TweetFollow Us on Twitter

June 95 - ACCORDING TO SCRIPT

ACCORDING TO SCRIPT

Scripting Quandaries

CAL SIMONE

[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.

STARTING WITH MENU COMMANDS
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.

LOWERCASING VERBS, TOO
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.

HANDLING REQUESTS TO GET AN OBJECT
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.

THE APPLICATION AS CONTAINER
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



I'M OUTTA SPACE
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

Microsoft Remote Desktop 8.0.16 - Connec...
With Microsoft Remote Desktop, you can connect to a remote PC and your work resources from almost anywhere. Experience the power of Windows with RemoteFX in a Remote Desktop client designed to help... Read more
Spotify 1.0.4.90. - Stream music, create...
Spotify is a streaming music service that gives you on-demand access to millions of songs. Whether you like driving rock, silky R&B, or grandiose classical music, Spotify's massive catalogue puts... Read more
djay Pro 1.1 - Transform your Mac into a...
djay Pro provides a complete toolkit for performing DJs. Its unique modern interface is built around a sophisticated integration with iTunes and Spotify, giving you instant access to millions of... Read more
Vivaldi 1.0.118.19 - Lightweight browser...
Vivaldi browser. In 1994, two programmers started working on a web browser. Our idea was to make a really fast browser, capable of running on limited hardware, keeping in mind that users are... Read more
Stacks 2.6.11 - New way to create pages...
Stacks is a new way to create pages in RapidWeaver. It's a plugin designed to combine drag-and-drop simplicity with the power of fluid layout. Features: Fluid Layout: Stacks lets you build pages... Read more
xScope 4.1.3 - Onscreen graphic measurem...
xScope is powerful set of tools that are ideal for measuring, inspecting, and testing on-screen graphics and layouts. Its tools float above your desktop windows and can be accessed via a toolbar,... Read more
Cyberduck 4.7 - FTP and SFTP browser. (F...
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
Labels & Addresses 1.7 - Powerful la...
Labels & Addresses is a home and office tool for printing all sorts of labels, envelopes, inventory labels, and price tags. Merge-printing capability makes the program a great tool for holiday... Read more
teleport 1.2.1 - Use one mouse/keyboard...
teleport is a simple utility to let you use one single mouse and keyboard to control several of your Macs. Simply reach the edge of your screen, and your mouse teleports to your other Mac! The... Read more
Apple iMovie 10.0.8 - Edit personal vide...
With an all-new design, Apple iMovie lets you enjoy your videos like never before. Browse your clips more easily, instantly share your favorite moments, and create beautiful HD movies and Hollywood-... Read more

Use Batting Average and the Apple Watch...
Batting Average, by Pixolini, is designed to help you manage your statistics. Every time you go to bat, you can use your Apple Watch to track  your swings, strikes, and hits. [Read more] | Read more »
Celebrate Studio Pango's 3rd Annive...
It is time to party, Pangoland pals! Studio Pango is celebrating their 3rd birthday and their gift to you is a new update to Pangoland. [Read more] | Read more »
Become the World's Most Important D...
Must Deliver, by cherrypick games, is a top-down endless-runner witha healthy dose of the living dead. [Read more] | Read more »
SoundHound + LiveLyrics is Making its De...
SoundHound Inc. has announced that SoundHound + LiveLyrics, will be one of the first third-party apps to hit the Apple Watch. With  SoundHound you'll be able to tap on your watch and have the app recognize the music you are listening to, then have... | Read more »
Adobe Joins the Apple Watch Lineup With...
A whole tidal wave of apps are headed for the Apple Watch, and Adobe has joined in with 3 new ways to enhance your creativity and collaborate with others. The watch apps pair with iPad/iPhone apps to give you total control over your Adobe projects... | Read more »
Z Steel Soldiers, Sequel to Kavcom'...
Kavcom has released Z Steel Soldiers, which continues the story of the comedic RTS originally created by the Bitmap Brothers. [Read more] | Read more »
Seene Lets You Create 3D Images With You...
Seene, by Obvious Engineering, is a 3D capture app that's meant to allow you to create visually stunning 3D images with a tap of your finger, and then share them as a 3D photo, video or gif. [Read more] | Read more »
Lost Within - Tips, Tricks, and Strategi...
Have you just downloaded Lost Within and are you in need of a guiding hand? While it’s not the toughest of games out there you might still want some helpful tips to get you started. [Read more] | Read more »
Entertain Your Pet With Your Watch With...
The Petcube Camera is a device that lets you use live video to check in on your pet, talk to them, and play with them using a laser pointer - all while you're away. And the Petcube app is coming to the Apple Watch, so you'll be able to hang out with... | Read more »
Now You Can Manage Your Line2 Calls With...
You'll be able to get your Line2 cloud phone service on the Apple Watch very soon. The watch app can send and receive messages using hands-free voice dictation, or by selecting from a list of provided responses. [Read more] | Read more »

