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• Legacy application creates dialogs in non-ui thread.

  - by Frater

  I've been working support for a while on a legacy application and I've noticed a bit of a problem. The system is an incredibly complex client/server with standard and custom frameworks. One of the custom frameworks built into the application involves validating workflow actions. It finds potential errors, separates them into warnings and errors, and passes the results back to the client. The main difference between warnings and errors is that warnings ask the user if they wish to ignore the error. The issue I have is that the dialog for this prompt is created on a non-ui thread, and thus we get cross-threading issues when the dialog is shown. I have attempted to invoke the showing of the dialog, however this fails because the window handle has not been created. (InvokeRequired returns false, which I assume in this case means it cannot find a decent handle in its parent tree, rather than that it doesn't require it.) Does anyone have any suggestions for how I can create this dialog and get the UI thread to set it up and call it?

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• Stop SQL returning the same result twice in a JOIN

  - by nbs189

  I have joined together several tables to get data i want but since I am new to SQL i can't figure out how to stop data being returned more than once. her's the SQL statement; SELECT T.url, T.ID, S.status, S.ID, E.action, E.ID, E.timestamp FROM tracks T, status S, events E WHERE S.ID AND T.ID = E.ID ORDER BY E.timestamp DESC The data that is returned is something like this; +----------------------------------------------------------------+ | URL | ID | Status | ID | action | ID | timestamp | +----------------------------------------------------------------+ | T.1 | 4 | hello | 4 | has uploaded a track | 4 | time | | T.2 | 3 | bye | 3 | has some news | 3 | time | | t.1 | 4 | more | 4 | has some news | 4 | time | +----------------------------------------------------------------+ That's a very basic example but does outline what happens. If you look at the third row the URL is repeated when there is a different status. This is what I want to happen; +-------------------------------------------------------+ | URL or Status | ID | action | timestamp | +-------------------------------------------------------+ | T.1 | 4 | has uploaded a track | time | | hello | 3 | has some news | time | | bye | 4 | has some news | time | +-------------------------------------------------------+ Please notice that the the url (in this case the mock one is T.1) is shown when the action is has uploaded a track. This is very important. The action in the events table is inserted on trigger of a status or track insert. If a new track is inserted the action is 'has uploaded a track' and you guess what it is for a status. The ID and timestamp is also inserted into the events table at this point. Note: There are more tables that go into the query, 3 more in fact, but I have left them out for simplicity.

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• What should I use to increase performance. View/Query/Temporary Table

  - by Shantanu Gupta

  I want to know the performance of using Views, Temp Tables and Direct Queries Usage in a Stored Procedure. I have a table that gets created every time when a trigger gets fired. I know this trigger will be fired very rare and only once at the time of setup. Now I have to use that created table from triggers at many places for fetching data and I confirms it that no one make any changes in that table. i.e ReadOnly Table. I have to use this tables data along with multiple tables to join and fetch result for further queries say select * from triggertable By Using temp table select ... into #tx from triggertable join t2 join t3 and so on select a,b, c from #tx --do something select d,e,f from #tx ---do somethign --and so on --around 6-7 queries in a row in a stored procedure. By Using Views create view viewname ( select ... from triggertable join t2 join t3 and so on ) select a,b, c from viewname --do something select d,e,f from viewname ---do somethign --and so on --around 6-7 queries in a row in a stored procedure. This View can be used in other places as well. So I will be creating at database rather than at sp By Using Direct Query select a,b, c from select ... into #tx from triggertable join t2 join t3 join ... --do something select a,b, c from select ... into #tx from triggertable join t2 join t3 join ... --do something . . --and so on --around 6-7 queries in a row in a stored procedure. Now I can create a view/temporary table/ directly query usage in all upcoming queries. What would be the best to use in this case.

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• Generate unique ID from multiple values with fault tolerance

  - by ojreadmore

  Given some values, I'd like to make a (pretty darn) unique result. $unique1 = generate(array('ab034', '981kja7261', '381jkfa0', 'vzcvqdx2993883i3ifja8', '0plnmjfys')); //now $unique1 == "sqef3452y"; I also need something that's pretty close to return the same result. In this case, 20% of the values is missing. $unique2 = generate(array('ab034', '981kja7261', '381jkfa0', 'vzcvqdx2993883i3ifja8')); //also $unique2 == "sqef3452y"; I'm not sure where to begin with such an algorithm but I have some assumptions. I assume that the more values given, the more accurate the resulting ID – in other words, using 20 values is better than 5. I also assume that a confidence factor can be calculated and adjusted. What would be nice to have is a weight factor where one can say 'value 1 is more important than value 3'. This would require a multidimensional array for input instead of one dimension. I just mashed on the keyboard for these values, but in practice they may be short or long alpha numeric values.

