TweetFollow Us on Twitter

Newton Q&A final rev

Newton Q & A: Ask the Llama

Q I'm trying to remove indexes that I've added to the names soup. But the code to do it is kind of ugly. First I have to go through all the indexes to see if my index is in the soup. Then if I find the index, I can remove it. Is there an easier way?

A Yes, there's an easier way. Remember that a call to RemoveIndex will throw an exception if it's passed an invalid index. You can wrap your code in an exception handler and prevent the invalid index exception from leaving your code:

ExceptionBasedRemoveIndex := func(theSlotsym, theSoupName) begin local theSoup; foreach store in GetStores() do begin theSoup := store:GetSoup(theSoupName); if theSoup then try theSoup:removeIndex(theSlotsym); onexception |evt.ex.fr.store| do if CurrentException().error <> -48013 then ReThrow(); end; end

This function will remove a particular index (specified by theSlotsym) from a particular soup (specified by theSoupName) on all currently mounted stores. If the index exists, it will be removed; otherwise, the exception thrown for trying to remove an invalid index will be caught and ignored. If a different exception occurs, it will be rethrown so that other exception handlers or the system can deal with the exception.

Q I'm writing a utility that is an auto part. My utility needs preferences, but there's no application to add preferences to. Where should I put my preferences?

A The guidelines for preferences are simple: * For any addition that has an icon in the extras drawer, the preferences should be part of that application. Use the info button to access them. * For something that has no icon in the extras drawer, add your preferences to the system preferences roll.

See the sample "Preefer Madness" on this issue's CD for more information.

Q When text gets pasted into my paragraph view, that text is highlighted. I want to be able to detect when this happens and then be able to unselect the text. How do I do that? 

A When the text gets added, the viewChangedScript will get called with the slot parameter set to 'text. You can use the SetHilite message to unhighlight the text. However, the viewChangedScript will get called before the underlying implementation of the paragraph view has been changed. This means you need to call SetHilite in a deferred action.

Q I'm writing a specialized application for a corporate customer. One of the requirements is that the application launch when the Newton is turned on (a "turnkey" application). Is there a way to do this with the Newton? 

A You can use the installScript of your application to add a deferred action that opens your application:

constant kAppSymbol := '|autoLaunch:PIEDTS|; installScript := func(partFrame) begin AddDeferredAction(func() GetRoot().(kAppSymbol):Open(), []); end;

This will launch your application whenever the Newton is restarted or a card containing your application is inserted. Note that if the application is closed before the Newton is restarted again, the application will not relaunch. Nor will the user be prevented from accessing other features of the Newton such as Names, Dates, or Extras Drawer; that's a much harder problem.

Q I've been trying to use the protoRoll and protoRollItem to create a roll browser of my own. Everything works fine until I scroll. For a couple of these items I need to tap the down arrow twice for it to go to the next roll item. I see the scrolling view effect, but it just scrolls to itself.

The height slot in each of the roll items has the same value as the height in their viewBounds slot. If I move the roll items around when they're added to the protoRoll (dynamically from my own protos), they work fine. How can I fix this? 

A The problem is that one of the protoRollItems in the items array is larger than the protoRoll. If you make the roll browser larger than the largest roll item, all will work fine; otherwise, you have to scroll the roll item twice to move to the next roll item.

Also, since you imply that the entire large roll item is visible, I assume that the protoRoll has vClipping turned off. If you'd had clipping on, you would probably have noticed that the individual roll item was too large.

Q I'm having some problems with margins when I'm faxing. A fax without a cover page has different margins than a printed page. The actual viewBounds is the same, but the margins of the fax are different from the viewBounds.

Also, a fax with a cover page has even different margins. The viewBounds is different, too (20 pixels shorter in height), but that's OK. The problem is that the actual margins when faxed are different from those specified by the viewBounds slot. Is this a known problem? 

A Faxes with a cover page have a header line at the top of the fax which takes up those mysterious 20 pixels. In fact, it might be a bug that faxes without a cover page omit this header, but perhaps the only bug is not documenting that protoPrintFormat (which provides the cover page) also adds that header.

