TweetFollow Us on Twitter

March 96 - According to Script: Properties and Preferences

ACCORDING TO SCRIPT: Properties and Preferences

Cal Simone

On the way to implementing scripting support in your applications, you're bound to confront a variety of issues. In this column, I'll give you some pointers for devising and testing property names and discuss the techniques for handling preferences through scripting.

PROPERTIES

In an application's scripting vocabulary, a property is an attribute of an object. Properties can replace variables in if and repeat statements, as well as in expressions, and a script writer normally uses the AppleScript verbs set and get with them. Here I'll give some guidelines for coming up with human-language names for properties and testing the viability of those names within the overall natural style of the AppleScript language. It's important that properties have names that users can easily become familiar with. Ideally, users should be able to refer to properties in a script the way they think or speak about them.

Don't start property names with verbs. Starting property names with verbs leads to confusion when the property appears in the middle of a sentence. For example, naming a property disable call waiting leads to commands that don't read smoothly:

set disable call waiting to true 
if disable call waiting then ... 
This is somewhat clearer:
set call waiting enabled to false
if not call waiting enabled ... 
In fact, in the above case, it would be even better to name the property call waiting and use an enumeration as its value type (for a discussion of enumerations, see my article "Designing a Scripting Implementation" in develop Issue 21). The choices enabled and disabled allow grammatically correct sentences, as in the following:
set call waiting to enabled
if call waiting is disabled ... 
A little creative thinking goes a long way in making it easy for users to work with the language.

The "the" test. AppleScript allows you to add or remove the word the almost anywhere in a script without changing the meaning of the script. Many script writers precede object and property names with the word the to make their scripts easier to read. Writing your test scripts in this way helps you determine the degree to which your property names facilitate forming natural sentences.

set the service to "America Online"
if the priority is high then ...

Don't confuse attributes and actions. Sometimes setting a property can cause an immediate change on the screen. In deciding whether to use a property in this situation, a helpful rule is: When an action is initiated, use a verb; when an attribute changes (even if it produces immediate visible results), use a property. Another way of looking at this is if a visible change is immediate, it's OK to use a property, but if an action has a duration, use a verb.

As an example, the following command causes an immediate change on the screen:

set the font of the third paragraph to "Courier"
Even though setting the font property creates a visible change, the font is still an attribute of the text, not an action. On the other hand, naming a property or enumerator playing, as shown in the next two commands, is a poor choice, because playing actually initiates an action:
set playing to true   
set [the] status to playing   
The playing enumerator value in the second command is fine for obtaining state information, but a status property should be read-only. Instead of creating a property to control an action, use a verb. Verbs such as play or start playing are better suited for actions, as shown here:
play the movie "Wowie Zowie"
start playing the movie "Wowie Zowie"
Note that the commands are play and start playing, not play movie or start playing movie. In an application based on the object model, movie would be an object class.

The properties property. A properties property enables script writers to obtain all the properties for a given object in the form of a record by using a get properties construct. (I first suggested using records in this column in develop Issue 22.) The properties property can also be set with the set command. The sample properties property shown in Listing 1 can be included as a property of any object for which you allow the setting of more than one property at a time.

Listing 1. A sample properties property

{   /* array Properties: 5 elements */
   /* [5] */
   "properties",
   'Prop',
   'reco',
   "Property that allows setting of a list
      of properties.",
   reserved, singleItem, notEnumerated,
   readWrite, reserved,
   ...
},
Don't require the user to supply all the properties when setting the properties property -- allow the setting of just one or a few properties.

get the properties of the fourth paragraph 
   -- returns font, size, style, and so on
set the properties of the fourth paragraph to ~
   {font:"Helvetica", size:14} 

PREFERENCES

Developers use a variety of techniques to allow users to set preferences through scripts. I'll describe three common and easily implemented approaches for dealing with preference properties in your application class. (These same approaches can be used to implement document settings or group properties for individual objects within your application.)

