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

Capto 1.2.9 - $29.99
Capto (was Voila) is an easy-to-use app that takes capturing, recording, video and image editing to the next level. With an intelligent file manager and quick sharing options, Capto is perfect for... Read more
Opera 51.0.2830.40 - High-performance We...
Opera is a fast and secure browser trusted by millions of users. With the intuitive interface, Speed Dial and visual bookmarks for organizing favorite sites, news feature with fresh, relevant content... Read more
GarageSale 7.0.13 - Create outstanding e...
GarageSale is a slick, full-featured client application for the eBay online auction system. Create and manage your auctions with ease. With GarageSale, you can create, edit, track, and manage... Read more
1Password 6.8.7 - Powerful password mana...
1Password is a password manager that uniquely brings you both security and convenience. It is the only program that provides anti-phishing protection and goes beyond password management by adding Web... Read more
Evernote 7.0.1 - Create searchable notes...
Evernote allows you to easily capture information in any environment using whatever device or platform you find most convenient, and makes this information accessible and searchable at anytime, from... Read more
MacUpdate Desktop 6.2.0 - $20.00
MacUpdate Desktop brings seamless 1-click app installs and version updates to your Mac. With a free MacUpdate account and MacUpdate Desktop 6, Mac users can now install almost any Mac app on... Read more
HoudahSpot 4.3.5 - Advanced file-search...
HoudahSpot is a versatile desktop search tool. Use HoudahSpot to locate hard-to-find files and keep frequently used files within reach. HoudahSpot will immediately feel familiar. It works just the... Read more
EtreCheck 4.0.4 - For troubleshooting yo...
EtreCheck is an app that displays the important details of your system configuration and allow you to copy that information to the Clipboard. It is meant to be used with Apple Support Communities to... Read more
WhatsApp 0.2.8361 - Desktop client for W...
WhatsApp is the desktop client for WhatsApp Messenger, a cross-platform mobile messaging app which allows you to exchange messages without having to pay for SMS. WhatsApp Messenger is available for... Read more
iClock 4.2 - Customize your menubar cloc...
iClock is a menu-bar replacement for Apple's default clock but with 100x features. Have your Apple or Google calendar in the menubar. Have the day, date, and time in different fonts and colors in the... Read more

Latest Forum Discussions

See All

The best games like Florence
Florence is a great little game about relationships that we absolutely adored. The only problem with it is it's over a little too soon. If you want some other games with some emotional range like Florence, check out these suggestions: [Read more] | Read more »
Angry Birds Champions adds cash prizes t...
Collaborating with developer Rovio Entertainment, GSN Games has released a twist on the Angry Birds formula. Angry Birds Champions features the same bird-flinging gameplay, but now you can catapult Red and co for cash. | Read more »
Around the Empire: What have you missed...
148Apps is part of a family. A big family of sites that make sure you're always up to date with all the portable gaming news. Just like a real family, I guess. I don't know, my mum never told me anything about Candy Crush to be fair. [Read more] | Read more »
The Battle of Polytopia Guide - Tips for...
The addition of multiplayer to The Battle of Polytopia has catapulted the game from a fun enough time waster to a fully-fledged 4X experience on your phone. We've been playing quite a few matches over the past week or so, and we've put together a... | Read more »
All the best games on sale for iPhone an...
Hi there, and welcome to our round up of all the best games that are on sale for iOS at the moment. It's not a vintage week in terms of numbers, but I'm pretty sure that every single one of these is worth picking up if you haven't already played... | Read more »
Disc Drivin' 2 Guide - Tips for the...
We're all still playing quite a bit of Disc Drivin' 2 over here at 148Apps, and we've gotten pretty good at it. Now that we've spent some more time with the game and unlocked more powerups, check out some of these more advanced tips: | Read more »
Alto's Odyssey Guide - How to Tackl...
Alto’s Odyssey is a completely stunning and serene runner, but it can also be a bit tricky. Check out these to try and keep your cool while playing this endless runner: Don’t focus too much on tasks [Read more] | Read more »
Here's everything you need to know...
Alto's Odyssey is a really, really good game. If you don't believe me, you should definitely check out our review by clicking this link right here. It takes the ideas from the original Alto's Adventure, then subtly builds on them, creating... | Read more »
Alto's Odyssey (Games)
Alto's Odyssey 1.0.1 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.1 (iTunes) Description: Just beyond the horizon sits a majestic desert, vast and unexplored. Join Alto and his friends and set off on an endless... | Read more »
Vainglory 5v5: Everything you need to kn...
Vainglory just got bigger. [Read more] | Read more »

