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. *

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

iTubeDownloader 6.5.13 - Easily download...
iTubeDownloader is a powerful-yet-simple YouTube downloader for the masses. Because it contains a proprietary browser, you can browse YouTube like you normally would. When you see something you want... Read more
FileZilla 3.47.0 - Fast and reliable FTP...
FileZilla (ported from Windows) is a fast and reliable FTP client and server with lots of useful features and an intuitive interface. Version 3.47.0: Fixed regression loading advanced site... Read more
Transmit 5.6.3 - Excellent FTP/SFTP clie...
Transmit is an excellent FTP (file transfer protocol), SFTP, S3 (Amazon.com file hosting) and iDisk/WebDAV client that allows you to upload, download, and delete files over the internet. With the... Read more
Doomsday 2.2.2 - Play classic Doom on mo...
id Software's Doom pioneered the modern first-person shooter genre. Released in 1993, it was a quantum leap in game engine technology with fluid and - at the time - incredibly realistic 3D graphics.... Read more
Ableton Live 10.1.9 - Record music using...
Ableton Live lets you create and record music on your Mac. Use digital instruments, pre-recorded sounds, and sampled loops to arrange, produce, and perform your music like never before. Ableton Live... Read more
Maintenance 2.6.5 - System maintenance u...
Maintenance is a system maintenance and cleaning utility. It allows you to run miscellaneous tasks of system maintenance: Check the the structure of the disk Repair permissions Run periodic scripts... Read more
Adobe Photoshop 21.1.0 - Professional im...
You can download Photoshop for Mac as a part of Creative Cloud for only $20.99/month (or $9.99/month if you have purchased an earlier software version). Adobe Photoshop remains the gold standard in... Read more
Adobe Lightroom Classic 9.2 - Import, de...
You can download Lightroom for Mac as a part of Creative Cloud for only $9.99/month with Photoshop, included as part of the photography package. The latest version of Lightroom gives you all of the... Read more
Adobe InCopy 15.0.1 - Create streamlined...
InCopy is available as part of Adobe Creative Cloud for $52.99/month (or $4.99/month for InCopy app only). Adobe InCopy, ideal for large team projects involving both written copy and design work,... Read more
Adobe Illustrator 24.0.3 - Professional...
You can download Adobe Illustrator for Mac as a part of Creative Cloud for only $20.99/month (or $9.99/month if you have also purchased an earlier software version). Adobe Illustrator for Mac is the... Read more

Latest Forum Discussions

See All

Mobile Games Starter Kit
Over here at 148Apps, we regularly dive deep into the latest and greatest mobile games hitting the App Store, but that’s not always what people are looking for when searching for a new mobile game. Some folks just want to dip their toes into... | Read more »
Unresolved is a hard-hitting narrative a...
Ghofran Akil's Unresolved in an upcoming text-based adventure game that sees you playing as a mother attempting to find her disappeared husband during the Lebanese Civil War. [Read more] | Read more »
Marvel Strike Force introduces new brawl...
FoxNext's squad-based RPG Marvel Strike Force is set to receive some fresh characters from the X-Men and Iron Man series. They'll arrive as part of the game's latest update, which follows a sizable spending boycott on the title due to complaints... | Read more »
Speed Dating for Ghosts is a narrative a...
Speed Dating for Ghosts originally released on Steam back 2018, since then it has received honourable mentions for narrative during the Independent Games Festival. Now it's made its way over to iOS devices where it's available as a premium title... | Read more »
Fast-paced multiplayer title Tennis Star...
Tennis Stars: Ultimate Clash is the latest free-to-play tennis title to hit iOS and Android. It's said to be a fairly casual experience, offering easy-to-learn controls and fast-paced, mobile-friendly matches. [Read more] | Read more »
Super Mecha Champions' latest updat...
Super Mecha Champions' latest update sees the addition of a brand new character called R.E.D. Alongside that, there's news about the current season and a series of Emojis that have been added to the game. [Read more] | Read more »
Apple Arcade: Ranked - Top 50 [Updated 2...
In case you missed it, I am on a quest to rank every Apple Arcade game there is. [Read more] | Read more »
Apple Arcade: Ranked - 51+ [Updated 2.19...
This is part 2 of our Apple Arcade Ranking list. To see part 1, go here. To skip to part 3, click here. 51. Mini Motorways Description: [Read more] | Read more »
Isle Escape: The House is an upcoming pu...
Isle Escape: The House is an upcoming puzzle game from Simeon Angelov that's intended to serve as an introduction to a saga they're planning on releasing in an episodic fashion. The first chapter is set to release for both iOS and Android on 29th... | Read more »
Company of Heroes, the classic RTS, is n...
Feral Interactive has finally released their highly anticipated iOS version of the strategy classic Company of Heroes. It's available now for iPad as a premium title and has had various tweaks to ensure that it's optimised for touch controls. [... | Read more »

