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
$109.41
Apple Inc.
+2.67
MSFT
$45.74
Microsoft Corpora
+0.58
GOOG
$504.89
Google Inc.
+9.50

MacTech Search:
Community Search:

Software Updates via MacUpdate

Command-C 1.1.7 - Clipboard sharing tool...
Command-C is a revolutionary app which makes easy to share your clipboard between iOS and OS X using your local WiFi network, even if the app is not currently opened. Copy anything (text, pictures,... Read more
Tidy Up 4.0.2 - Find duplicate files and...
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
Typinator 6.3 - Speedy and reliable text...
Typinator turbo-charges your typing productivity. Type a little. Typinator does the rest. We've all faced projects that require repetitive typing tasks. With Typinator, you can store commonly used... Read more
GraphicConverter 9.5 - Graphics editor w...
GraphicConverter is an all-purpose image-editing program that can import 200 different graphic-based formats, edit the image, and export it to any of 80 available file formats. The high-end editing... Read more
Toast Titanium 12.0.1 - The ultimate med...
Toast Titanium goes way beyond the very basic burning in the Mac OS and iLife software, and sets the standard for burning CDs, DVDs, and now Blu-ray discs on the Mac. Create superior sounding audio... Read more
QuickBooks 2015 16.0.2.1422 R3 - Financi...
Save 20% on QuickBooks Pro for Mac today through this special discount link QuickBooks Pro 2013 helps you manage your business easily and efficiently. Organize your finances all in one place, track... Read more
Remotix 3.0.6 - Access all your computer...
Remotix is a fast and powerful application to easily access multiple Macs (and PCs) from your own Mac. Features: Complete Apple Screen Sharing support - including Mac OS X login, clipboard... Read more
BetterZip Quick Look Generator 1.5 - Let...
BetterZip Quick Look Generator lets you view the contents of compressed archives through OS X's Quick Look functions. Simply select an archive in the Finder, in Mail, or Spotlight and press the... Read more
Sandvox 2.9.3 - Easily build eye-catchin...
Sandvox is for Mac users who want to create a professional looking website quickly and easily. With Sandvox, you don't need to be a Web genius to build a stylish, feature-rich, standards-compliant... Read more
Pixelmator 3.3.1 - Powerful layer-based...
Pixelmator is a beautifully designed, easy-to-use, fast, and powerful image editor for OS X. It has everything you need to create, edit, and enhance your images. Pixelmator is a layer-based image... Read more

Latest Forum Discussions

See All

Pentaction: Medieval (Games)
Pentaction: Medieval 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: Pentaction: Medieval is a turn-based strategy board-game about chance and skill on the battlefield. Take control of your... | Read more »
Hipstify Review
Hipstify Review By Jennifer Allen on December 17th, 2014 Our Rating: :: COOL FILTERSUniversal App - Designed for iPhone and iPad Add filters, quotes, and fancy frames to your images, thanks to Hipstify.   | Read more »
Mighty Smighties Gets Evolve Cards and N...
Mighty Smighties Gets Evolve Cards and New Worlds Posted by Jessica Fisher on December 17th, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Duckie Deck Card Wars Review
Duckie Deck Card Wars Review By Amy Solomon on December 17th, 2014 Our Rating: :: STYLISH GAME OF CARDSUniversal App - Designed for iPhone and iPad Duckie Deck Card Wars adapts the classic card game War for use on devices, complete... | Read more »
PDF Office Review
PDF Office Review By Jennifer Allen on December 17th, 2014 Our Rating: :: CONVENIENT PDF EDITINGiPad Only App - Designed for the iPad Want to create your own PDF files? Import them from elsewhere? Adapt a web page into a PDF? PDF... | Read more »
The Out There: Ω Edition Update will be...
The Out There: Ω Edition Update will be Releasing in 2015, Bringing Better Graphics and Additional Content Posted by Jessica Fisher on December 17th, 2014 [ permalink ] | Read more »
Pinball Planet Pro (Games)
Pinball Planet Pro 1.02 Device: iOS Universal Category: Games Price: $2.99, Version: 1.02 (iTunes) Description: - Our missionWe've always loved to play pinball games but we noticed most modern pinball games are simulators for the... | Read more »
Ultrakam 4k. The Professional Camera App...
Ultrakam 4k. The Professional Camera App. 3.0 Device: iOS Universal Category: Photography Price: $9.99, Version: 3.0 (iTunes) Description: In March 2014, Ultrakam brought Film Resolution for iPhone for the first time ever and now is... | Read more »
Email+ (Business)
Email+ 1.0 Device: iOS Universal Category: Business Price: $2.99, Version: 1.0 (iTunes) Description: Send email, fast! | Read more »
Mayor it up in SimCity BuildIt, Out Now
Mayor it up in SimCity BuildIt, Out Now Posted by Jessica Fisher on December 16th, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »

Price Scanner via MacPrices.net

Holiday sales continue: MacBook Pros for up t...
 B&H Photo has new MacBook Pros on sale for up to $300 off MSRP as part of their Holiday pricing. Shipping is free, and B&H charges NY sales tax only: - 15″ 2.2GHz Retina MacBook Pro: $1699... Read more
Google Search App For iOS Gets A Major Makeov...
Google has given iOS users an early Christmas present with a substantial update of it’s not-very-often-upgraded Google Search app. Google Search has been my go-to tool for Web searches since it was... Read more
ShopKeep Apple Pay And Chip Card Reader Avail...
ShopKeep, a cloud-based technology provider to more than 10,000 small business owners to manage retail shops and restaurants with iPads, has released its new Apple Pay and chip card reader. This... Read more
Holiday sale! 27-inch 5K iMac for $2299, save...
 B&H Photo has the 27″ 3.5GHz 5K iMac in stock today and on sale for $2299 including free shipping plus NY sales tax only. Their price is $200 off MSRP, and it’s the lowest price available for... Read more
Holiday Sale! 3.7GHz Quad Core Mac Pro availa...
 B&H Photo has the 3.7GHz Quad Core Mac Pro on sale for $2599 including free shipping plus NY sales tax only. Their price is $400 off MSRP, and it’s the lowest price for this model from any... Read more
iPhone 6 Number 3 Canadian Google Search Of 2...
CTVNews.ca reports that Apple’s iPhone 6 was the third highest-trending Google Canada search topic of 2014, exceeded only by Robin Williams largely after his death by suicide in August, and the FIFA... Read more
New iPad mini 3 Counter-Top & Wall Mount...
newMacgadgets has announced new secure all-acrylic displays for the iPad mini 3 (also works fine with the mini 2, last year’s iPad mini With Retina Display, and the original iPad mini). The new iPad... Read more
Holiday sales continue, MacBook Airs for up t...
B&H Photo has 2014 MacBook Airs on sale for up to $120 off MSRP, for a limited time, for the Thanksgiving/Christmas Holiday shopping season. Shipping is free, and B&H charges NY sales tax... Read more
B&H lowers price on 27-inch 3.2GHz iMac t...
B&H Photo has lowered their price on the 27″ 3.2GHz iMac, now on sale for $1629 including free shipping plus NY sales tax only. Their price is $170 off MSRP, and it’s the lowest price for this... Read more
15-inch 2.0GHz Retina MacBook Pro available f...
B&H Photo has lowered their price on leftover 2013 15″ 2.0GHz Retina MacBook Pros to $1499 including free shipping plus NY sales tax only. Their price is $500 off original MSRP. 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* 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* Retail - Multiple Positions (US) - A...
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 (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
Project Manager / Business Analyst, WW *Appl...
…a senior project manager / business analyst to work within our Worldwide Apple Fulfillment Operations and the Business Process Re-engineering team. This role will work Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.