Price Scanner via MacPrices.net

Apple AirPods in stock today for $159, free s...
Adorama reports stock of Apple AirPods today for $159 including free shipping, plus pay no sales tax outside of NY & NJ. See our Apple AirPod Price Tracker for the latest prices and stock status... Read more
Saturday Sale: Amazon offers 12″ 1.3GHz MacBo...
Amazon has Silver and Gold 2017 12″ 1.3GHz Retina MacBooks on sale for $250 off MSRP. Shipping is free: – 12″ 1.3GHz Silver MacBook: $1349.99 $250 off MSRP – 12″ 1.3GHz Gold MacBook: $1349.99 $250... Read more
Use your Apple Education discount and save up...
Purchase a new Mac using Apple’s Education discount, and take up to $400 off MSRP. All teachers, students, and staff of any educational institution with a .edu email address qualify for the discount... Read more
Apple Canada offers 2017 21″ and 27″ iMacs fo...
 Canadian shoppers can save up to $470 on the purchase of a 2017 current-generation 21″ or 27″ iMac with Certified Refurbished models at Apple Canada. Apple’s refurbished prices are the lowest... Read more
9″ iPads available online at Walmart for $50...
Walmart has 9.7″ Apple iPads on sale for $50 off MSRP for a limited time. Sale prices are for online orders only, in-store prices may vary: – 9″ 32GB iPad: $279.99 $50 off – 9″ 128GB iPad: $379.99 $... Read more
15″ Apple MacBook Pros, Certified Refurbished...
Save $360-$420 on the purchase of a 2017 15″ MacBook Pro with Certified Refurbished models at Apple. Apple’s refurbished prices are the lowest available for each model from any reseller. An standard... Read more
Amazon restocks MacBook Pros with models avai...
Amazon has restocked 15″ and 13″ Apple MacBook Pros with models on sale for up to $251 off MSRP. Shipping is free. Note that stock of some Macs may come and go (and some sell out quickly), so check... Read more
Lowest price of the year: 15″ 2.8GHz Apple Ma...
Amazon has the 2017 Space Gray 15″ 2.8GHz MacBook Pro on sale today for $251 off MSRP. Shipping is free: – 15″ 2.8GHz Touch Bar MacBook Pro Space Gray (MPTR2LL/A): $2148, $251 off MSRP Their price is... Read more
Apple restocks full line of Certified Refurbi...
Apple has restocked a full line of Apple Certified Refurbished 2017 13″ MacBook Pros for $200-$300 off MSRP. A standard Apple one-year warranty is included with each MacBook, and shipping is free.... Read more
Lowest sale price available for 13″ 1.8GHz Ma...
Focus Camera has the 2017 13″ 1.8GHz/128GB Apple MacBook Air on sale today for $829 including free shipping. Their price is $170 off MSRP, and it’s the lowest price available for a current 13″... Read more

Jobs Board

*Apple* Media Products Commerce Engineering...
# Apple Media Products Commerce Engineering Manager Job Number: 56207285 Santa Clara Valley, California, United States Posted: 26-Jan-2018 Weekly Hours: 40.00 **Job Read more
Digital Platforms Lead, Today at *Apple* -...
# Digital Platforms Lead, Today at Apple Job Number: 56178747 Santa Clara Valley, California, United States Posted: 23-Feb-2018 Weekly Hours: 40.00 **Job Summary** 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* 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
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.