TweetFollow Us on Twitter

AppleScript Code Libraries

Volume Number: 22 (2006)
Issue Number: 12
Column Tag: AppleScript Essentials

AppleScript Code Libraries

by Benjamin S. Waldie

If you have been reading my columns for a while (prior to my introductory series on scripting different applications), then you may know that I am somewhat of a subroutine handler fanatic. I feel that handlers are an extremely important part of AppleScript development, and that every AppleScripter should be using them quite often. Unfortunately, many AppleScript developers do not.

There are many benefits to using handlers in a script. Let's discuss a few of these briefly. Handlers provide a mechanism for modularizing AppleScript code into generic chunks, which can be called from multiple locations within a script. This can lead to more efficient script writing. Instead of spending time writing virtually the same code over and over again throughout a script, you can instead focus more time on writing a solid and reliable handler, which can be called numerous times throughout the script. Not only does this help to cut down on the total amount of code you need to write in a script, but it also helps to provide a more focused completed script. Because multiple sections of the script call the same handler code, there are typically fewer areas to troubleshoot if problems do occur during execution. Furthermore, if written modularly enough, it may even be possible to extract a handler from a script, and plug it into other scripts, potentially reducing script writing time in the future too. This leads me into the main focus of this month's column, AppleScript code libraries.

What is an AppleScript Code Library

What exactly is an AppleScript code library? An AppleScript code library, aka a script library, is an AppleScript file that contains pieces of code, usually handlers, which may be loaded and accessed by another script during its execution. AppleScript code libraries provide an excellent way to organize generic chunks of code, to be called by one or more scripts.

For example, suppose you often write scripts that automate tasks in QuarkXPress. The odds are probably pretty good that many of these scripts will perform similar tasks, and many may use similar or identical code. If this were the case, it would make sense to write much of your Quark code as generic handlers, which can then be merged together into a single script file to form a script library. This library of Quark handlers could then be saved into a central location, and then loaded by other scripts in the future, which can then call its handlers as needed.

Building a Script Library

Building a script library is really as straightforward as creating any AppleScript file. There aren't really any hardcore requirements. A script library will often contain handlers, but it doesn't need to. It can contain any thing that any other script can contain, including properties, globals, a run handler, etc. A script library can even load other script libraries.

Preparing to Follow Along

The example code that we will explore throughout this month's column will involve calling code within a script library file. To follow along with these examples, you'll need to create a script library file. Begin by creating a new Script Editor document, and entering the following code.

property someProperty : "Property Value"
display dialog "Running..."
on someHandler()
   display dialog "Handler executing..."
end someHandler
on displayProperty()
   display dialog someProperty
end displayProperty

As you can see, this code that will make up our script library contains a property, some run handler code, and some subroutine handlers. We will walk through the process of accessing each of these elements in our script library from within another script.

Next, we need to save our script library. To do this, just save the Script Editor document as a compiled script to your desktop, and name it My Library.scpt.

Loading a Script Library

Now that we have created our script library, we are ready to begin accessing it from another script. To do this, we will make use of a command that is included in the Scripting Commands suite of the Standard Additions scripting addition, called load script. The load script command accepts one direct parameter, a reference to a script file to be loaded. For example:

set theLibraryPath to alias ((path to desktop folder as string) & "My Library.scpt")
load script theLibraryPath
--> "script"

If you run the above example code, you will find that, in Script Editor's result pane, the result of the load script command is a reference to the newly loaded script library. Like any other result, this reference may be placed into a variable, for later reference throughout your script. For example:

set theLoadedScript to load script theLibraryPath

Types of Scripts that May Be Loaded

Momentarily, we will explore what you can do once you have loaded a script library file. However, I first want to mention the types of script library files that may be loaded. The load script command may be used to load compiled script files, script applications, script bundles, and script application bundles. It may not be used to load scripts that have been saved in text format. Also, if you are using an older version of Mac OS X (pre-10.3.x), then you will not be able to load script bundles or script application bundles. The ability to load these types of scripts was not possible prior to AppleScript version 1.9.2 in Mac OS X 10.3.

Running a Script Library

So, now that we have loaded a script library file, what do we do with it? One thing that we can do with it is run it. This can be done by simply telling the loaded script to run. For example:

set theLibraryPath to alias ((path to desktop folder as string) & "My Library.scpt")
set theLoadedScript to load script theLibraryPath
tell theLoadedScript to run
--> {button returned:"OK"}

If you test this example code, then you will find that telling the loaded script to run will result in the execution of any code located within the loaded script's run handler. See figure 1.



Figure 1. Running a Loaded Script Library

You will also find that, if the run handler of the loaded script produces a result, then that result will be passed back to the loading script as the result of the run command.

