TweetFollow Us on Twitter

June 96 - According to Script: Attaching and Embedding Scripts

According to Script: Attaching and Embedding Scripts

CAL SIMONE

One of the least-implemented powerful capabilities you can add to your application is attaching and embedding scripts. In this column I'll give you an idea of how to do this, and clear up some confusion along the way.

ATTACHING VS. EMBEDDING

The term attach has been used to refer to both attaching and embedding. Allow me to set the record straight by offering definitions of the two terms as they apply to scripting.
  • An attached script is a compiled script or script application that's associated with a menu item in an application; the script is executed when the user chooses that command. This type of script usually resides in a particular place, such as a Scripts folder. Script attachment can be implemented quickly and, at its most basic level, doesn't require your application to be scriptable.

  • An embedded script is a compiled script that's associated with an interface element belonging to an application or with a document. The script can be stored with the application's data, often in a special file known to the application, or embedded within the data for a document file.

ATTACHING SCRIPTS TO MENU ITEMS

Attached scripts are useful for two reasons. You, or your users (depending on what's appropriate for your application), can do the following:
  • Execute scripts to communicate with and control other scriptable applications without leaving your application. This is useful whether or not your application is scriptable.

  • Use scripts as an means of extending the functions or options available in your application. If your application itself is scriptable, script attachment leverages off the work you've already done.
By allowing users to keep a menu of their favorite scripts, you enable them to build a library of expanded functionality for your application. The Mac OS and Finder accomplish this with the Automated Tasks submenu in the Apple menu. You can do this with a Scripts menu that appears as the last (or next to last) of your application's menus.

Here are the steps for implementing this attachable behavior:

  • In the resource file included with your application, include a menu resource with the title "Scripts."

  • In the startup code for your application, locate the Scripts folder in your application's folder, creating it if it isn't there.

  • Walk the files in the Scripts folder, checking for compiled scripts (file type 'osas') and script applications (file type 'APPL', creator 'aplt' or 'dplt'). Add the names of these files to your Scripts menu.

  • When a user selects a script name from the Scripts menu, load the script resource ('scpt' 128) and execute the script, as shown in Listing 1.

Listing 1. Loading and executing a script from a file
FUNCTION RunAttachedScript(theAlias: AliasHandle): OSAError;
VAR
   fileSpec:             FSSpec;
   scriptRes:            Handle;
   scriptDesc:           AEDesc;
   scriptID, resultID:   OSAID;
   myErr, ignoredErr:    OSAError;
   savedRes, refNum:     Integer;
   specChanged:          Boolean;

BEGIN
   (* Get the file specification corresponding to the menu item chosen. *)
   myErr := ResolveAlias(NIL, theAlias, fileSpec, specChanged);
   IF myErr <> noErr THEN MyErrorProc(myErr);

   (* Open the resource fork and grab the script resource. *)
   savedRes := CurResFile;
   refNum := FSpOpenResFile(fileSpec, fsRdPerm);
   IF refNum = -1 THEN MyErrorProc(-1);
   UseResFile(refNum);
   scriptRes := Get1Resource(kOSAScriptResourceType, 128);
   IF ResError <> noErr THEN MyErrorProc(ResError);

   (* Prepare and run the script. *)
   myErr := AECreateDesc(typeOSAGenericStorage, scriptRes^, GetHandleSize(scriptRes),       scriptDesc);
   IF myErr <> noErr THEN MyErrorProc(myErr);
   myErr := OSALoad(gGenericComponent, scriptDesc, kOSAModeNull, scriptID);
   IF myErr <> noErr THEN MyErrorProc(myErr);
   myErr := OSAExecute(gGenericComponent, scriptID, kOSANullScript, kOSAModeNull, resultID);
   ignoredErr := OSADispose(gGenericComponent, scriptID);
   ignoredErr := AEDisposeDesc(scriptDesc);
   IF myErr <> noErr THEN MyErrorProc(myErr);

   (* Finish up. *)
   ReleaseResource(scriptRes);
   CloseResFile(refNum);
   UseResFile(savedRes);

   (* You might want to do something with the result. *)
   IF resultID <> kOSANullScript THEN MyDealWithResult(resultID);
   RunAttachedScript := myErr;
END;
Before executing a script, you must establish a connection to a scripting component. The easiest thing to do is to connect to the generic scripting component with OpenDefaultComponent. When you're done, disconnect from the component with CloseComponent. Depending on how you design your application, you can open this connection and keep it open while your program is running, or you can open and close the connection each time you load and execute a script. For more information on choosing and connecting scripting components, see Inside Macintosh: Interapplication Communication, Chapter 10.

EMBEDDED SCRIPTS IN APPLICATION DATA OR DOCUMENT FILES

Embedded scripts can be used in two ways:
  • Interface elements belonging to an application, such as tool palette icons, menu items, and buttons, can have scripts associated with them.