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• Sphinx - delimiters

  - by yoda

  Hi, I would like to know if the Sphinx engine works with any delimiters (like commas and periods in normal MySQL). My question comes from the urge, not to use them at all, but to escape them or at least thay they don't enter in conflict when performing MATCH operations with FULLTEXT searches, since I have problems dealing with them in MySQL by default and I would prefer not to be forced to replace those delimiters by any other characters to provide a good set of results. Sorry if I'm saying something stupid, but I don't have experience with Sphinx or other complementary (?) search engines. To give you an example, if I perform a search with "Passat 2.0 TDI" MySQL by default would identify the period in this case as a delimiter and since the "2" and "0" are too short to be considered words by default, the results would be a bit messed up. Is it easy to handle with Sphinx (or other search engine)? I'm open to suggestions. This is for a large project, with probably more than 500.000 possible records (not trivial at all). Cheers!

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• Unit testing a method with many possible outcomes

  - by Cthulhu

  I've built a simple~ish method that constructs an URL out of approximately 5 parts: base address, port, path, 'action', and a set of parameters. Out of these, only the address part is mandatory, the other parts are all optional. A valid URL has to come out of the method for each permutation of input parameters, such as: address address port address port path address path address action address path action address port action address port path action address action params address path action params address port action params address port path action params andsoforth. The basic approach for this is to write one unit test for each of these possible outcomes, each unit test passing the address and any of the optional parameters to the method, and testing the outcome against the expected output. However, I wonder, is there a Better (tm) way to handle a case like this? Are there any (good) unit test patterns for this? (rant) I only now realize that I've learned to write unit tests a few years ago, but never really (feel like) I've advanced in the area, and that every unit test is a repeat of building parameters, expected outcome, filling mock objects, calling a method and testing the outcome against the expected outcome. I'm pretty sure this is the way to go in unit testing, but it gets kinda tedious, yanno. Advice on that matter is always welcome. (/rant) (note) christmas weekend approaching, probably won't reply to suggestions until next week. (/note)

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• HTML5 on iPhone Safari - data stored by localStorage does not always persist. Why?

  - by Aerodyne

  Hi, I write a simple iPhone web app using HTML5's localStorage. Tests on a 2G device show that data stored using localStorage does not persist after the Safari process is killed although the opened Safari windows are remembered. The data is also lost in a case where I am on a different site on a different Safari window, then I change the window to where the web app in subject is shown. When Safari loads the page it automatically refreshes the page. Then the data is lost. This is a simple test code: <html> <head> <meta name="viewport" content="height=device-height, width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no" /> </head> <body> <script> alert("1:" + localStorage.getItem("test")); localStorage.setItem("test", "123"); alert("2:" + localStorage.getItem("test")); </script> </body> As far as I understand the data should persist! Can anyone shed some light on this behavior? What should I do to get the persistence to work? Thanks! Tom.

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• Java convert time format to integer or long

  - by behrk2

  Hello, I'm wondering what the best method is to convert a time string in the format of 00:00:00 to an integer or a long? My ultimate goal is to be able to convert a bunch of string times to integers/longs, add them to an array, and find the most recent time in the array... I'd appreciate any help, thanks! Ok, based on the answers, I have decided to go ahead and compare the strings directly. However, I am having some trouble. It is possible to have more than one "most recent" time, that is, if two times are equal. If that is the case, I want to add the index of both of those times to an ArrayList. Here is my current code: days[0] = "15:00:00"; days[1] = "17:00:00"; days[2] = "18:00:00"; days[3] = "19:00:00"; days[4] = "19:00:00"; days[5] = "15:00:00"; days[6] = "13:00:00"; ArrayList<Integer> indexes = new ArrayList<Integer>(); String curMax = days[0]; for (int x = 1; x < days.length1; x++) { if (days[x].compareTo(curMax) > 0) { curMax = days[x]; indexes.add(x); System.out.println("INDEX OF THE LARGEST VALUE: " + x); } } However, this is adding index 1, 2, and 3 to the ArrayList... Can anyone help me?