There are actually several syntactical variations to running a loaded script. Another way is to use the run command, followed by a reference to the loaded script as a direct parameter. For example:

run theLoadedScript

Yet another way to run a loaded script is to make use of the run script command, which is also found in the Scripting Commands suite in the Standard Additions scripting addition. This command is also followed by a reference to the loaded script as its direct parameter.

run script theLoadedScript

When using the run script command, it's also not actually necessary to load the script prior to running it. The run script command itself may be passed the path to a script file as its direct parameter. This will cause the script file to be loaded and run, all in one shot, as demonstrated here:

run script theLibraryPath

Calling Handlers within a Script Library

While running a loaded script is great, and can sometimes be very useful, the real power comes with the ability to trigger handlers within loaded script libraries. Once a script has been loaded, any of its handlers are at your disposal, and may be called as needed, throughout the loading script.

Handlers in a loaded script are called much in the same way that local handlers are called within a script. Unlike local handlers, however, they must just be directed to the loaded script. Often, this is done through the use of a simple tell statement. In other words, the loading script tells the loaded script to execute a specific handler. For example:

set theLibraryPath to alias ((path to desktop folder as string) & "My Library.scpt")
set theLoadedScript to load script theLibraryPath
tell theLoadedScript to someHandler()
--> {button returned:"OK"}

If you run the previous example code, you will find that the someHandler() handler within the loaded script is executed, as indicated by the dialog the handler displays. See figure 2.



Figure 2. Calling a Handler in a Loaded Script Library

As an alternative to using a tell statement to call a handler within a loaded script, another equally acceptable method is the following, which will perform in exactly the same manner as the previous example.

someHandler() of theLoadedScript

Accessing Properties within a Script Library

Referencing Properties in a Script Library

As one might expect, if a loaded script contains properties, then those properties may be accessed by any code, such as handlers, within the loaded script. For example, here is some example code that will execute a handler within our loaded script. This handler will display the value of a property in the loaded script. See figure 3.

set theLibraryPath to alias ((path to desktop folder as string) & "My Library.scpt")
set theLoadedScript to load script theLibraryPath
tell theLoadedScript to displayProperty()



Figure 3. Calling a Handler in a Loaded Script, to Display a Property Value

Properties within a loaded script may also be accessed by the loading script. This is done similarly to the process of calling handlers in a loaded script from within the loading script. For example:

set theLibraryPath to alias ((path to desktop folder as string) & "My Library.scpt")
set theLoadedScript to load script theLibraryPath
someProperty of theLoadedScript
--> "Property Value"

Modifying Properties in a Script Library

As you may know, when utilized in a script application, properties are persistent between executions of the script. In other words, if you modify the value of a property within a script application, then the modified property value will be retained until the property is modified again, or until the script is recompiled. Upon a recompile, the property will revert to its original value.

Properties in loaded scripts are handled slightly differently. If you modify a property in a loaded script, the modified property value will be retained as long as the script remains loaded. However, the next time the script is loaded, it will revert back to its original value. The modified property value is not retained between loads. This can be demonstrated via the following example code.

set theLibraryPath to alias ((path to desktop folder as string) & "My Library.scpt")
set theLoadedScript to load script theLibraryPath
tell theLoadedScript to displayProperty()
set someProperty of theLoadedScript to "New Property Value"
tell theLoadedScript to displayProperty()

If you run the example code above, you will find that the displayProperty() handler will be called twice. Once, immediately after the script has been loaded, and again, after the value of the property someProperty has been modified to a new value. The first time the displayProperty() handler is called, it will display a dialog indicating the property's original value, shown previously in figure 3. The second time the handler is called, it will display a dialog indicating the property's new value, showing that the property's value has actually been changed. See figure 4.



Figure 4. Calling a Handler in a Loaded Script, to Display a Modified Property Value

Now, to demonstrate that the modified property value is not retained between loads, try running the previous example code a second time. When you do this, you will find that the first time the displayProperty() handler is called, it displays the original unmodified value for property someProperty.

Storing a Modified Script Library

However, it is actually possible to retain a modified property value within a loaded script. To do this, the loaded script must be stored back into itself after the property has been modified. This is done using the store script command, which is found in the Scripting Commands suite in the Standard Additions scripting addition. For example:

set theLibraryPath to alias ((path to desktop folder as string) & "My Library.scpt")
set theLoadedScript to load script theLibraryPath
tell theLoadedScript to displayProperty()
set someProperty of theLoadedScript to "New Property Value"
store script theLoadedScript

In the example code above, notice that, while we have specified the loaded script to be stored, we have not specified where it should be stored. When the store script command is used with only a direct parameter, the script to be stored, you will be prompted to specify where the loaded script is to be stored. See figure 5.