  • Scripts can be associated with individual documents. Unlike the above case, you can trigger the script with any method that's appropriate for your application.
Embedding scripts can be extremely powerful. For example, you can associate scripts with elements of a form to supply a field's editing rules, or with a button to perform calculations. Replace a script and you change the rules or the formula! Depending on your particular application, you can use this technique yourself or allow users to do their own replacement.

If you reserve this technique for your own use, you can revise your software simply by replacing scripts with corrected or enhanced versions. Or, if you allow your users to change the embedded scripts, your application becomes easily customizable: users can modify or augment your application's capabilities simply by substituting scripts. You could even ship your application with replacement scripts, which users can substitute for default scripts that you provide.

RETRIEVING EMBEDDED SCRIPTS

There are three methods of retrieving embedded scripts from files, depending on where they're stored. Regardless of which method you choose, it's important to remember that your program should never try to interpret the bytes of a compiled script. However, as long as you keep the bytes intact, you can do whatever you want with them and the script will remain intact.

Aliases to script files. This is the same technique as described above for attached scripts. This method is used primarily for maintaining a list of scripts. You'd use it, for instance, if you kept a collection of scripts in a folder on disk. I don't recommend this technique if the scripts are associated with actual interface elements, because the links that aliases provide to the script files can too easily be broken.

In the document's resource fork. Storing the scripts as resources is convenient because you can easily use your favorite resource editor to copy a script resource from a compiled script or script application and paste it into the special application file or the document. It also makes it easy to grab the scripts for loading and executing, using the method shown in Listing 1 (though in this situation I'd suggest using an ID number other than 128 for the script resource). The drawback is that your users can get their hands on the script with their favorite resource editor.

In the document's data fork. Maintaining the scripts within the data for a document is a more secure method, since it makes it harder for users to extract the scripts. It's also more difficult for you, though, because you may have to keep track of the location within the document's data, and then convert the script into the form required for execution. You'll want to store three pieces of information: the four-character ID 'scpt' (typeOSAGenericStorage), the length of the script data that follows, and the script data itself. The ID isn't essential, but it may come in handy, especially if there are other types of data present or if you load your document's data sequentially.

There are many ways to keep track of multiple types of data in a document file. If you have a lot of different types of data in the file, you can even develop a small database for the data, complete with a directory, so that you can gain quick access to particular types of data, including the script. A simpler way is to maintain the data in one long stream, embedding the script data within the stream. If you know the location of the script within the stream, you can just load and execute it when a user wants to run it. One developer I know reads all the data in the data fork (including scripts) sequentially when the file is opened, so that he doesn't need to keep track of the script's location within the file. Listing 2 shows an example of loading script data from the data fork of a document file.

Listing 2. Extracting script data from a document's data fork

FUNCTION RunEmbeddedScriptFromDataFork(theAlias: AliasHandle;
             scriptLoc: LongInt): OSAError;
VAR
   fileSpec:              FSSpec;
   scriptData:            Handle;
   scriptDesc:            AEDesc;
   dataType:              DescType;
   scriptID, resultID:    OSAID;
   myErr, ignoredErr:     OSAError;
   refNum:                Integer;
   scriptLen, readLen:    LongInt;
   specChanged:           Boolean;

BEGIN
   (* Open the file. *)
   myErr := ResolveAlias(NIL, theAlias, fileSpec, specChanged);
   IF myErr <> noErr THEN MyErrorProc(myErr);
   myErr := FSpOpenDF(fileSpec, fsRdPerm, refNum);
   IF myErr <> noErr THEN MyErrorProc(myErr);

   (* Grab the data. *)
   IF MemError <> noErr THEN MyErrorProc(MemError);
   myErr := SetFPos(refNum, fsFromStart, scriptLoc);
   readLen := sizeof(dataType);
   IF myErr = noErr THEN myErr := FSRead(refNum, readLen, @dataType);
   (* dataType should be typeOSAGenericStorage. *)
   readLen := sizeof(scriptLen);
   IF myErr = noErr
       THEN myErr := FSRead(refNum, readLen, @scriptLen);
   IF myErr = noErr THEN scriptData := NewHandle(scriptLen);
   IF MemError <> noErr THEN MyErrorProc(MemError);
   myErr := FSRead(refNum, scriptLen, scriptData^);
   IF myErr <> noErr THEN MyErrorProc(myErr);
   myErr := FSClose(refNum);