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• trouble with custom 'Text Bubble' component (examples included)

  - by gmoniey

  I'm trying to use a custom Text component to show a series of comments. I got the original idea from: http://www.eonflex.com/?p=40 I've got the base case working but I am stuck with 2 problems I cant seem to figure out: Since I am drawing around the text, the actual height of each bubble is greater than that of the Text field, as a result, the last bubble is always chopped off. I have tried explicitly overriding the height getter, and adding some padding, but I cant seem to get it right. You can see an example here: http://test.lambandtunafish.com/bubbles/CommentTest.swf In my layout, I have 2 VBoxes (one nested inside the other). The first vbox shows a form where the user can enter a comment, and the second box has all the comments. In order to ensure that the scrollbars only show up on the second box, I set minHeight="0" on the nested VBox, but then for some reason, some comments' text is shifted to the right. You can see an example here (look at the first comment): http://test.lambandtunafish.com/bubbles/CommentTest-minHeight.swf Rather than posting the code here, I've provided some links: Container: http://test.lambandtunafish.com/bubbles/CommentTest.mxml Bubble: http://test.lambandtunafish.com/bubbles/CommentBubble.as If anyone has any ideas, I would appreciate it. Thanks!

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• Java Class<T> static method forName() IncompatibleClassChangeError

  - by matt

  Hi, i have this code: private static Importable getRightInstance(String s) throws Exception { Class<? extends Importable> c = Class.forName(s).asSubclass(Importable.class); Importable i = c.newInstance(); return i; } which i can also write private static Importable getRightInstance(String s) throws Exception { Class<? extends Importable> c = (Class<? extends Importable>)Class.forName(s); Importable i = c.newInstance(); return i; } or private static Importable getRightInstance(String s) throws Exception { Class<?> c = Class.forName(s); Importable i = (Importable)c.newInstance(); return i; } where Importable is an interface and s is a string representing an implementing class. Well, in any case it gives the following: Exception in thread "main" java.lang.IncompatibleClassChangeError: class C1 has interface Importable as super class Here is the last snippet of the stack trace: at java.lang.Class.forName(Class.java:169) at Importer.getRightImportable(Importer.java:33) at Importer.importAll(Importer.java:44) at Test.main(Test.java:16) Now, class C1 actually implemens Importable and i totally don't understand why it complaints. Thanks in advance.

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• Multiple leaf methods problem in composite pattern

  - by Ondrej Slinták

  At work, we are developing an PHP application that would be later re-programmed into Java. With some basic knowledge of Java, we are trying to design everything to be easily re-written, without any headaches. Interesting problem came out when we tried to implement composite pattern with huge number of methods in leafs. What are we trying to achieve (not using interfaces, it's just an example): class Composite { ... } class LeafOne { public function Foo( ); public function Moo( ); } class LeafTwo { public function Bar( ); public function Baz( ); } $c = new Composite( Array( new LeafOne( ), new LeafTwo( ) ) ); // will call method Foo in all classes in composite that contain this method $c->Foo( ); It seems like pretty much classic Composite pattern, but problem is that we will have quite many leaf classes and each of them might have ~5 methods (of which few might be different than others). One of our solutions, which seems to be the best one so far and might actually work, is using __call magic method to call methods in leafs. Unfortunately, we don't know if there is an equivalent of it in Java. So the actual question is: Is there a better solution for this, using code that would be eventually easily re-coded into Java? Or do you recommend any other solution? Perhaps there's some different, better pattern I could use here. In case there's something unclear, just ask and I'll edit this post.

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• Commited memory goes to physical RAM or reserves space in the paging file?

  - by Sil

  When I do VirtualAlloc with MEM_COMMIT this "Allocates physical storage in memory or in the paging file on disk for the specified reserved memory pages" (quote from MSDN article http://msdn.microsoft.com/en-us/library/aa366887%28VS.85%29.aspx). All is fine up until now BUT: the description of Commited Bytes Counter says that "Committed memory is the physical memory which has space reserved on the disk paging file(s)." I also read "Windows via C/C++ 5th edition" and this book says that commiting memory means reserving space in the page file.... The last two cases don't make sense to me... If you commit memory, doesn't that mean that you commit to physical storage (RAM)? The page file being there for swaping out currently unused pages of memory in case memory gets low. The book says that when you commit memory you actually reserve space in the paging file. If this were true than that would mean that for a committed page there is space reserved in the paging file and a page frame in physical in memory... So twice as much space is needed ?! Isn't the page file's purpose to make the total physical memory larger than it actually is? If I have a 1G of RAM with a 1G page file = 2G of usable "physical memory"(the book also states this but right after that it says what I discribed at point 2). What am I missing? Thanks.