Figure 5. Storing a Script Using a Specified Name and Location

To store the script back to its original file path, we can specify a file path for the store script command's optional in labeled parameter. For example:

store script theLoadedScript in theLibraryPath

When used in this manner to store a script back to its original path, the store script command will attempt to overwrite the existing script file. Because of this, another dialog will be displayed, asking whether the existing file should be replaced. See figure 6.



Figure 6. Storing a Script With or Without Replacing an Existing Script

To allow the loaded script to be stored back to its original path without displaying this dialog, we can make use of another optional labeled parameter for the store script command, replacing. For example:

store script theLoadedScript in theLibraryPath with replacing

Running this example code will now result in our loaded script being stored back to its original path, with no dialog being displayed. If you now load the script again and call the displayProperty() handler, you will find that the new property value has been retained. The modified property value will continue to be retained until it is modified again, or until the script library file is opened and recompiled.

In Closing

Hopefully, you're starting to see the benefits of using script libraries, especially for sharing subroutine handlers among multiple scripts. The example code throughout this column should provide you with a good foundation for starting to create and access your own libraries. Once you feel comfortable using the techniques that we have discussed, you may want to consider exploring some other interesting ways of utilizing script libraries.

Try saving a script library as a stay opened application and pre-launching it to reduce loading time. Then, allow multiple scripts to call the code within the running script library. Also, we've discussed accessing properties in loaded scripts. For extra credit, try also exploring how globals work in loaded libraries. Can globals be shared between the loading script and the loaded script? Perform some tests on your own to find out.

Until next time, keep scripting!


Ben Waldie is the author of the best selling books "AppleScripting the Finder" and the "Mac OS X Technology Guide to Automator", available from <http://www.spiderworks.com>, as well as an AppleScript Training CD, available from <http://www.vtc.com>. Ben is also president of Automated Workflows, LLC, a company specializing in AppleScript and workflow automation consulting. For years, Ben has developed professional AppleScript-based solutions for businesses including Adobe, Apple, NASA, PC World, and TV Guide. For more information about Ben, please visit <http://www.automatedworkflows.com>, or email Ben at <ben@automatedworkflows.com>.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

BBEdit 11.1.1 - Powerful text and HTML e...
BBEdit is the leading professional HTML and text editor for the Mac. Specifically crafted in response to the needs of Web authors and software developers, this award-winning product provides a... Read more
CrossOver 14.1.3 - Run Windows apps on y...
CrossOver can get your Windows productivity applications and PC games up and running on your Mac quickly and easily. CrossOver runs the Windows software that you need on Mac at home, in the office,... Read more
Little Snitch 3.5.3 - Alerts you about o...
Little Snitch gives you control over your private outgoing data. Track background activity As soon as your computer connects to the Internet, applications often have permission to send any... Read more
OmniGraffle Pro 6.2.3 - Create diagrams,...
OmniGraffle Pro helps you draw beautiful diagrams, family trees, flow charts, org charts, layouts, and (mathematically speaking) any other directed or non-directed graphs. We've had people use... Read more
OmniFocus 2.2 - GTD task manager with iO...
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
Cocktail 8.4 - General maintenance and o...
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
PDFKey Pro 4.3 - Edit and print password...
PDFKey Pro can unlock PDF documents protected for printing and copying when you've forgotten your password. It can now also protect your PDF files with a password to prevent unauthorized access and/... Read more
Kodi 15.0.beta1 - Powerful media center...
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
DiskCatalogMaker 6.4.12 - Catalog your d...
DiskCatalogMaker is a simple disk management tool which catalogs disks. Simple, light-weight, and fast. Finder-like intuitive look and feel. Super-fast search algorithm. Can compress catalog data... Read more
Macs Fan Control 1.3.0.0 - Monitor and c...
Macs Fan Control allows you to monitor and control almost any aspect of your computer's fans, with support for controlling fan speed, temperature sensors pane, menu-bar icon, and autostart with... Read more

