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

Monolingual 1.6.4 - Remove unwanted OS X...
Monolingual is a program for removing unnecesary language resources from OS X, in order to reclaim several hundred megabytes of disk space. If you use your computer in only one (human) language, you... Read more
CleanApp 5.0 - Application deinstaller a...
CleanApp is an application deinstaller and archiver.... Your hard drive gets fuller day by day, but do you know why? CleanApp 5 provides you with insights how to reclaim disk space. There are... Read more
Fantastical 2.0 - Create calendar events...
Fantastical is the Mac calendar you'll actually enjoy using. Creating an event with Fantastical is quick, easy, and fun: Open Fantastical with a single click or keystroke Type in your event details... Read more
Cocktail 8.2 - 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
Direct Mail 4.0.4 - Create and send grea...
Direct Mail is an easy-to-use, fully-featured email marketing app purpose-built for OS X. It lets you create and send great looking email campaigns. Start your newsletter by selecting from a gallery... Read more
jAlbum Pro 12.6 - Organize your digital...
jAlbum Pro has all the features you love in jAlbum, but comes with a commercial license. With jAlbum, you can create gorgeous custom photo galleries for the Web without writing a line of code!... Read more
jAlbum 12.6 - Create custom photo galler...
With jAlbum, you can create gorgeous custom photo galleries for the Web without writing a line of code! Beginner-friendly, with pro results Simply drag and drop photos into groups, choose a design... Read more
Lyn 1.5.9 - Lightweight image browser an...
Lyn is a lightweight and fast image browser and viewer designed for photographers, graphic artists and Web designers. Featuring an extremely versatile and aesthetically pleasing interface, it... Read more
Sublime Text 3080 - Sophisticated text e...
Sublime Text is a sophisticated text editor for code, markup, and prose. You'll love the slick user interface, extraordinary features, and amazing performance. Goto Anything. Use Goto Anything to... Read more
WALTR 1.0.11 - Drag-and-drop any media f...
WALTR is designed to make it easy to upload and convert any music or video file to an iPad or iPhone format for native playback. It supports a huge variety of media file types, including MP3, MP4,... Read more

Bio Inc's New Expansion is Infectin...
Bio Inc., by DryGin Studios, is the real time strategy game where you infect a human body with the worst virus your evil brain can design. Recently, the game was updated to add a whole lot of new features. Now you can play the new “Lethal”... | Read more »
The Monocular Minion is Here! Despicable...
Despicable Me: Minion Rush, by Gameloft, is introducing a new runner to the mix in their latest update. Now you can play as Carl, the prankster minion. Carl has a few new abilities to play with, including running at a higher speed from the start.... | Read more »
Dungeon of Madness (Games)
Dungeon of Madness 1.0.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0.0 (iTunes) Description: Dungeon of Madness is an action game where you rotate tiles to create our own route. Help the hero by connecting the... | Read more »
Filters for iPhone (Photography)
Filters for iPhone 1.0 Device: iOS iPhone Category: Photography Price: $.99, Version: 1.0 (iTunes) Description: | Read more »
Jump'N'Shoot Attack (Games)
Jump'N'Shoot Attack 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: A mobile game for gamers! Join Louise Lightfoot, the legendary "Master of Jumping and Shooting", on her mission to save... | Read more »
Space Bounties Inc. (Games)
Space Bounties Inc. 1.4 Device: iOS Universal Category: Games Price: $1.99, Version: 1.4 (iTunes) Description: SuperGameDroid: 4/5 "Satisfying futuristic RPG combat, high replay value, and a heavy dose of nostalgia make Space... | Read more »
Gamebook: Pocket RPG (Games)
Gamebook: Pocket RPG 1.0.11 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0.11 (iTunes) Description: Walk into the Land of Lanthir Lamath ruled by wicked skeletons and fight for your life in a thrilling adventure.... | Read more »
Kids Can Mix, Match, and Catch with Tata...
Tatadada MixMatch, by Tatadada Ltd, is a mobile version of the classic game of mix & match. The game uses brightly colored creatures to train your children's pattern matching skills and hand-eye coordination. It's aimed at children around age 5... | Read more »
The Trace: Murder Mystery Game (Games)
The Trace: Murder Mystery Game 1.2.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.2.0 (iTunes) Description: | Read more »
This Week at 148Apps: March 16-20, 2015
Spring Roars In At 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... | Read more »

Price Scanner via MacPrices.net

Logitech Says MX Master Is Its Most Advanced...
Logitech’s new MX Master Wireless Mouse incorporates the best of Logitech’s many computer mouse innovations into a striking hand-sculpted design. The company claims that the MX Master creates a new... Read more
Save up to $300 on a new Mac, $30 on an iPad,...
Purchase a new Mac or iPad at The Apple Store for Education and take up to $300 off MSRP. All teachers, students, and staff of any educational institution qualify for the discount. Shipping is free,... Read more
Apple refurbished 2014 MacBook Airs available...
The Apple Store lowered prices on Apple Certified Refurbished 2014 MacBook Airs recently, with models now available starting at $679. An Apple one-year warranty is included with each MacBook, and... Read more
Mac Notebook Evolution; A Desktop Replacement...
More often than not right from the beginning, Apple’s Macs have tended to skew toward small. The original Macs were called “compacts,”, and notwithstanding a few exceptions like the honking Big Mac... Read more
13-inch 1.4GHz/128GB MacBook Air (Apple refur...
The Apple Store has Apple Certified Refurbished 2014 13″ 1.4GHz/128GB MacBook Airs available for $759 including free shipping plus Apple’s standard one-year warranty. Their price is $240 off original... Read more
YEP! Alternative Browser for iOS Now Supports...
Pfaeffikon, Switzerland based Power App AG has announced the release of an update to their Yep! Web Browser (v1.3.0) for iOS8 iPhone and iPad. Yep! hit the App Store shortly after the release of iOS... Read more
15-inch Retina MacBook Pros on sale for up to...
B&H Photo has the new 2014 15″ Retina MacBook Pros on sale for up to $250 off MSRP for a limited time. Shipping is free, and B&H charges NY sales tax only: - 15″ 2.2GHz Retina MacBook Pro: $... Read more
Clearance 13-inch Retina MacBook Pros availab...
B&H Photo has leftover 2014 13″ Retina MacBook Pros on sale for up to $250 off original MSRP. Shipping is free, and B&H charges NY sales tax only: - 13″ 2.6GHz/128GB Retina MacBook Pro: $1098... Read more
Clearance 2014 MacBook Airs on sale for up to...
B&H Photo has MacBook Airs on sale for up to $180 off original MSRP. Shipping is free, and B&H charges NY sales tax only: - 11″ 128GB MacBook Air: $789.99 110 off original MSRP - 11″ 256GB... Read more
Apple refurbished Time Capsules available for...
The Apple Store has certified refurbished Time Capsules available for $100 off MSRP. Apple’s one-year warranty is included with each Time Capsule, and shipping is free: - 2TB Time Capsule: $199, $100... Read more

Jobs Board

*Apple* Retail - Multiple Positions (US) - D...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
*Apple* Systems Engineer - Pre Sales, Educat...
…is responsible for proactively providing technical expertise to drive sales of Apple solutions into assigned accounts. The SE architects, validates, and assists in 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
*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* 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
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.