The way to find the correct page bounds is to set the viewBounds of your base print view to that of the parent. The base print view is usually a clView that is a child of a print layout. You can use the following code in the viewSetupFormScript of your base print view to set your bounds to those of your parent: viewBounds := :Parent():LocalBox();

Q I've got an auto part that installs a template for the formulas roll. On the roll item I've got a protoLabelInputLine for data entry, and a button that I want to use to clear the input line. My buttonClickScript is very simple:

buttonClickScript := func() begin SetValue(myInputLine.entryLine, 'text, ""); end;

The first time the button is tapped, the input line gets cleared OK; after that it never seems to work, no matter how I code it. Can you help? 

A This is a very subtle problem. The answer will be revealed in stages, so that you too can experience the "Aha!"

Observation 1: When you edit the text in any clParagraphView, no new strings are generated. The existing string is destructively modified (excluding the usual _proto copying, of course).

Observation 2: During the compile cycle, the Newton Toolkit will turn all your strings into constants. Contrast this to using braces to construct a frame. As an illustration, assume you have these three methods:

Method1 := func() begin return {slot1: "also string"}; end;

Method2 := func() begin return '{slot2: "also also string"}; end;

Method3 := func() begin return "a string"; end;

The braces specify a frame constructor. Each time you call Method1 it will return a reference to a newly allocated frame, though not different contents. For example, when the following is executed

myVar := call Method1() with ();

here's what you get in memory:

[IMAGE Newton_Q&A_final_html1.GIF]

On the other hand, Method2 quotes the frame, which makes it a quoted constant. In other words, each time you call Method2 it will return a reference to the same frame. And Method3 does something else altogether: In the Newton Toolkit, a string is treated like a quoted frame (or array). It's a constant object, so each time you call Method3 it will return a reference to the same string. Note that this means that in both Method1 and Method2 the slot in each frame will reference the same string. Diagrams that show what happens in memory when each of these three methods is executed are provided on this issue's CD along with this Q & A column.

Observation 3: When you call SetValue, you're actually copying the reference to the empty string from your buttonClickScript into the text slot of the entry line. You might think this would cause an error, because the string constant can't be modified. But clParagraphViews are smart: if the string can't be modified (that is, if it's read-only), a copy is made.

Observation 4: I checked in the inspector, and your buttonClickScript is not read- only. This means that the string constant "" in that script is also not read-only.

Observation 5: To prevent the grip of death on a card, you would need to call EnsureInternal on your formula roll entry. This effectively makes a copy of the entire template, including constants, in the NewtonScript heap. The following illustration contrasts a Clone with a DeepClone (which is what EnsureInternal uses). Note that the DeepClone creates a new read/write copy of the string.
















Conclusion: You press the Clear Data button once. This sets the reference of the input line string to point to the string constant in your buttonClickScript. Since the string constant is no longer read-only, changing the input line string destructively modifies the string constant. You may think that this would lead to a bus error or worse, but thanks to NewtonScript, it works as it should. The next time you press the Clear Data button, the input line string reference gets replaced with a reference to the now modified string constant.

[IMAGE Newton_Q_A_final_html2.GIF]

The solution is to change the SetValue call to

SetValue(dataItem.entryLine, 'text, Clone(""));

This will make a copy of the string constant and return a reference to the copy.

Q Just recently I came into possession of a sword. It was handed to me by a lady in a lake whose arm was clad in the finest shimmering samite. I figure with this sign of divine providence I should be able to wield supreme executive power. What do you think? 

A Fortunately, strange women in ponds have not been used as the basis for a system of government since the Dark Ages. These days supreme executive power derives from a mandate from the masses, not from a farcical aquatic ceremony. If I claimed to be President just because some aquatic gymnast threw a sword at me, I'd be locked up for sure.