   (* Prepare and run the script. *)
   myErr := AECreateDesc(typeOSAGenericStorage, scriptData^,
      GetHandleSize(scriptData), scriptDesc);
   DisposeHandle(scriptData);
   IF myErr <> noErr THEN MyErrorProc(myErr);
   myErr := OSALoad(gGenericComponent, scriptDesc, kOSAModeNull,
      scriptID);
   IF myErr <> noErr THEN MyErrorProc(myErr);
   myErr := OSAExecute(gGenericComponent, scriptID, kOSANullScript,
      kOSAModeNull, resultID);
   ignoredErr := OSADispose(gGenericComponent, scriptID);
   ignoredErr := AEDisposeDesc(scriptDesc);
   IF myErr <> noErr THEN MyErrorProc(myErr);

   (* You might want to do something with the result. *)
   IF resultID <> kOSANullScript
      THEN MyDealWithResult(resultID);
   RunEmbeddedScriptFromDataFork := myErr;
END;

GIVING IT AWAY

The information in this column is not offered as a complete solution, but is intended to get you moving with implementing attachability. There are many other issues surrounding attachability that are worth exploring, such as getting time during script execution, using attached scripts to allow users to tinker with some of the core functionality of your application, and providing a consistent way for your users to edit attached and embedded scripts. I plan to delve into these other issues in upcoming columns.

Making your application capable of attaching or embedding scripts puts new power into your users' hands, giving them unprecedented ability to develop custom solutions to their problems. It's not hard to do, and the benefits are enormous. Do it today.

CAL SIMONE (mainevent@his.com, AppleLink MAIN.EVENT) Few people know it, but before Cal was in the software business, he used to produce records (the musical kind) in Washington DC and New York. At a time when computers were used mostly to make robotic dance music, Cal was one of the first to painstakingly create "human" performances in pop records with about 60 MIDI synthesizers and, of course, a Macintosh. He now works toward a day when every application will be scriptable.*

 
AAPL
$97.67
Apple Inc.
+0.64
MSFT
$44.50
Microsoft Corpora
+0.10
GOOG
$589.02
Google Inc.
-4.33

MacTech Search:
Community Search:

Software Updates via MacUpdate

TinkerTool 5.3 - Expanded preference set...
TinkerTool is an application that gives you access to additional preference settings Apple has built into Mac OS X. This allows to activate hidden features in the operating system and in some of the... Read more
Audio Hijack Pro 2.11.0 - Record and enh...
Audio Hijack Pro drastically changes the way you use audio on your computer, giving you the freedom to listen to audio when you want and how you want. Record and enhance any audio with Audio Hijack... Read more
Intermission 1.1.1 - Pause and rewind li...
Intermission allows you to pause and rewind live audio from any application on your Mac. Intermission will buffer up to 3 hours of audio, allowing users to skip through any assortment of audio... Read more
Autopano Giga 3.6 - Stitch multiple imag...
Autopano Giga allows you to stitch 2, 20, or 2,000 images. Version 3.0 integrates impressive new features that will definitely make you adopt Autopano Pro or Autopano Giga: Choose between 9... Read more
Airfoil 4.8.7 - Send audio from any app...
Airfoil allows you to send any audio to AirPort Express units, Apple TVs, and even other Macs and PCs, all in sync! It's your audio - everywhere. With Airfoil you can take audio from any... Read more
Microsoft Remote Desktop 8.0.8 - Connect...
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
xACT 2.30 - Audio compression toolkit. (...
xACT stands for X Aaudio Compression Toolkit, an application that encodes and decodes FLAC, SHN, Monkey’s Audio, TTA, Wavpack, and Apple Lossless files. It also can encode these formats to MP3, AAC... Read more
Firefox 31.0 - Fast, safe Web browser. (...
Firefox for Mac 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... Read more
Little Snitch 3.3.3 - Alerts you to outg...
Little Snitch gives you control over your private outgoing data. Track background activityAs soon as your computer connects to the Internet, applications often have permission to send any... Read more
Thunderbird 31.0 - Email client from Moz...
As of July 2012, Thunderbird has transitioned to a new governance model, with new features being developed by the broader free software and open source community, and security fixes and improvements... Read more

