gluedialect programs, which are similar to the gluemac program. They are saved in the directories $ENV{MACGLUEDIR}additions and $ENV{MACGLUEDIR}dialects.

Along with the glue file is a POD file containing documentation for the glue, listing all the events (with parameters), classes (with properties), and enumerators, and descriptions of each.

Using a Glue

The first thing you do is call the module.

        use Mac::Glue;

Then you create an object for your app by passing the new function the name of the glue (you may include or omit underscores in the name if you like).

        my $glue = Mac::Glue->new('My App');  # or My_App

You can also pass in additional parameters for the type of target to use.

  • Bundle ID (Mac OS X only)

            Mac::Glue->new('My App', bundle => 'com.example.MyApp');
  • Process Serial Number

            Mac::Glue->new('My App', psn => $psn);
  • Process ID (Mac OS X only)

            Mac::Glue->new('My App', pid => $pid);
  • Application path

            Mac::Glue->new('My App', path => $path_to_file_or_bundle);
  • AppleTalk (Mac OS only)

            Mac::Glue->new('My App', ppc => 'My App Name',
                    'Server Name', 'Zone');
  • Application URL

            Mac::Glue->new('My App', eppc => 'My App Name', 'mac.example.com',
                    $uid, $pid, $user, $pass);

    UID, PID, user, pass are optional (and ignored entirely for Mac OS 9). It is recommended to use the Keychain to handle user/pass (just omit them, and you'll be prompted in a dialog box for them, with an option for the Keychain to remember them).

    UID and PID are used if there's more than one target application, though these don't currently work in my tests.

Addresses can be changed after the fact:

        $glue->ADDRESS(eppc => 'My App Name', 'mac.example.com');

And to reset the address to the default, call the method with no parameters:

        $glue->ADDRESS;

Once you have your glue set up, you start calling events, as they are documented in the POD file for the glue. The events can be called case-insensitively, with the exception of those that match the names of the special methods (see "Special parameters and methods"). In that case, since the special methods are in all caps, the event methods can be called case-insensitively except for all caps. e.g., for an event named reply, it could be called with:

        $glue->Reply;
        $glue->reply;
        $glue->RePLY;

However, it could not be called with $glue->REPLY, since that is reserved.

All applications respond to events differently. Something that works for one application might not work for another, so don't use any of these examples as a way you should script a specific application. They are just hyopthetical examples, for the most part.

Events sometimes accept parameters, sometimes they don't. The primary parameter of most events is a special parameter called the direct object parameter. In your event call, pass the data for that parameter first:

        $glue->open($file);

Other parameters must be named and must be provided as key-value pairs, with the key as the name of the parameter, and the value as the parameter's data:

        $glue->open($file, using => $myapp);

Note that the direct object parameter is the only parameter that doesn't need a name in front of it, and must come first in the list if it is supplied at all.

Mac::Glue will attempt to coerce passed data into the expected type. For example, if open expects an alias, the file specification in $file will be turned into an alias before being added to the event.

You can override this behavior with the param_type function. If open expects an alias (typeAlias), but you want to pass text, you can do:

        $glue->open( param_type(typeChar, $path) );

Each datum can be a simple scalar as above, an AEDesc object, an Mac::AEObjDesc object (returned by obj, prop, and event methods), an Mac::AEEnum object (returned by the enum function, see EXPORT), or an array or hash reference, corresponding to AE lists and records. In this example, we nest them, with an arrayref as one of the values in the hashref, so the AE list is a datum for one of the keys in the AE record:

        $glue->make(new => 'window', with_properties =>
                { name => "New Window", position => [100, 200] });

The words "name" and "position" will be changed into the proper corresponding AE IDs. And on return, record keys will be changed back from the AE IDs into the English words.