The llama is the unofficial mascot of the Developer Technical Support group in Apple's Personal Interactive Electronics (PIE) division. Send your Newton-related questions to NewtonMail DRLLAMA or AppleLink DR.LLAMA. The first time we use a question from you, we'll send you a T-shirt. *

Thanks to Don Gummow and our Newton Partners for the questions used in this column, and to jXopher Bell, Bob Ebert, Mike Engber, Kent Sandvik, Jim Schram, and Maurice Sharp for the answers.

*Have more questions? Need more answers? Take a look at PIE Developer Info on AppleLink. *

 
AAPL
$100.58
Apple Inc.
+0.01
MSFT
$45.22
Microsoft Corpora
+0.27
GOOG
$583.37
Google Inc.
-1.12

MacTech Search:
Community Search:

Software Updates via MacUpdate

Pages 5.2.2 - Apple's word processo...
Apple Pages is a powerful word processor that gives you everything you need to create documents that look beautiful. And read beautifully. It lets you work seamlessly between Mac and iOS devices. And... Read more
Quicken 2015 2.0.1 - Complete personal f...
The new Quicken 2015 helps you manage all your personal finances in one place, so you can see where you're spending and where you can save. Quicken automatically categorizes your financial... Read more
CleanMyMac 2.2.7 - Delete files that was...
CleanMyMac makes space for the things you love. Sporting a range of ingenious new features, CleanMyMac 2 lets you safely and intelligently scan and clean your entire system, delete large, unused... Read more
MacFamilyTree 7.2.4 - Create and explore...
MacFamilyTree gives genealogy a facelift: it's modern, interactive, incredibly fast, and easy to use. We're convinced that generations of chroniclers would have loved to trade in their genealogy... Read more
Videobox 4.1.1 - Download Flash video th...
Videobox allows you to quickly and easily download Flash video from most all of the popular video sites on the internet. Videobox will convert the video into a native Quicktime format so it's ready... Read more
Web Snapper 3.3.5 - 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... Read more
Picasa 3.9.138 - Organize, edit, and sha...
Picasa and Picasa Web Albums allows you to organize, edit, and upload your photos to the Web from your computer in quick, simple steps. Arrange your photos into folders and albums and erase their... Read more
Tidy Up 3.0.15.0 - Find duplicate files...
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
Parallels Desktop 10.0 - Run Windows app...
Parallels Desktop is simply the world's bestselling, top-rated, and most trusted solution for running Windows applications on your Mac. With Parallels Desktop for Mac, you can seamlessly run both... Read more
Apple Final Cut Pro X 10.1.3 - Professio...
Apple Final Cut Pro X is a professional video editing solution.Completely redesigned from the ground up, Final Cut Pro adds extraordinary speed, quality, and flexibility to every part of the post-... Read more

Latest Forum Discussions

See All

Pentumble (Games)
Pentumble 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: *** Special Launch Price! 33% Off! *** Pentumble combines the joy of a free-flowing platformer with beautiful graphics and levels... | Read more »
DotEmu Summer Sale Cuts Several Games’ P...
DotEmu Summer Sale Cuts Several Games’ Prices to $0.99 Posted by Ellis Spice on August 21st, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
King Announces its Newest “Saga” – Diamo...
King Announces its Newest “Saga” – Diamond Digger Saga Posted by Jessica Fisher on August 21st, 2014 [ permalink ] Diamond Digger Saga, by King Digital Entertainment, promises to be another addictive, adorable game in the “Saga” | Read more »
Spacetime Studios’ Greg Mueller Tells Al...
| Read more »
TourStar Review
TourStar Review By Rob Thomas on August 21st, 2014 Our Rating: :: BORING TOURINGUniversal App - Designed for iPhone and iPad When The Ramones sang “Touring, touring/It’s never boring,” they clearly weren’t referring to TourStar.... | Read more »
Track Your Pregnancy with Glow Nurture
Track Your Pregnancy with Glow Nurture Posted by Jessica Fisher on August 21st, 2014 [ permalink ] iPhone App - Designed for the iPhone, compatible with the iPad | Read more »
Outcast Odyssey – An Interview with the...
At this year’s San Diego Comic-Con, fans got the chance to meet and mingle with several of the artists behind Magic Pixel Games and Namco Bandai’s upcoming card battler, Outcast Odyssey. Considering many of these artists have worked on comics in the... | Read more »
BoxPop Review
BoxPop Review By Jennifer Allen on August 21st, 2014 Our Rating: :: UNTAXING PUZZLESUniversal App - Designed for iPhone and iPad Move from tile to tile to clear the board in this slightly too simple and easy puzzle game.   | Read more »
Breakdown Buddy Review
Breakdown Buddy Review By Jennifer Allen on August 21st, 2014 Our Rating: :: FLAWED CONCEPTiPhone App - Designed for the iPhone, compatible with the iPad There’s a good idea here, but Breakdown Buddy isn’t as useful as it tries to... | Read more »
jamstik, the Guitar You Can Take Everywh...
jamstik, the Guitar You Can Take Everywhere, is Now Available for Purchase Posted by Jessica Fisher on August 21st, 2014 [ permalink ] Zivix has announced that their guitar-in-your-pocket, | Read more »