Latest Forum Discussions

See All

Jacob Jones and the Bigfoot Mystery : Ep...
Jacob Jones and the Bigfoot Mystery : Episode 2 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: Jacob Jones is back in Episode 2 of one of Apples 'Best of 2013' games and an App Store... | Read more »
New Trailer For Outcast Odyssey, A New K...
New Trailer For Outcast Odyssey, A New Kind of Card Battler Posted by Jennifer Allen on July 25th, 2014 [ permalink ] Out this Fall is a new kind of card battle game: Outcast Odyssey. | Read more »
Garfield: Survival of the Fattest Coming...
Garfield: Survival of the Fattest Coming to iOS this Fall Posted by Jennifer Allen on July 25th, 2014 [ permalink ] Who loves lasagna? Me. Also everyone’s favorite grumpy fat cat, Garfield. | Read more »
Happy Flock Review
Happy Flock Review By Andrew Fisher on July 25th, 2014 Our Rating: :: HERD IT ALL BEFOREUniversal App - Designed for iPhone and iPad Underneath the gloss of Happy Flock’s visuals is a game of very little substance. It’s cute, but... | Read more »
Square Register Updates Adds Offline Pay...
Square Register Updates Adds Offline Payments Posted by Ellis Spice on July 25th, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Looking For Group – Hearthstone’s Curse...
For the first time since its release (which has thankfully been a much shorter window for iPad players than their PC counterparts), Blizzard’s wildly successful Hearthstone: Heroes of Warcraft CCG is sporting some brand new content: the single... | Read more »
Poptile Review
Poptile Review By Jennifer Allen on July 25th, 2014 Our Rating: :: SIMPLY FUNUniversal App - Designed for iPhone and iPad Simple yet a little bit glorious, Poptile is a satisfying entertaining puzzle game with oodles of the ‘one... | Read more »
Modern Combat 5: Blackout Review
Modern Combat 5: Blackout Review By Brittany Vincent on July 25th, 2014 Our Rating: :: LESS QQ, MORE PEW PEWUniversal App - Designed for iPhone and iPad The fifth entry into the blockbuster Modern Combat series is what mobile... | Read more »
Watch and Share Mobile Gameplay Videos W...
Watch and Share Mobile Gameplay Videos With Kamcord Posted by Jennifer Allen on July 25th, 2014 [ permalink ] iPhone App - Designed for the iPhone, compatible with the iPad | Read more »
THE KING OF FIGHTERS '98 (Games)
THE KING OF FIGHTERS '98 1.0 Device: iOS Universal Category: Games Price: $3.99, Version: 1.0 (iTunes) Description: Series’ masterpiece “KOF ’98” finally joins the battle on iPhone! FEATURES:■ The best game balance in the “KOF”... | Read more »

Price Scanner via MacPrices.net

iMacs on sale for $150 off MSRP, $250 off for...
Best Buy has iMacs on sale for up to $160 off MSRP for a limited time. Choose free home shipping or free instant local store pickup (if available). Prices are valid for online orders only, in-store... Read more
Mac minis on sale for $100 off MSRP, starting...
Best Buy has Mac minis on sale for $100 off MSRP. Choose free shipping or free instant local store pickup. Prices are for online orders only, in-store prices may vary: 2.5GHz Mac mini: $499.99 2.3GHz... Read more
Global Tablet Market Grows 11% in Q2/14 Notwi...
Worldwide tablet sales grew 11.0 percent year over year in the second quarter of 2014, with shipments reaching 49.3 million units according to preliminary data from the International Data Corporation... Read more
New iPhone 6 Models to Have Staggered Release...
Digitimes’ Cage Chao and Steve Shen report that according to unnamed sources in Apple’s upstream iPhone supply chain, the new 5.5-inch iPhone will be released several months later than the new 4.7-... Read more
New iOS App Helps People Feel Good About thei...
Mobile shoppers looking for big savings at their favorite stores can turn to the Goodshop app, a new iOS app with the latest coupons and deals at more than 5,000 online stores. In addition to being a... Read more
Save on 5th generation refurbished iPod touch...
The Apple Store has Apple Certified Refurbished 5th generation iPod touches available starting at $149. Apple’s one-year warranty is included with each model, and shipping is free. Many, but not all... Read more
What Should Apple’s Next MacBook Priority Be;...
Stabley Times’ Phil Moore says that after expanding its iMac lineup with a new low end model, Apple’s next Mac hardware decision will be how it wants to approach expanding its MacBook lineup as well... Read more
ArtRage For iPhone Painting App Free During C...
ArtRage for iPhone is currently being offered for free (regularly $1.99) during Comic-Con San Diego #SDCC, July 24-27, in celebration of the upcoming ArtRage 4.5 and other 64-bit versions of the... Read more
With The Apple/IBM Alliance, Is The iPad Now...
Almost since the iPad was rolled out in 2010, and especially after Apple made a 128 GB storage configuration available in 2012, there’s been debate over whether the iPad is a serious tool for... Read more
MacBook Airs on sale starting at $799, free s...
B&H Photo has the new 2014 MacBook Airs on sale for up to $100 off MSRP for a limited time. Shipping is free, and B&H charges NY sales tax only. They also include free copies of Parallels... Read more

Jobs Board

*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
Sr. Project Manager for *Apple* Campus 2 -...
…the design and construction of one building or building components of the New Apple Campus located in Cupertino, CA. They will provide project management oversight for Read more
WW Sales Program Manager, *Apple* Online St...
**Job Summary** Imagine what you could do here. At Apple , great ideas have a way of becoming great products, services, and customer experiences very quickly. Bring Read more
*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.