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

DiskCatalogMaker 7.2.7 - Catalog your di...
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 for... Read more
Iridient Developer 3.2.1 - Powerful imag...
Iridient Developer (was RAW Developer) is a powerful image-conversion application designed specifically for OS X. Iridient Developer gives advanced photographers total control over every aspect of... Read more
BusyContacts 1.2.7 - Fast, efficient con...
BusyContacts is a contact manager for OS X that makes creating, finding, and managing contacts faster and more efficient. It brings to contact management the same power, flexibility, and sharing... Read more
MegaSeg 6.0.5 - Professional DJ and radi...
MegaSeg is a complete solution for pro audio/video DJ mixing, radio automation, and music scheduling with rock-solid performance and an easy-to-use design. Mix with visual waveforms and Magic... Read more
BusyContacts 1.2.7 - Fast, efficient con...
BusyContacts is a contact manager for OS X that makes creating, finding, and managing contacts faster and more efficient. It brings to contact management the same power, flexibility, and sharing... Read more
MegaSeg 6.0.5 - Professional DJ and radi...
MegaSeg is a complete solution for pro audio/video DJ mixing, radio automation, and music scheduling with rock-solid performance and an easy-to-use design. Mix with visual waveforms and Magic... Read more
Iridient Developer 3.2.1 - Powerful imag...
Iridient Developer (was RAW Developer) is a powerful image-conversion application designed specifically for OS X. Iridient Developer gives advanced photographers total control over every aspect of... Read more
iFFmpeg 6.6.1 - Convert multimedia files...
iFFmpeg is a comprehensive media tool to convert movie, audio and media files between formats. The FFmpeg command line instructions can be very hard to master/understand, so iFFmpeg does all the hard... Read more
Tor Browser Bundle 7.0.11 - Anonymize We...
The Tor Browser Bundle is an easy-to-use portable package of Tor, Vidalia, Torbutton, and a Firefox fork preconfigured to work together out of the box. It contains a modified copy of Firefox that... Read more
iShowU Instant 1.2.4 - Full-featured scr...
iShowU Instant gives you real-time screen recording like you've never seen before! It is the fastest, most feature-filled real-time screen capture tool from shinywhitebox yet. All of the features you... Read more

Latest Forum Discussions

See All

Reigns: Her Majesty guide - how to use e...
Ruling a kingdom isn't easy--doubly so for a queen whose every decision is questioned by the other factions seeking a slice of power. Reigns: Her Majesty builds on the original game's swipey tactics, adding items that you can use to move the story... | Read more »
The best new games we played this week -...
Friday has crept up on us once again, so it's time to honor the best new games we've played over the past few days. This past week was a pretty exciting one, with the debut of lots of beautiful new indies and some familiar faces returning to the... | Read more »
Portal Knights guide- beginner tips and...
Portal Knights is finally making the jump to iOS and Android, and it's already climbing the ranks to become the next big MMO experience on mobile. This sprawling sandbox game will let you pursue any adventure you wish, whether you want to sling... | Read more »
Reigns: Her Majesty guide - how to swipe...
Reigns: Her Majesty is storming the App Store this week, bringing more tinder-esque kingdom building to eager players everywhere. If you've played the original Reigns, you'll know that leading a kingdom is never easy. It's a careful balancing act... | Read more »
Getting Over It (Games)
Getting Over It 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: A game I madeFor a certain kind of person To hurt them. • Climb up an enormous mountain with nothing but a hammer and a pot.•... | Read more »
Reigns: Her Majesty (Games)
Reigns: Her Majesty 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: | Read more »
Pocket Legends Adventures guide - how to...
Pocket Legends Adventures is a fun action adventure RPG that takes control when you want it to, but also opens itself for player input, too, if you're looking to tkae a more active role in combat. Regardless of play style, the game can be quite... | Read more »
Portal Knights (Games)
Portal Knights 1.2.4 Device: iOS Universal Category: Games Price: $4.99, Version: 1.2.4 (iTunes) Description: Craft your adventure. Forge your hero. Become the ultimate Portal Knight! | Read more »
Ashworld (Games)
Ashworld 1.3 Device: iOS Universal Category: Games Price: $3.99, Version: 1.3 (iTunes) Description: | Read more »
The best deals on the App Store this wee...
Another week means another roundup of quality bargain games. This week's list features a few games we haven't featured before in our weekly roundups. If you're on the prowl for new games, now's an optimal time to try something completely new for... | Read more »

