TweetFollow Us on Twitter



Scripting Quandaries


[IMAGE 081-082_According_to_Scri1.GIF]

The world of scripting is heating up. More and more developers are getting hip to scriptability, but they're discovering it's not a simple matter -- implementing scripting support in an application involves many complex issues. That's where this column comes in.

My article, "Designing a Scripting Implementation," in the last issue ofdevelop (Issue 21) offered approaches you'll want to consider when designing your scripting implementation (your object model hierarchy and your human vocabulary), as well as some basic tips and guidelines for making your application scriptable. This column picks up where that article left off, elaborating on many of the same issues and providing further tips, tricks, and standards for scriptability. In this first installment of the column, I'll clarify a couple of points that some developers found confusing in the article; then I'll give some new guidelines.

In my previous article, I suggested that one place to start your scripting implementation is to implement your menu commands. Permit me to clarify. Looking at menu commands is useful because they can suggest functionality that users should be able to script. But to maintain consistency with other object model-based applications, you shouldnot implement scripting commands that simply mimic the menu commands.

Resist the temptation to fill up your dictionary with all your menu items, even though it might be easier to write your event handlers this way. Instead, implement the object model (discussed at length in "Apple Event Objects and You" in develop Issue 10 and "Better Apple Event Coding Through Objects" in Issue 12). Keep the number of verbs small, implement standard verbs wherever applicable, and let the script writer apply those verbs (especially make, get, and set) to a large number of objects.

I mentioned in the last issue that you should begin all the terms in your dictionary (except for proper names) with lowercase letters. This applies not only to object names but to verbs as well. There are two reasons for this rule. First, AppleScript allows commands to be embedded within commands (particularly when the embedded command is from a scripting addition such aschoose file), and these complex command statements read better when all the verbs are in lowercase. For example:

set myFile to choose file with prompt "Pick it!"

Second, if you were to include an entire suite (such as the Required or Core suite) from the system dictionary and then add your own verbs starting with uppercase, you'd end up having a mixture of verbs beginning withuppercase and those beginning with lowercase displayedin your dictionary, not a pretty picture.

Developers are sometimes confused about how to handle a request from an Apple event or a script to get an object. In the early days, especially when programs were communicating directly with other programs, developers thought that getting an object meant returning the internal data structure of the object, such as a WindowRecord or other C structure. In today's scripting world, you should never return raw internal data structures. What you should return depends on the object or property requested.

Applications, windows, documents, and interface elements. In most cases, when the object requested is an application, a window, a document, or an interface element (such as a button), you should return an error since you can't really bring these types of objects into your script. For example, get window 1 should result in an error. One exception is that if your application is a script-controlled interface builder, you might want to return references to the windows, documents, and interface elements.

You should provide a contents property for objects such as windows and documents. When this property is requested (as in get the contents of window 1), you should return the entire contents of the object specified,if appropriate.

Text elements. When the object requested is a text element, such as a word or a character (as in get word 4 of paragraph 3 of document "Sales"), you should return the contents of the object itself as a string, such as "Fred" (word) or "x" (character).

Graphics objects. When the object requested is a simple graphics object where a standard format is in widespread use, you should return the contents of the object itself, just as for text elements. For example, for a PICT you would return the picture's data; for a point or a rectangle you would return a list of integers. When the object requested is a compound graphics object, such as a grouped graphic, you should return a reference to the object, in the form of an object specifier.

Cells, fields, and form elements. You should provide a value property for objects such as cells in a spreadsheet, fields in a database, or elements of a form. (In essence, this property is the same thing as the contents property, but in natural language, people usually refer to the value of a cell or field and the contents of a window. Making a distinction between these two kinds of properties thus preserves a natural language style.) When this property is requested (for instance,get the value of cell 3 of row 7), you should provide the content data for the object specified. If you want script writers to be able to get the value in more than one form, provide the as parameter (for example,get the value of . . . as styled text).

Rows, records, and entire forms. When a row or column in a spreadsheet or table, a record in a database, or an entire form is requested, you can return a list of the data values in each field (for example,get record 43 of database "Employees"might return {"Fred", 45.00}). However, it might be more appropriate to return a reference to the object, since the list might be too large or might contain large data. By the same token, either a list or a reference should be returned when the current record property that some developers have implemented is requested.

An object's internal data. Rather than dealing with raw internal data structures, script writers should be able to get any piece of attribute data for an object through the object's properties, by using the get <property> construct. If you want to let them get all the attribute data at once with a single get command, provide a properties property (as, for example, QuarkXPress does), return a record with the values for all the properties, and provide a definition for the record as a new abstract class in the Type Definitions suite (discussed in my article in Issue 21).