Separate properties for each preference. Implementing preferences as individual properties works well when you have only a few preferences. For example:

set the connect sound to "Shriek"
set the receive folder to alias "HD:Drop Folder"
If you have many preferences, it's inefficient for the user to have to set each property individually. To solve this, you can implement your preferences as individual properties (usually in your vocabulary's application class definition) and also include a preferences property, described next.

A property that includes all the preferences. You can make a single preferences or settings property, which is a record that's defined elsewhere in your vocabulary. To define the elements of the record, create a fake "class" in your vocabulary, preferably in your Type Definitions Suite, to serve as the definition of the element labels in a record definition. In the comment field for your "class," be sure to document clearly that this is a record definition, not an object class. Listing 2 illustrates this technique; for more information, see the section "Define Record Labels in a Record Definition" in "Designing a Scripting Implementation" in develop Issue 21.

Listing 2. A sample preferences property

/* First, define this application property. */
{   /* array Properties: 5 elements */
   /* [5] */
   "preferences",
   'Pref',   
   'cprf,      /* for "preferences class" */
   "Property that allows setting some or all
      of your preferences.",
   reserved, singleItem, notEnumerated,
   readWrite, reserved,
   ...      /* more reserved items */
},
... /* more property definitions */

/* Later, in your Type Definitions Suite, */
/* create a fake class. */
{   /* array Classes: 1 element */
/* [1] */
"preferences record",
'cprf',
"A record containing individual preferences",
{   /* array Properties: 10 elements */
   /* [1] */
   "connect sound", 'CSND', 'itxt',
   "the name of the sound to use when
      connected",
   reserved, singleItem, notEnumerated,
   ...
   /* [2] */
   "receive folder", 'RFLD', 'alis',
   "the folder to place files when received",
   reserved, singleItem, notEnumerated,
   ...
},
{   /* array Elements: 0 elements */
}
Lists and records are the two principal constructs in AppleScript that don't lend themselves to human sentence structure. They are, however, an integral part of the language and can occasionally help to make the script writer's life easier. When you use a record to create a preferences property, it's OK to stray a little from strict natural-language style. Of course, when referring to elements of a list or record, you should use natural-language style.

As with the properties property described earlier, don't require the user to set all the individual preferences at once. Allow the setting of just one or a few preferences at a time:

set the preferences to ~
   {connect sound:"Shriek", ~
    receive folder:alias "HD:Drop folder"}
A user can address individual preferences as if they were defined as separate application properties. To allow for varying user experience with AppleScript, your application should always accept property specifications for individual preferences using the technique described above, regardless of whether the user includes the qualifying phrase of the preferences. For example, both of the following statements should be allowed:
set the receive folder of the preferences to ~
   alias "HD:Drop Folder"
set the receive folder to alias "HD:Drop Folder"

Multiple "group" properties for grouping preferences. If you have many preferences or want to group the preferences according to similar functionality, such as those often found in multipaneled dialog boxes, you can create separate properties for groups of preferences or settings (using the record definition technique just described). The properties can reflect the groupings you've set up in your graphical interface:

set the compiler preferences to ~
   {warnings included:true, ~
   default integer size:short integer}

set the drawing settings to ~
   {pen size:{1,2}, shape:circle}
A user addresses an individual preference by including in the object property specification the record that the preference is an element of, as follows:
the pen size of the drawing settings
set the shape of the drawing settings to ~
   rectangle
set the default integer size of the compiler ~
   preferences to short integer

PARTING WORDS

Following these guidelines in implementing scriptability in your applications makes it easier for users to write scripts. Although they may seem like small points, it's the details that mean the difference between frustration and smooth sailing for the script writer. Remember to think about the way a user would write or speak about accomplishing what they want to do. Until next time, I remain your obedient servant on the AppleScript front. I'll see you on applescript-implementors@abs.apple.com, the mailing list for scriptability.