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• Android: How to do this framing paint?

  - by iDroid Explorer

  I Have Some static images like below: Now, I want is, when i touch on the face or hand, then the selected color should be fill on that skin portion. See below image of result: So how to get the result like above ?? Redo and Undo Functionality Should be also there. I have try with the FloodFill color but doing that i can only able to do color in to the perticular portion. as FloodFill only fill the color till the same pixwl color comes. If the touch place pixel color get change the it will not fill color on it. So Usinf FloodFill i got the result like below image, If i press on the hand, then only hand portion will fill with color, instead of it i want to fill color to the other hand and face also. So Please help me in this case. EDITED After some reply i got the solution like this one. But still there is a memory issue. It consume lots of memory to draw the color. So please can anyone help me for it ?

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• Reflection and Operator Overloads in C#

  - by TenshiNoK

  Here's the deal. I've got a program that will load a given assembly, parse through all Types and their Members and compile a TreeView (very similar to old MSDN site) and then build HTML pages for each node in the TreeView. It basically takes a given assembly and allows the user to create their own MSDN-like library for it for documentation purposes. Here's the problem I've run into: whenever an operator overload is encounted in a defined class, reflection returns that as a "MethodInfo" with the name set to something like "op_Assign" or "op_Equality". I want to be able to capture these and list them properly, but I can't find anything in the MethodInfo object that is returned to accurately identify that I'm looking at an operator. I definitely don't want to just capture everything that starts with "op_", since that will most certainly (at some point) will pick up a method it's not supposed to. I know that other methods and properties that are "special cases" like this one have the "IsSpecialName" property set, but appearantly that's not the case with operators. I've been scouring the 'net and wracking my brain to two days trying to figure this one out, so any help will be greatly appreciated.

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• How to build a dynamic resize-able Flash player

  - by Leon

  Morning stackers! So my question today isn't dealing with any code, but how to go about this the correct way from the start. I have a video player built to a static size (max: 800x600) which I'll have to re-code every time I need it to be a different size. What I need it to do in the near future is dynamically resize itself and all the elements inside of it based on 1 width variable that it will received either from HTML or XML. Now to me there are 2 ways to go about this: Start with the smallest size possible and resize upwards, but I'm unsure of how the Flash movie will actually expand upwards as of right now. Or 2, start with the largest size possible (in this case 800x600) and size everything down. Step 1, I think seems to be the better way to go about this (ala YouTube style), but Step 2 also seems like it could be the easier way? A friend of mine mentioned that I should go with the larger size and have elements resize in each class, then fix to the upper left hand corner. However for the player to fit inside of certain div columns on sites, blogs whatever he said that there will have to be an HTML/CSS side of this... meaning that the div containing the resized flash player will have to cover up the areas of the Flash movie that are not to be shown? Is that possible to put a 800x600 flash movie into a div that smaller then 800 pixels wide? And cover it up with another div? Anyways, my mission is to be able to have a dynamically sized player like this: Thoughts? Recommendations? Best practices for this before I start?

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• Why does the Maven goal "package" include the resources in the jar, but the goal "jar:jar" doesnt?

  - by Bernhard V

  Hi, when I package my project with the Maven goal "package", the resources are included as well. They are originally located in the directory "src/main/resources". Because I want to create an executable jar and add the classpath to the manifest, I'm using maven-jar-plugin. I've configured it as the following likes: <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-jar-plugin</artifactId> <version>2.2</version> <configuration> <archive> <manifest> <addClasspath>true</addClasspath> <mainClass>at.sozvers.stp.zpv.ekvkumsetzer.Main</mainClass> </manifest> </archive> </configuration> </plugin> Why won't the jar file created with "jar:jar" include my resources as well. As far as I'm concerned it should use the same directories as the "package" goal (which are in my case inherited from the Maven Super POM).

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• Want to add a functional language to my toolchest. Haskell or Erlang?