Events return direct object parameters, turned into suitable data for use in the program. Aliases are resolved into file specifications, AE records and lists are turned into Perl hashes and arrays (recursively, for nested lists), etc.

        my @urls = $sherlock->search_internet('AltaVista',
                for => 'Mac::Glue');

AE objects (which will be discussed later) are returned as Mac::AEObjDesc objects, so they may be used again by being passed back to another event.

        my $window_object = $glue->get( window => 1 );
        $glue->save($window_object);

This allows AppleScript-like loops:

        my @selection = $glue->get( $glue->prop(selection => of => window) );
        my @owners;
        for my $item (@selection) {
                push @owners, $glue->get( $glue->obj(cell => 'Owners' => $item) );
        }

Some objects may allow an easy way to get a human-readable form, with the as parameter:

        my $item = $glue->get( file => 1, as => 'string' );

Errors are returned in the special variable $^E, which should be checked immediately after an event call (for portability with Mac OS X, use $MacError instead for the value):

        $glue->close(window => 1);
        if ($^E) {
                warn "Couldn't close window: $MacError\n";
        }

Or, if a value is expected and none is returned:

        my $file = $glue->choose_file('Select a file, please.')
                or die "No file chosen: $MacError";

Checking $^E only works if the error returned is an error number. If it isn't, the actual error is available from the reply event, which can be accessed by using the RETOBJ parameter (described below in "Special parameters and methods").

You can also handle errors with the ERRORS handlers (also described below in "Special parameters and methods").

Creating object specifier records

This is one of the more complex parts of Apple events, and it is only partially implemented (though full implementation is expected eventually, and most of it is implemented now).

Object specifier records are created by the obj method, and have four components to them.

class
container
form
data

The class and data are passed as key-value pairs, like in AE records or parameter lists. The form and the type of the data are determined by the glue data or a good guess. The container is determined by the order of the key-value pairs: each pair is contained by the pair or object that follows it.

        my $obj = $glue->obj(file => 'foo', folder => 'bar', disk => 'buz');

So you have three pairs. The key of each pair ("file", "folder", "disk") is the class. The value of each pair ("foo", "bar", "baz") is the data. Because the data are each text, the form defaults to formName, and the data type defaults to typeChar (TEXT). If the data is a number, then the form would be formAbsolutePosition, and the data type would be typeLongInteger.

So that leaves only the container. Each pair is contained by the pair following it. The disk contains the folder, the folder contains the file. The disk has no container (its container is null).

Easy, right? I hope so. That's the idea. But let's go back to the forms, since that is the only tough part left.

The primary forms are types, names, unique IDs, absolute positions, relative positions, tests, and ranges. Normally, text data has form name and type TEXT. Integer data has absolute position form, and integer type. The obj_form function (see EXPORT) accepts three parameters, which allows you to set the form and data, or form, type, and data, in case you want to send data different from how Mac::Glue would guess.

These two are the same, since in the second case, the other is assumed:

        use Mac::Glue ':glue';

        $obj1 = $glue->obj(window =>
                obj_form(formAbsolutePostion, typeLongInteger, 1));

        $obj2 = $glue->obj(window => 1);

Special constants are exported that specify relative positions and absolute positions.

        $first  = $glue->obj(file => gFirst, property => 'Desktop');
        $second = $glue->obj(file => gNext, $first);

        for ($first, $second) {
                print $glue->get($_, as => 'string');
        }

of and in are synonyms of property:

        $glue->obj(file => gFirst, property => 'Desktop');
        $glue->obj(file => gFirst, of => 'Desktop');
        $glue->obj(file => gFirst, in => 'Desktop');

The "as" parameter above has a form of type, such as:

        obj_form(formPropertyID, typeType, 'string');

Then "string" is turned into a four-character ID behind the scenes (in this case, it is "TEXT").

A special method called prop is for specifying properties. These are equivalent:

        $glue->obj(property => 'Desktop');
        $glue->prop('Desktop');

Descriptor types for object specifier records

Property IDs

Normally, the glue will know a property is expected and coerce whatever string you provide into its four-character ID. Sometimes obj_form(formPropertyID, typeType, 'property_name') may be appropriate.

Name

Just pass the data as text. If there is some ambiguity, you may explicitly use obj_form(formName, typeChar, 'string').

Unique IDs

Could be any type. Usually you will need to use obj_form, else name or absolute position will be used. Use obj_form(formUniqueID, TYPE, DATA).

Absolute position

As discussed above, if it is an index number, you can just pass the number, as in window => 1, or you can explicitly mark it with window => obj_form(formAbsolutePosition, typeLongInteger, 1).