CAL SIMONE (AppleLink MAIN.EVENT, Internet mainevent@his.com) wants your dictionary for the Webster database, which will be used to help resolve human-name conflicts between different applications and scripting additions. He'll be analyzing the terms in your vocabulary against others in search of similarities and differences. Send your 'aete' resources to Cal via AppleLink or the Internet.*

Thanks to Eric Gundrum, Jon Pugh, and Derrick Schneider for reviewing this column.*

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Cyberduck 4.7.1 - FTP and SFTP browser....
Cyberduck is a robust FTP/FTP-TLS/SFTP browser for the Mac whose lack of visual clutter and cleverly intuitive features make it easy to use. Support for external editors and system technologies such... Read more
PDFpen 7.2 - Edit and annotate PDFs with...
We're also offering PDFpenPro for 30% off! PDFpen allows users to easily edit PDF's. Add text, images and signatures. Fill out PDF forms. Merge or split PDF documents. Reorder and delete pages. Even... Read more
Skype 7.9.746 - Voice-over-internet phon...
Skype allows you to talk to friends, family and co-workers across the Internet without the inconvenience of long distance telephone charges. Using peer-to-peer data transmission technology, Skype... Read more
Apple GarageBand 10.1 - Complete recordi...
The new GarageBand is a whole music creation studio right inside your Mac -- complete with keyboard, synths, orchestral and percussion instruments, presets for guitar and voice, an entirely... Read more
Duplicate Annihilator 5.7.7 - Find and d...
Duplicate Annihilator takes on the time-consuming task of comparing the images in your iPhoto library using effective algorithms to make sure that no duplicate escapes. Duplicate Annihilator... Read more
OS X Server 4.1.3 - For OS X 10.10 Yosem...
Designed for OS X and iOS devices, OS X Server makes it easy to share files, schedule meetings, synchronize contacts, develop software, host your own website, publish wikis, configure Mac, iPhone,... Read more
Firefox 39.0 - Fast, safe Web browser. (...
Firefox offers a fast, safe Web browsing experience. Browse quickly, securely, and effortlessly. With its industry-leading features, Firefox is the choice of Web development professionals and casual... Read more
pwSafe 4.1 - Secure password management...
pwSafe provides simple and secure password management across devices and computers. pwSafe uses iCloud to keep your password databases backed-up and synced between Macs and iOS devices. It is... Read more
Kodi 15.0.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
Coda 2.5.11 - One-window Web development...
Coda is a powerful Web editor that puts everything in one place. An editor. Terminal. CSS. Files. With Coda 2, we went beyond expectations. With loads of new, much-requested features, a few surprises... Read more

This Week at 148Apps: June 29-July 3, 20...
Into 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 above the... | Read more »
Sonic Runners Guide
Despite its flaws, Sonic Runners' platforming action is actually quite fun. Though it can be a little more complicated than old-school Sonic games. Here's how to make sure you're up to speed when jumping in. [Read more] | Read more »
Rage of Bahamut is Giving Almost All of...
The App Store isn't what it used to be back in 2012, so it's not unexpected to see some games changing their structures with the times. Now we can add Rage of Bahamut to that list with the recent announcement that the game is severely cutting back... | Read more »
Adventures of Pip (Games)
Adventures of Pip 1.0 Device: iOS iPhone Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: ** ONE WEEK ONLY — 66% OFF! *** “Adventures of Pip is a delightful little platformer full of charm, challenge and impeccable... | Read more »
Divide By Sheep - Tips, Tricks, and Stre...
Who would have thought splitting up sheep could be so involved? Anyone who’s played Divide by Sheep, that’s who! While we’re not about to give you complete solutions to everything (because that’s just cheating), we will happily give you some... | Read more »
NaturalMotion and Zynga Have Started Tea...
An official sequel to 2012's CSR Racing is officially on the way, with Zynga and NaturalMotion releasing a short teaser trailer to get everyone excited. Well, as excited as one can get from a trailer with no gameplay footage, anyway. [Read more] | Read more »
Grab a Friend and Pick up Overkill 3, Be...
Overkill 3 is a pretty enjoyable third-person shooter that was sort of begging for some online multiplayer. Fortunately the begging can stop, because its newest update has added an online co-op mode. [Read more] | Read more »
Scanner Pro's Newest Update Adds Au...
Scanner Pro is one of the most popular document scanning apps on iOS, thanks in no small part to its near-constant updates, I'm sure. Now we're up to update number six, and it adds some pretty handy new features. [Read more] | Read more »
Heroki (Games)
Heroki 1.0 Device: iOS Universal Category: Games Price: $7.99, Version: 1.0 (iTunes) Description: CLEAR THE SKIES FOR A NEW HERO!The peaceful sky village of Levantia is in danger! The dastardly Dr. N. Forchin and his accomplice,... | Read more »
Wars of the Roses (Games)
Wars of the Roses 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: | Read more »