Price Scanner via MacPrices.net

Verizon offers free iPhone 7 to customers ope...
Verizon is offering a free 32GB iPhone 7 for new or existing customers who open a new line of service, no trade-in required. Cost of the phone is credited to your account monthly over 24 months. The... Read more
Sale! 10.5″ 256GB WiFi iPad Air for $549, $10...
Amazon has new 10.5″ 256GB WiFi iPad Airs, in Space Gray, on sale today for $549 shipped. Their price is $100 off Apple’s MSRP for this model, and it’s the cheapest price available from any Apple... Read more
Back on sale! Apple’s new Mac Pro for $5499,...
B&H Photo has the base 2019 Mac Pro (3.5GHz 8-Core Xeon, 32GB RAM, 256GB SSD) in stock today and on sale for $5499 including free overnight delivery to many addresses in the US. Their price is $... Read more
B&H offers $100 discount on base 13″ 1.4G...
B&H Photo has new 2019 13″ 1.4GHz MacBook Pros on sale for $100 off Apple’s MSRP today with prices starting at $1199. Overnight shipping is free to many addresses in the US. These are the same... Read more
Apple continues to offer Certified Refurbishe...
Apple has Certified Refurbished iPhone XS models available for up to $350 off MSRP, with prices starting at $699. Each iPhone is unlocked and comes with Apple’s standard one-year warranty and a new... Read more
Apple AirPods are on sale for $30 off today
Amazon has new 2019 Apple AirPods (non-Pro models) on sale today for $30 off MSRP, starting at $129. Shipping is free: – AirPods with Wireless Charging Case: $169 $30 off MSRP – AirPods with Charging... Read more
27″ 3.7GHz 6-Core 5K iMac on sale for $2099,...
B&H Photo has the 2019 27″ 3.7GHz 6-Core 5K iMac in stock today and on sale for $200 off Apple’s MSRP. Overnight shipping is free to many locations in the US: – 27″ 3.7GHz 6-Core 5K iMac: $2099 $... Read more
Save up to $250 on a 12.9″ iPad Pros with the...
Apple has Certified Refurbished 12.9″ iPad Pros available on their online store for up to $250 off the cost of new models. Prices start at $849. Each iPad comes with a standard Apple one-year... Read more
Save up to $220 on 11″ iPad Pros with these r...
Apple has Certified Refurbished 11″ iPad Pros available on their online store for up to $220 off the cost of new models. Prices start at $679. Each iPad comes with a standard Apple one-year warranty... Read more
8-Core 27″ iMac Pro available for $4249, Cert...
Apple has Certified Refurbished 27″ 3.2GHz 8-Core iMac Pros available for $4249 including free shipping. Their price is $750 off the cost of new models. A standard Apple one-year warranty is included... Read more

Jobs Board

Medical Assistant - *Apple* Valley Clinic -...
…professional, quality care to patients in the ambulatory setting at the M Health Fairview Apple Valley Clinic, located in Apple Valley, MN. Join the **M Health Read more
Windows/ *Apple* Technical Support Engineer...
Windows/ Apple Technical Support Engineer McLean , VA , US Apply + Be you + Be Booz Allen + Be empowered + Learn More Job Description Location: McLean, VA, US Job Read more
Medical Assistant - *Apple* Valley Clinic -...
…professional, quality care to patients in the ambulatory setting at the M Health Fairview Apple Valley Clinic, located in Apple Valley, MN. Join the **M Health Read more
Geek Squad *Apple* Consultation Professiona...
**762475BR** **Job Title:** Geek Squad Apple Consultation Professional **Job Category:** Store Associates **Store NUmber or Department:** 001423-San Jose-Store **Job Read more
Medical Assistant - *Apple* Valley Clinic -...
…professional, quality care to patients in the ambulatory setting at the M Health Fairview Apple Valley Clinic, located in Apple Valley, MN. Join the **M Health Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.