For other absolutes, you may use constants, such as window => gLast. Choices are gFirst, gMiddle, gLast, gAny, gAll.

These are just shortcuts for explicit forms like obj_form(formAbsolutePosition, typeAbsoluteOrdinal, kAEAll).

Note that if there is a plural form of the class name, you may use it to mean the same thing as "class => gAll". These are all the same:

        $f->obj(files => of => 'System Folder');
        $f->obj(files => gAll, of => 'System Folder');
        $f->obj(file => gAll, of => 'System Folder');
Relative position

Similar to absolute position, but an additional object must be specified, such as file = gNext, file => gMiddle>, which would return the file after the middle file. Available constants are gNext and gPrevious.

The explicit form is obj_form(formRelativePosition, typeEnumerated, kAENext).

Ranges

The range function accepts two arguments, the start and stop ranges.

        range(START, STOP)

(See EXPORT.)

Each can be a number index, an absolute position constant, a string, or another data type passed with obj_form. Here are a few ways to specify files in the System Folder:

        $f->obj(files => range(1, 5), of => 'System Folder');
        $f->obj(files => range(1, "System"), of => 'System Folder');
        $f->obj(files => range("Finder", "System"), of => 'System Folder');
        $f->obj(files => range(gFirst, "System"), of => 'System Folder');
Whose tests

The whose function accepts either logical records or comparison records.

        # comparison record
        $f->obj(CLASS => whose(CLASS => VALUE, OPERATOR, VALUE));
        $f->obj(CLASS => whose(PROPERTY, OPERATOR, VALUE));

(See EXPORT.)

PROPERTY and CLASS => VALUE work like prop() and obj(). The PROPERTY form is the same as property => VALUE.

OPERATOR is contains, equals, begins_with, ends_with, l_t, l_e, g_t, or g_e. VALUE is the value to compare to.

        # files whose name begins with "foo"
        $f->obj(files => whose(name => begins_with => 'foo'));

        # rows whose first cell equals "bar"
        $f->obj(rows => whose(cell => 1 => equals => 'bar'));

Then there is the logical record type, for use when more than one comparison record is needed.

        # logical record
        $f->obj(CLASS => whose(OPERATOR, LIST));

OPERATOR is AND, OR, or NOT. LIST is any number of other logical records or comparison records, contained in anonymous arrays. So you can join any number of records together:

        # words where it contains "e" and it begins with "p" and it does not end with "s"
        $aw->obj(
                words => whose(AND =>
                        [it => contains => 'e'], [it => begins_with => 'p'],
                        [NOT => [it => ends_with => 's']]
                ), $text)

Note how each logical record and comparison record following each logical operator is in an anonymous array. Also not how the special word "it" refers to the object being examined.

There's one more record type that works similarly to the above object specifier records, but is not exactly the same thing. It's called an insertion location record, and is created like this:

        location(POSITION[, OBJECT])

(See EXPORT.)

POSITION is a string, and can be one of before, after, beginning, or end. front is a synonym for beginning, and back and behind are synonyms for after.

OBJECT is the object to be positioned against, and will be the null object if not supplied.

        my $aw = new Mac::Glue 'AppleWorks';
        my $text = $aw->prop(text_body => document => 1);
        $aw->activate;

        # note null object in location()
        $aw->make(new => 'document', at => location('front'));
        $aw->set($text, to => "foo bar buz baz.");

        $aw->move(
                $aw->obj(word => 4 => $text),
                to => location(after => $aw->obj(word => 2 => $text))
        );

Shortcuts for object specifier records

Object specifier records objects in Mac::Glue can be called with any method from the record's parent glue, and it will be passed to that method as the direct object. Examples:

        $tracks = $itunes->obj(tracks => $library);
        $tracks = $library->obj('tracks');

        @tracks = $itunes->get($tracks);
        @tracks = $tracks->get;

        $itunes->play($tracks[0]);
        $tracks[0]->play;

In the first example, the record $library is the direct object in the obj() method, and so it can be flipped around with $library-obj('tracks')>.

Then, in the second example, the resulting record, $tracks, is called as the direct object of get().