Price Scanner via MacPrices.net

Beats by Dr. Dre – BeatsX Earphones on sale f...
Best Buy has BeatsX Earphones on sale for $109, $40 off, on their online store. Sale price for online orders only. Choose free store pickup, if available, or choose free shipping. Read more
10″ 64GB WiFi Apple iPad Pros on sale for $59...
MacMall has 10.5″ 64GB Apple iPad Pros on sale for $599 including free shipping. That’s $50 off MSRP and among the lowest prices available for these iPads from any Apple reseller. Read more
15″ 2.2GHz MacBook Pros on sale for $200-$300...
B&H Photo has the 15″ 2.2GHz MacBook Pro available for $200 off MSRP including free shipping plus NY & NJ sales tax only: – 15″ 2.2GHz MacBook Pro (MJLQ2LL/A): $1799 $200 off MSRP Apple has... Read more
Holiday sale: 15″ MacBook Pros for $200-$420...
MacMall has 15″ MacBook Pros on sale for $220-$300 off MSRP, each including free shipping: – 15″ 2.8GHz MacBook Pro Space Gray (MPTR2LL/A): $2179, $220 off MSRP – 15″ 2.8GHz MacBook Pro Silver (... Read more
Holiday sale: 13″ MacBook Airs for up to $150...
B&H Photo has 13″ MacBook Airs on sale for $100 off MSRP as part of their Holiday sale. Shipping is free, and B&H charges sales tax for NY & NJ residents only: – 13″ 1.8GHz/128GB MacBook... Read more
The best Holiday sale prices on 13″ MacBook P...
B&H Photo has 13″ MacBook Pros on sale this weekend, with models available for $100-$150 off MSRP. Shipping is free, and B&H charges sales tax for NY & NJ residents only: – 13-inch 2.3GHz... Read more
Holiday sale: 27″ Apple iMacs for $150-$200 o...
MacMall has 27″ iMacs on sale for $150-$200 off MSRP as part of their Holiday sale, each including free shipping: – 27″ 3.8GHz iMac (MNED2LL/A): $2099 $200 off MSRP – 27″ 3.5GHz iMac (MNEA2LL/A): $... Read more
Save on clearance 2016 15″ MacBook Pros, up t...
B&H Photo has clearance 2016 15″ MacBook Pros available for up to $700 off original MSRP. Shipping is free, and B&H charges NY & NJ sales tax only: – 15″ 2.7GHz Touch Bar MacBook Pro... Read more
Apple offers Certified Refurbished 9.7″ iPads...
Apple has Certified Refurbished 9.7″ WiFi iPads available for $50-$70 off the cost of new models. An Apple one-year warranty is included with each iPad, and shipping is free: – 9″ 32GB WiFi iPad: $... Read more
Save $200-$240 on a 12″ Apple MacBook with Ce...
Apple has Certified Refurbished 2017 12″ Retina MacBooks available for $200-$240 off the cost of new models. Apple will include a standard one-year warranty with each MacBook, and shipping is free.... Read more

Jobs Board

*Apple* Retail - Multiple Positions - Apple,...
Job Description:SalesSpecialist - Retail Customer Service and SalesTransform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
*Apple* Retail - Multiple Positions - Apple,...
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* Retail - Multiple Positions - Apple,...
Job Description:SalesSpecialist - Retail Customer Service and SalesTransform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
*Apple* Information Security - Security Data...
# Apple Information Security - Security Data Analyst Job Number: 113119545 Austin, Texas, United States Posted: 10-Nov-2017 Weekly Hours: 40.00 **Job Summary** This Read more
*Apple* Retail - Multiple Positions - Apple,...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.