Price Scanner via MacPrices.net

Pro.Calendar – New Productivity App for iPad...
Austin, Texas based mobile business and productivity app developer LightArrow, Inc. has announced Pro.Calendar, a powerful and intuitive calendar app with eight versatile calendar options including... Read more
SanDisk Ultra II SSD — Supercharge Your Syste...
SanDisk Corporation has announced the new SanDisk Ultra II SSD with enhanced SSD Dashboard. The new drive is designed to deliver a cost-effective and easy upgrade solution for PC owners looking to... Read more
Samsung and Barnes & Noble Introduce New...
Samsung Electronics America and NOOK Media, a subsidiary of Barnes & Noble, Inc. have announced the introduction of the new Samsung Galaxy Tab 4 NOOK, a 7-inch tablet combining Samsung’s leading... Read more
21-inch iMacs on sale for up to $150 off MSRP
B&H Photo has 21″ iMacs on sale for up to $150 off MSRP including free shipping plus NY sales tax only. B&H will also include a free copy of Parallels Desktop software: - 21″ 2.7GHz iMac: $... Read more
27-inch 3.2GHz iMac on sale for $1698, save $...
Abt has the 27″ 3.2GHz iMac on sale for $1698 including free shipping. Their price is $101 off MSRP. Read more
Mac Backup Guru 2.0 Drive Backup/Cloneing Uti...
Mac Backup Guru developer MacDaddy has released Mac Backup Guru 2.0, offering new and enhanced advanced features, such as bootable backups, synchronised volumes and folders, and a Snapshot mode that... Read more
Operate GE’s New Free-Standing KItchen Range...
Think you accidentally left the oven on? Switch it off while on the go. The new free-standing Profile™ Series gas and electric ranges are GE’s second cooking appliances, following their wall oven, to... Read more
Parallels Announces Parallels Desktop 10 for...
The no. 1-selling software for running Windows applications on a Mac becomes an even easier choice for millions of consumers and IT professionals worldwide with the launch of the most powerful... Read more
Apple now offering certified refurbished 2014...
 The Apple Store is now offering Apple Certified Refurbished 2014 MacBook Airs for up to $180 off the cost of new models. An Apple one-year warranty is included with each MacBook, and shipping is... Read more
Best Buy’s College Student Deals: $100 off Ma...
Take an additional $100 off all MacBooks and iMacs, $50 off iPad Airs and iPad minis, at Best Buy Online with their College Students Deals Savings, valid through September 6th. Anyone with a valid .... 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
Position Opening at *Apple* - Apple (United...
**Job Summary** As more and more people discover Apple , they visit our stores seeking ways to incorporate our products into their lives. It's your job, as a Store Read more
Position Opening at *Apple* - Apple (United...
…Summary** As a Specialist, you help create the energy and excitement around Apple products, providing the right solutions and getting products into customers' hands. You Read more
Project Manager, *Apple* Financial Services...
**Job Summary** Apple Financial Services (AFS) offers consumers, businesses and educational institutions ways to finance Apple purchases. We work with national and Read more
*Apple* Solutions Consultant (ASC)- Retail S...
**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.