  - by sean.johnson

  I've been an OO/procedural guy my whole career except in school where I did a lot of logic programming (Prolog). I work on an amazing variety of projects (freelancer) and so I don't want the tools I know and understand to hold me back from using the right tool for the job. I've decided I should know a functional programming language. I've narrowed the field to Haskell and Erlang. What are the pros and cons, advantages and disadvantages, and major trade offs of Haskell and Erlang? How do I decide in a rational way, which is the better path? This is a big time investment, so I'd like to chose wisely. Is there a good case to be made for something else entirely? F#, Scala Ocaml? (BTW, I'm normally a Ruby/C/Obj.C guy, so I'm not terribly impressed or dependent on the JVM as a runtime. It's completely neutral to me. It's a fine runtime, I don't hold it for or against a language. I don't use Microsoft products though, so a .NET runtime would be a negative.)

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• DefaultStyledDocument.styleChanged(Style style) may not run in a timely manner?

  - by Paul Reiners

  I'm experiencing an intermittent problem with a class that extends javax.swing.text.DefaultStyledDocument. This document is being sent to a printer. Most of the time the formatting of the document looks correct, but once in a while it doesn't. It looks like some of the changes in the formatting have not been applied. I took a look at the DefaultStyledDocument.styleChanged(Style style) code: /** * Called when any of this document's styles have changed. * Subclasses may wish to be intelligent about what gets damaged. * * @param style The Style that has changed. */ protected void styleChanged(Style style) { // Only propagate change updated if have content if (getLength() != 0) { // lazily create a ChangeUpdateRunnable if (updateRunnable == null) { updateRunnable = new ChangeUpdateRunnable(); } // We may get a whole batch of these at once, so only // queue the runnable if it is not already pending synchronized(updateRunnable) { if (!updateRunnable.isPending) { SwingUtilities.invokeLater(updateRunnable); updateRunnable.isPending = true; } } } } /** * When run this creates a change event for the complete document * and fires it. */ class ChangeUpdateRunnable implements Runnable { boolean isPending = false; public void run() { synchronized(this) { isPending = false; } try { writeLock(); DefaultDocumentEvent dde = new DefaultDocumentEvent(0, getLength(), DocumentEvent.EventType.CHANGE); dde.end(); fireChangedUpdate(dde); } finally { writeUnlock(); } } } Does the fact that SwingUtilities.invokeLater(updateRunnable) is called, rather than invokeAndWait(updateRunnable), mean that I can't count on my formatting changes appearing in the document before it is rendered? If that is the case, is there a way to ensure that I don't proceed with rendering until the updates have occurred?

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• Managing My Database in Source Control

  - by Jason

  As I am working with a new database project (within VS2008), and as I have never developed a database from scratch, I immediately began looking into how to manage a database within source control (in this case, Subversion). I found some information on SO, including this post: Keeping development databases in multiple environments in sync. One of the answers in particular pointed to a number of a links, all of which had good, useful information. I was reading a series of posts by K. Scott Allen which describe how he manages database change. From my reading (and please pardon the noobishness of my question), it seems as though the database itself is never checked into a repository. Rather, scripts that can build the database, along with test data (which is also populated from scripts) is checked into the repository. Ultimately, this means that, when a developer is testing his or her app, these scripts, which are part of the build process, are run. This ensures that the database is up-to-date, but is also run locally from every developer's machine. This makes sense to me (if I am indeed reading that correctly). However, if I am missing something, I would appreciate correction or additional guidance. In addition, another question I wanted to ask - does this also mean that I should NOT check in the mdf or ldf files that are created from Visual Studio? Thanks for any help and additional insight. Always appreciated.

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• Speed comparison - Template specialization vs. Virtual Function vs. If-Statement

  - by Person

  Just to get it out of the way... Premature optimization is the root of all evil Make use of OOP etc. I understand. Just looking for some advice regarding the speed of certain operations that I can store in my grey matter for future reference. Say you have an Animation class. An animation can be looped (plays over and over) or not looped (plays once), it may have unique frame times or not, etc. Let's say there are 3 of these "either or" attributes. Note that any method of the Animation class will at most check for one of these (i.e. this isn't a case of a giant branch of if-elseif). Here are some options. 1) Give it boolean members for the attributes given above, and use an if statement to check against them when playing the animation to perform the appropriate action. Problem: Conditional checked every single time the animation is played. 2) Make a base animation class, and derive other animations classes such as LoopedAnimation and AnimationUniqueFrames, etc. Problem: Vtable check upon every call to play the animation given that you have something like a vector<Animation>. Also, making a separate class for all of the possible combinations seems code bloaty. 3) Use template specialization, and specialize those functions that depend on those attributes. Like template<bool looped, bool uniqueFrameTimes> class Animation. Problem: The problem with this is that you couldn't just have a vector<Animation> for something's animations. Could also be bloaty. I'm wondering what kind of speed each of these options offer? I'm particularly interested in the 1st and 2nd option because the 3rd doesn't allow one to iterate through a general container of Animations. In short, what is faster - a vtable fetch or a conditional?