Price Scanner via MacPrices.net

Apple refurbished Mac minis available startin...
The Apple Store has Apple Certified Refurbished 2014 Mac minis available starting at $419. Apple’s one-year warranty is included with each mini, and shipping is free: - 1.4GHz Mac mini: $419 $80 off... Read more
College Student Deals: Additional $100 off Ma...
Take an additional $100 off all MacBooks and iMacs at Best Buy Online with their College Students Deals Savings, valid through August 8, 2015. Anyone with a valid .EDU email address can take... Read more
Sky Atlas Star Walk 2 App For iPhone And iPa...
Vito Technology, developer of educational apps for Android and iOS, is for a limited time offering free of charge their Star Walk 2, the next generation of the company’s best-selling stargazing guide... Read more
13-inch 1.6GHz MacBook Air on sale for $849,...
Amazon has the 2015 13″ 1.6GHz/128GB MacBook Air on sale for $849.99 including free shipping. Their price is $150 off MSRP, and it’s the lowest price available for this model. Read more
13-inch 2.5GHz MacBook Pro on sale for $999,...
Adorama has the 13-inch 2.5GHz MacBook Pro on sale for $999 including free shipping plus NY & NJ sales tax only. Their price is $100 off MSRP. 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
15-inch Retina MacBook Pros on sale for up to...
B&H Photo has new 2015 15″ Retina MacBook Pros on sale for up to $225 off MSRP including free shipping plus NY sales tax only: - 15″ 2.2GHz Retina MacBook Pro: $1819 $180 off - 15″ 2.5GHz Retina... Read more
RamDisk4Mac App Helps Run Your Mac Faster And...
Ever use a RAM disk? If you’ve come to the Mac in the OS X era, likely not. The Classic Mac OS had a RAM disk function built-in, but that was dropped in the conversion to OS X. What is a RAM disk?... Read more
13-inch 1.6GHz MacBook Air on sale for $849,...
Best Buy has the 2015 13″ 1.6GHz/128GB MacBook Air on sale for $849.99 on their online store this weekend. Choose free shipping or free local store pickup (if available). Sale price for online orders... Read more
Apple Refurbished iMacs available for up to $...
The Apple Store has Apple Certified Refurbished iMacs available for up to $380 off the cost of new models. Apple’s one-year warranty is standard, and shipping is free: - 27″ 3.5GHz 5K iMac – $1949 $... 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
Senior Payments Security Manager - *Apple*...
**Job Summary** Apple , Inc. is looking for a highly motivated, innovative and hands-on senior payments security manager to join the Apple Pay security team. You will Read more
Sr. Technical Services Consultant, *Apple*...
**Job Summary** Apple Professional Services (APS) has an opening for a senior technical position that contributes to Apple 's efforts for strategic and transactional Read more
Sr. Payment Program Manager, *Apple* Pay -...
**Job Summary** Apple Pay is an exciting environment and a…devices in a simple, private and secure way. The Apple Pay Team is looking for an experienced Senior Read more
Project Manager - *Apple* Pay Security - Ap...
**Job Summary** The Apple Pay Security team is seeking a highly organized, results-driven Project Manager to drive the development of Apple Pay Security. If you are Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.