Similar is the third example, where the track we wish to play is the direct object of play().

Data from object specifier records

Sometimes data will be returned from an application in an object specifier record, and you want to get the data underneath. This isn't usually necessary, but it came up in the case of iPhoto, where iPhoto would return a 64-bit integer, but want a 32-bit integer or float to be sent back to it.

Normally, just using the object specifier record the app returned should be sufficient, but in this case, it isn't.

Example:

        # how it should work
        my $sel = $iphoto->prop('selection');
        for my $photo ($sel->get) {
                # ... do stuff with $photo
        }

        # how it works
        my $sel = $iphoto->prop('selection');
        for my $photo ($sel->get) {
                my $id = $photo->getdata; # get data in usable form
                my $newphoto = $iphoto->obj(photo =>
                        obj_form(formUniqueID, typeFloat, $id)
                );
                # ... do stuff with $newphoto
        }

Another workaround is to merely act on the object without fetching it.

        my $sel = $iphoto->prop('selection');
        # ... do stuff with $sel

Results may vary.

Special parameters and methods

Special parameters can be passed in the event which control certain aspects of the event call's behavior. They can be passed as parameters (affecting only the one event), or called as methods (which affect every call made from that object). They are all upper case.

        $glue->REPLY(1);                # wait for reply on all events
        $glue->close(REPLY => 0);       # don't wait for this one event
REPLY

Boolean, for whether or not to wait for a reply. Default is to wait.

MODE

Set other modes, such as kAENeverInteract. This value is OR'd together with the REPLY value. Default is kAECanSwitchLayer.

SWITCH

Switch to the application being called. Usually more efficient to use the activate event:

        $glue->activate;
PRIORITY

Set the event priority. Default is kAENormalPriority.

TIMEOUT

Number of seconds to wait before timing out. Default is a couple hundred thousand seconds or so.

RETOBJ

Boolean, for whether or not the event call will return the direct object data (the default), or a Mac::AppleEvents::Simple object, containing references to the actual event and reply, so you can do more advanced things with the data if you want to.

ERRORS

A subroutine reference that will handle any errors (that is, will be executed only if $^E is true) after the event is executed. Your handler will be passed a hashref as its first argument, containing basic information about the event and error, followed by whatever arguments were passed to the event. The hashref keys are:

        _glue     actual glue object
        _event    Mac::AppleEvents::Simple object that produced the error
        glue      name of the application glue
        event     name of the event
        errs      error string
        errn      error number
        line      line of the error
        filename  filename of the error
        package   package of the error

If ERRORS is passed a value of 1, then the default error handler will be used. It is the same as the example error handler below.

Example:

        sub error_handler {
                my($err, @args) = @_;
                my $args = join ', ', @args;
                warn sprintf("%s->%s(%s) event failed:\n%s (%d)\n%s\n",
                        $err->{glue}, $err->{event}, $args,
                        $err->{errc}, $err->{errn}, $err->{errs}
                );
        }

        $finder->open(
                $finder->obj( item => 'HD' ), # nothing named HD in Finder
                ERRORS => \&error_handler
        );

Result:

        Finder->(DOBJ, Mac::AEObjDesc=HASH(0xb0dc30)) event failed (-1728):
        errAENoSuchObject
        e.g.,: specifier asked for the 3rd, but there are only 2. Basically,
        this indicates a run-time resolution error.
launch

launch() will launch the app, if it is not already launched. This is rarely necessary, as it is done automatically when needed.

version

version() gets the application's version, unpacking the data as necessary, because the data is sometimes returned in a binary format.

app_process

app_process() returns the reference to the application process object in the System Events application. See gluedoc System_Events for more information. Example to hide the application:

        $glue->app_process->prop('visible')->set(to => 0);

Editing a Glue

There is an included droplet, glueedit, for editing glues. Drop a created glue on the droplet, and it will make a text file on the Desktop. Edit it, and then drop the text file back on the droplet. Be careful; this obviously can be dangerous. If you break something, you can use gluemac to recreate the original glue, of course.