Price Scanner via MacPrices.net

Intel Compute Stick: A New Mini-Computing For...
The Intel Compute Stick, a new pocket-sized computer based on a quad-core Intel Atom processor running Windows 8.1 with Bing, is available now through Intel Authorized Dealers across much of the... Read more
Heal to Launch First One-Touch House Call Doc...
Santa Monica, California based Heal, a pioneer in on-demand personal health care services — will offer the first one-touch, on-demand house call doctor app for the Apple Watch. Heal’s Watch app,... Read more
Mac Notebooks: Avoiding MagSafe Power Adapter...
Apple Support says proper usage, care, and maintenance of Your Mac notebook’s MagSafe power adapter can substantially increase the the adapter’s service life. Of course, MagSafe itself is an Apple... Read more
12″ Retina MacBook In Shootout With Air And P...
BareFeats’ rob-ART morgan has posted another comparison of the 12″ MacBook with other Mac laptops, noting that the general goodness of all Mac laptops can make which one to purchase a tough decision... Read more
FileMaker Go for iPad and iPhone: Over 1.5 Mi...
FileMaker has announced that its FileMaker Go for iPad and iPhone app has surpassed 1.5 million downloads from the iTunes App Store. The milestone confirms the continued popularity of the FileMaker... Read more
Sale! 13-inch 2.7GHz Retina MacBook Pro for $...
 Best Buy has the new 2015 13″ 2.7GHz/128GB Retina MacBook Pro on sale for $1099 – $200 off MSRP. Choose free shipping or free local store pickup (if available). Price for online orders only, in-... Read more
Minimalist MacBook Confirms Death of Steve Jo...
ReadWrite’s Adriana Lee has posted a eulogy for the “Digital Hub” concept Steve Jobs first proposed back in 2001, declaring the new 12-inch MacBook with its single, over-subscribed USB-C port to be... Read more
13-inch 2.7GHz Retina MacBook Pro for $1234 w...
Adorama has the 13″ 2.7GHz/128GB Retina MacBook Pro in stock for $1234.99 ($65 off MSRP) including free shipping plus a free LG external DVD/CD optical drive. Adorama charges sales tax in NY & NJ... Read more
13-inch 2.5GHz MacBook Pro available 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
Save up to $600 with Apple refurbished Mac Pr...
The Apple Store is offering Apple Certified Refurbished Mac Pros for up to $600 off the cost of new models. An Apple one-year warranty is included with each Mac Pro, and shipping is free. The... Read more

Jobs Board

*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
*Apple* Support Technician IV - Jack Henry a...
Job Description Jack Henry & Associates is seeking an Apple Support Technician. This position while acting independently, ensures the proper day-to-day control of Read more
*Apple* Client Systems Solution Specialist -...
…drive revenue and profit in assigned sales segment and/or region specific to the Apple brand and product sets. This person will work directly with CDW Account Managers Read more
*Apple* Software Support - Casper (Can work...
…experience . Full knowledge of Mac OS X and prior . Mac OSX / Server . Apple Remote Desktop . Process Documentation . Ability to prioritize multiple tasks in a fast pace Read more
*Apple* Software Support - Xerox Corporation...
…Imaging experience Full knowledge of Mac OS X and prior Mac OSX / Server Apple Remote Desktop Process Documentation Ability to prioritize multiple tasks in a fast pace Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.