As you can see, it's not always clear how to respond to an object request. While not a hard rule, the basic guideline is this: If an object is an elementary piece of data, such as a word or a rectangle, return its value directly; if it's a structure, such as a record or a row, return a list of its values or a reference to the structure; and if it's a complex or abstract object (especially part of the user interface like a window or a button), return either an error or a reference to the object. What you decide to return will often depend on the way you want script sentences to read.

How to create and extract object specifiers from Apple events is explained inInside Macintosh: Interapplication Communication . The outermost container for an object specifier is always the application itself, represented by a container of type typeNull. A null container is the only proper way to specify the application level of the containment; do not include a cApplication object specifier as a container. Figure 1 illustrates the rightway to specify the application as a container. The wrong way in this case would be to have a third container level labeled cApplication between cDocument and cNull.

Figure 1. [IMAGE 081-082_According_to_Scri2.GIF]

Specifying the application as a container

Remember, everything you do in your event handlers, your object accessor functions, your error messages, and your dictionary will significantly affect the experience your users have in writing scripts. In future columns, I'll be discussing how to organize your dictionary; the increasingly crowded naming space for terms; how to organize and propose a new standard suite, event, or object definition; recording; and, as always, more tips, tricks, and conventions.

CAL SIMONE (AppleLink MAIN.EVENT) spends a lot of time helping others make sense of AppleScript, escaping from Washington DC about once a month to promote or teach AppleScript. He lives in Adams-Morgan, the city's only real ethnic neighborhood; full of cultural diversity, it boasts 45 restaurants representing 18 different nationalities in just one block.*

Thanks to Sue Dumont and Jon Pugh for reviewing this column. *


Community Search:
MacTech Search:

Software Updates via MacUpdate

AirPort Utility 6.3.6 - Set up and manag...
Note: Most recent release available only within OS X 10.11 El Capitan update. Use AirPort Utility to set up and manage your Wi-Fi network and AirPort base stations, including AirPort Express, AirPort... Read more
Quicksilver 1.3.1 - Application launcher...
Quicksilver is a light, fast and free Mac application that gives you the power to control your Mac with keystrokes alone. Quicksilver allows you to find what you need quickly and easily, then act... Read more
Tidy Up (Five Users) 4.1.5 - Find duplic...
Tidy Up is a complete duplicate finder and disk-tidiness utility. With Tidy Up you can search for duplicate files and packages by the owner application, content, type, creator, extension, time... Read more
Mellel 3.4.3 - The word processor of cho...
Mellel is the leading word processor for OS X and has been widely considered the industry standard since its inception. Mellel focuses on writers and scholars for technical writing and multilingual... Read more
Skype - Voice-over-internet p...
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
Bookends 12.6.0 - Reference management a...
Bookends is a full-featured bibliography/reference and information-management system for students and professionals. Access the power of Bookends directly from Mellel, Nisus Writer Pro, or MS Word (... Read more
Apple iBooks Author 2.4 - Create and pub...
Apple iBooks Author helps you create and publish amazing Multi-Touch books for iPad. Now anyone can create stunning iBooks textbooks, cookbooks, history books, picture books, and more for iPad. All... Read more
Web Snapper 3.3.9 - Capture entire Web p...
Web Snapper lets you capture Web pages exactly as they appear in your browser. You can send them to a file as images or vector-based, multi-page PDFs. It captures the whole Web page - eliminating the... Read more
Tunnelblick 3.6beta10 - GUI for OpenVPN...
Tunnelblick is a free, open source graphic user interface for OpenVPN on OS X. It provides easy control of OpenVPN client and/or server connections. It comes as a ready-to-use application with all... Read more
EtreCheck 2.5.1 - For troubleshooting yo...
EtreCheck is a simple little app to display the important details of your system configuration and allow you to copy that information to the Clipboard. It is meant to be used with Apple Support... Read more