Why would you edit a glue? Well, sometimes AETE resources are wrong. :)

EXPORT

Mac::Glue has two export sets. glue exports the constants and functions beginning with "glue" listed in "Creating Object Specifier Records", as well as the functions obj_form, enum, location, range, and whose. all exports everything from Mac::AppleEvents and Mac::AppleEvents::Simple, including all functions and constants. Nothing is exported by default.

        use Mac::Glue ':glue';  # good for most things
        use Mac::Glue ':all';   # for more advanced things

TIPS

Hide background apps

        use Mac::Glue;
        use Mac::Apps::Launch;
        $a = new Mac::Glue 'Acrobat Exchange';
        $a->launch;
        Hide($a->{ID});

        # now do your thing ...

(This won't work on Mac OS X for now.)

Updating Glues

Use the -c and -r flags in gluemac to update glues, either updating all (with -r) glues, or just those apps with versions different from those stored in the glues.

To update scripting additions or the dialect (which probably should be done when adding new scripting additions, or updating the system software), run gluescriptadds and gluedialect.

Scripting Addition Maintenance

If you have a lot of scripting additions, it can slow down Mac::Glue (on startup) and take up more RAM. Same thing goes for Mac OS in general; each installed additions takes up more RAM and has to be loaded into the system, taking up extra time. So only keep installed the ones you want installed.

If you have a huge scripting addition and you only want to use a small part of its functionality, you could also edit the glue and strip out portions you don't want. This is not recommended for those who don't know precisely what they are doing, and the gains may be unnoticable anyway.

GOTCHAS

  • MAKE SURE site_perl COMES FIRST IN YOUR LIBRARY PREFERENCES FOR OLD VERSIONS OF MACPERL. Thank you. :-)

  • Do NOT send an event to the MacPerl application itself and expect a reply. Instead, try $macperlglue->REPLY(0). Similarly, do not drop MacPerl onto gluemac. Instead, you can make a copy of the MacPerl application, and drop that on gluemac.

  • You should have the latest cpan-mac distribution is installed, for old versions of MacPerl.

  • You should delete old dialect glue files manually if running Mac OS 9.

TODO / BUGS

  • Specifying other attributes (transactions, etc.)

  • Add more coercions etc. to Mac::AppleEvents::Simple (feedback wanted on this, let me know what I missed)

  • Add comparison operators from glues ?

  • "tell" objects to do events

  • New AETE flags in Mac OS 8.5, Mac OS 9? Anything else new? Anything missing in backward compatibility to 7.5?

  • MacPerl (I think) needs a new idle function for waiting for replies

  • MacPerl hangs if it waits for a reply after sending an event to itself

  • Handlers (on foo ...) ?

  • Callbacks (some support exists, Cameron Ashby <cameron@evolution.com>, see Mac::AppleEvents::Simple) ?

  • Add dynamic fetching of glues?

  • Make makefile stuff work with MacPerl (5.2 and 5.6 ?)

  • More POD in modules

  • More examples (iCal, iPhoto, iTunes)

  • A real test suite (though just making sure it loads is a pretty good test :-)

  • Update glueedit

AUTHOR

Chris Nandor <pudge@pobox.com>, http://pudge.net/

Copyright (c) 1998-2005 Chris Nandor. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

THANKS

Matthias Neeracher, David Schooley, Graham Barr, John W Baxter, Marion Delgado, Eric Dobbs, Josh Gemmell, Alex Harper, Nathaniel Irons, Dave Johnson, Bart Lateur, Andy Lester, Jefferson R. Lowrey, Mat Marcus, Larry Moore, Ricardo Muggli, Vincent Nonnenmacher, Henry Penninkilampi, Peter Prymmer, Ramesh R., Axel Rose, Stephan Somogyi, Kevin Walker, Matthew Wickline, Simon Cozens, has, Bill Birkett, Lars Eggert, wren argetlahm, Ken Williams, Alan Olsen, Chris Devers, Kim Helliwell, Jelte Liebrand.

(If I left your name out, please remind me.)

SEE ALSO

Mac::AppleEvents, Mac::AppleEvents::Simple, macperlcat, Inside Macintosh: Interapplication Communication.

        http://projects.pudge.net/



Hosting generously
sponsored by Bytemark