Moleskine Timepage – Calendar for iCloud...
Moleskine Timepage – Calendar for iCloud, Google & Exchange 1.0 Device: iOS iPhone Category: Productivity Price: $4.99, Version: 1.0 (iTunes) Description: The most elegant calendar for your pocket and wrist, Timepage is a... | Read more »
QuizUp Gets Social in its New Update
Plain Vanilla Corp has released a new and improved version of their popular trivia game, QuizUp. The app now emphasizes social play so you can challenge friends from all over the world. [Read more] | Read more »
The Deep (Games)
The Deep 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: Swipe Controls Delve into the deep in this retro rogue-like! Swipe to move your diver around and keep away from the enemies as you... | Read more »
Battle of Gods: Ascension (Games)
Battle of Gods: Ascension 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: TURN-BASED TACTICAL COMBATFight tactical battles against the forces of Hades! In Battle of Gods: Ascension you play... | Read more »
Shadowmatic's Latest Update Adds a...
Shadowmatic's shadowy shadow-ness is getting a little shadowy-er thanks to a recent update that adds an Arcade Mode. [Read more] | Read more »
Sunrise Calendar and Slack Have Assimila...
Wunderlist is perhaps one of the most populat and beloved productivity apps on the App Store - and now it's gone and incorporated itself into other useful services like Sunrise Calendar and Slack. [Read more] | Read more »
Crossy Road Devs Hipster Whale are Bring...
Hipster Whale, the minds behind the rather popular (and rather great) Crossy Road, have teamed-up with Bandai Namco to create PAC-MAN 256: an absolutely bonkers looking maze runner chaser thing. | Read more »
Meet the New Spotify Music
Spotify Music  has a lot going on. They're introducing 3 new modes to serve all your musical needs, with the "Now" start page  gives you curated playlists based on your particular tastes. As you listen the app will learn more about your tastes and... | Read more »
What the Apple Watch Gets Right, and Wha...
| Read more »
Celebrate PAC-MAN's 35th Birthday W...
BANDAI NAMCO Entertainment America is celebrating PAC-MAN's 35th anniversary by releasing updates for PAC-MAN and PAC-MAN Lite for iOS. [Read more] | Read more »

Price Scanner via MacPrices.net

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
What Would the ideal Apple Productivity Platf...
For the past four years I’ve kept a foot in both the Mac and iPad camps respectively. my daily computing hours divided about 50/50 between the two devices with remarkable consistency. However, there’... Read more
PageMeUp 1.2.1 Ten Dollar Page Layout Applica...
Paris, France-based Softobe, an OS X software development company, has announced that their PageMeUp v. 1.2.1, is available on the Mac App Store for $9.99. The license can be installed on up to 5... Read more
Eight New Products For USB Type-C Application...
Fresco Logic, specialists in advanced connectivity technologies and ICs, has introduced two new product families targeting the Type-C connector recently introduced across a number of consumer... Read more
Scripps National Spelling Bee Launches Buzzwo...
Scripps National Spelling Bee fans can monitor the action at the 2015 Spelling Bee with the new Buzzworthy app for iOS, Android and Windows mobile devices. The free Buzzworthy app provides friendly... Read more
13-inch 2.5GHz MacBook Pro on sale for $120 o...
B&H Photo has the 13″ 2.5GHz MacBook Pro on sale for $979 including free shipping plus NY sales tax only. Their price is $120 off MSRP, and it’s the lowest price for this model (except for Apple’... Read more
27-inch 3.3GHz 5K iMac on sale for $1899, $10...
B&H Photo has the new 27″ 3.3GHz 5K iMac on sale for $1899.99 including free shipping plus NY tax only. Their price is $100 off MSRP. Read more
Save up to $50 on iPad Air 2, NY tax only, fr...
B&H Photo has iPad Air 2s on sale for up to $50 off MSRP including free shipping plus NY sales tax only: - 16GB iPad Air 2 WiFi: $469 $30 off - 64GB iPad Air 2 WiFi: $549.99 $50 off - 128GB iPad... Read more
Updated Mac Price Trackers
We’ve updated our Mac Price Trackers with the latest information on prices, bundles, and availability on systems from Apple’s authorized internet/catalog resellers: - 15″ MacBook Pros - 13″ MacBook... Read more
New 13-inch 2.9GHz Retina MacBook Pro on sale...
B&H Photo has the 13″ 2.9GHz/512GB Retina MacBook Pro on sale for $1699.99 including free shipping plus NY tax only. Their price is $100 off MSRP, and it’s the lowest price for this model from... 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* Watch SW Application Project Manager...
**Job Summary** The Apple Watch software team is looking for an Application Engineering Project Manager to work on new projects for Apple . The successful candidate Read more
Engineering Manager for *Apple* Maps on the...
…the Maps App Team get to take part in just about any new feature in Apple Maps, often contributing a majority of the feature work. In our day-to-day engineering work, we Read more
Senior Software Engineer - *Apple* SIM - Ap...
Changing the world is all in a day039s work at Apple . If you love innovation, here039s your chance to make a career of it. You039ll work hard. But the job comes with Read more
Lead *Apple* Solutions Consultant - Retail...
**Job Summary** Job Summary The Lead ASC is an Apple employee who serves as the Apple business manager and influencer in a hyper-business critical Reseller's store Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.