Camel Up (Games)
Camel Up 1.0.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.0 (iTunes) Description: | Read more »
The Martian: Bring Him Home (Games)
The Martian: Bring Him Home 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: Based on the best selling novel and critically acclaimed film, THE MARTIAN tells the story of Astronaut Mark... | Read more »
This Week at 148Apps: September 21-30, 2...
Leap Into Fall 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... | Read more »
Tweetbot 4 for Twitter (Social Networki...
Tweetbot 4 for Twitter 4.0 Device: iOS Universal Category: Social Networking Price: $4.99, Version: 4.0 (iTunes) Description: *** 50% off for a limited time. *** | Read more »
Mori (Games)
Mori 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: Stop, rewind and unwind with Mori. Time is always running, take a moment to take control. Mori is an action puzzle game about infinitely... | Read more »
100 Years' War (Games)
100 Years' War 1.0 Device: iOS Universal Category: Games Price: $3.99, Version: 1.0 (iTunes) Description: | Read more »
Tower in the Sky (Games)
Tower in the Sky 0.0.60 Device: iOS Universal Category: Games Price: $1.99, Version: 0.0.60 (iTunes) Description: | Read more »
hocus. (Games)
hocus. 1.0.0 Device: iOS Universal Category: Games Price: $.99, Version: 1.0.0 (iTunes) Description: New, polished, mind-bending, minimal puzzle game with dozens of levels and extra-ordinary design Features:- Beautifully crafted... | Read more »
Mos Speedrun 2 (Games)
Mos Speedrun 2 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: Mos is back, in her biggest and most exciting adventure ever! Wall-jump to victory through 30 mysterious, action packed levels... | Read more »
3D Touch could be a game-changer, but it...
Were you one of the lucky/financially secure enough ones to buy a new iPhone 6s or iPhone 6s Plus over the weekend? Yup, me too (I’m not convinced I was either of those two things, but let’s go with lucky for now), so I thought I’d delve into just... | Read more »

Price Scanner via

Apple refurbished iPad Air 2s available for u...
Apple has Certified Refurbished iPad Air 2s available for up to $140 off the price of new models. Apple’s one-year warranty is included with each model, and shipping is free: - 128GB Wi-Fi iPad Air 2... Read more
Save up to $100 on Mac AppleCare Protection P...
Adorama has 3-Year AppleCare Warranties on sale for up to $100 off MSRP including free shipping plus NY & NJ sales tax only: - Mac Laptops 15″ and Above: $249 $100 off MSRP - Mac Laptops 13″ and... 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
12-inch MacBooks in stock for up to $120 off,...
Adorama has 12″ Retina MacBooks in stock for up to $120 off MSRP including free shipping plus NY & NJ sales tax only. For a limited time, Adorama will include a free Apple USB-C to USB Adapter,... Read more
15-inch 2.2GHz Retina MacBook Pro on sale for... has the 15″ 2.2GHz Retina MacBook Pro on sale for $1799 including free shipping. Their price is $200 off MSRP, and it’s the lowest price available for this model (except for Apple’s $1699... Read more
iPhone 6s and 6s Plus Feature Improved Durabi...
Upgraded components in the new iPhone 6s Plus cost $16 more than the components in the earlier iPhone 6 Plus according to a preliminary estimate from IHS Inc. The bill of materials (BOM) for an... Read more
13-inch Retina MacBook Pros on sale for up to...
Adorama has 13″ Retina MacBook Pros on sale for up to $130 off MSRP. Shipping is free, and Adorama charges sales tax for NY & NJ residents only: - 13″ 2.7GHz/128GB Retina MacBook Pro: $1199.99 $... Read more
Apple refurbished 2014 13-inch Retina MacBook...
Apple has Certified Refurbished 2014 13″ 2.6GHz/128GB SSD Retina MacBook Pros available $979, $320 off original MSRP. An Apple one-year warranty is included, and shipping is free: - 13″ 2.6GHz/128GB... Read more
iOS 9 Reflections Ten Days In – The ‘Book Mys...
I’ve never been much of an early adopter by philosophy or temperament, although I did buy the iPad Air 2 I’m typing this column on last fall only about a month after Apple unveiled it. However, my... Read more
Apple refurbished Time Capsules available for...
Apple has certified refurbished Time Capsules available for $120 off MSRP. Apple’s one-year warranty is included with each Time Capsule, and shipping is free: - 2TB Time Capsule: $179, $120 off - 3TB... Read more

Jobs Board

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
*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* Site Security Manager - Apple (Unite...
**Job Summary** The Site Security Manager is a high-profile security position at Apple . The Site Manager is the face of Apple Global Security (GS) and primary point Read more
*Apple* Fulfillment Operations Execution Ana...
**Job Summary** The AMR Apple Fulfillment Operations Team is seeking a talented team player to drive the Apple Online Store (AOS) fulfillment performance to ensure a Read more
*Apple* Distinguished Educator (ADE) Communi...
**Job Summary** Apple is seeking candidates for a new position on the Apple Distinguished Educator (ADE) Program team as ADE Community Support Manager. Join a team Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.