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• Split node list to parts.

  - by Kalinin

  xml: <mode>1</mode> <mode>2</mode> <mode>3</mode> <mode>4</mode> <mode>5</mode> <mode>6</mode> <mode>7</mode> <mode>8</mode> <mode>9</mode> <mode>10</mode> <mode>11</mode> <mode>12</mode> i need to separate it on parts (for ex. on 4): xslt: <xsl:variable name="vNodes" select="mode"/> <xsl:variable name="vNumParts" select="4"/> <xsl:variable name="vNumCols" select="ceiling(count($vNodes) div $vNumParts)"/> <xsl:for-each select="$vNodes[position() mod $vNumCols = 1]"> <xsl:variable name="vCurPos" select="(position()-1)*$vNumCols +1"/> <ul> <xsl:for-each select="$vNodes[position() >= $vCurPos and not(position() > $vCurPos + $vNumCols -1)]"> <li><xsl:value-of select="."/></li> </xsl:for-each> </ul> </xsl:for-each> this code is written by Dimitre Novatchev - great coder)) but for the number of nodes less then number of parts (for ex. i have 2 modes) this code does not work - it outputs nothing. How it upgrade for that case (without choose construction)?

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• How to Implement Rich Document Editor for iPhone

  - by benjismith

  I'm just getting started on a new iPhone/iPad development project, and I need to display a document with rich styled text (potentially with embedded images). The user will touch the document, dragging to highlight individual words or multiline text spans. When the text is highlighted, a context menu will appear, letting them change the color of highlighting or add margin notes (or other various bits of structured metadata). If you're familiar with adding comments to a Word document (or annotating a PDF), then this is the same sort of thing. But in my case, the typical user will spend many many hours within the app, adding thousands (in some cases, tens of thousands) of small annotations to the central document. All of those bits of metadata will be stored locally awaiting synchronization with a remote web service. I've read other pieces of advice, where developers suggest creating a UIWebView control and passing it an HTML string. But that seems kind of clunky, especially with all the context-sensitivity that I want to include. Anyhow, I'm brand new to iPhone development and Objective-C, though I have ten years of software development experience, using a variety of languages on many different platforms, so I'm not worried about getting my hands dirty writing new functionality from scratch. But if anyone has experience building a similar kind of component, I'm interested in hearing strategies for enabling that kind of rich document markup and annotation.

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• C++ variable to const expression

  - by user1344784

  template <typename Real> class A{ }; template <typename Real> class B{ }; //... a few dozen more similar template classes class Computer{ public slots: void setFrom(int from){ from_ = from; } void setTo(int to){ to_ = to; } private: template <int F, int T> void compute(){ using boost::fusion::vector; using boost::fusion::at_c; vector<A<float>, B<float>, ...> v; at_c<from_>(v).operator()(at_c<to_>(v)); //error; needs to be const-expression. }; This question isn't about Qt, but there is a line of Qt code in my example. The setFrom() and setTo() are functions that are called based on user selection via the GUI widget. The root of my problem is that 'from' and 'to' are variables. In my compute member function I need to pick a type (A, B, etc.) based on the values of 'from' and 'to'. The only way I know how to do what I need to do is to use switch statements, but that's extremely tedious in my case and I would like to avoid. Is there anyway to convert the error line to a constant-expression?

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• Which options do I have for Java process communication?

  - by Dmitriy Matveev

  We have a place in a code of such form: void processParam(Object param) { wrapperForComplexNativeObject result = jniCallWhichMayCrash(param); processResult(result); } processParam - method which is called with many different arguments. jniCallWhichMayCrash - a native method which is intended to do some complex processing of it's parameter and to create some complex object. It can crash in some cases. wrapperForComplexNativeObject - wrapper type generated by SWIG processResult - a method written in pure Java which processes it's parameter by creation of several kinds (by the kinds I'm not meaning classes, maybe some like hierarchies) of objects: 1 - Some non-unique objects which are referencing each other (from the same hierarchy), these objects can have duplicates created from the invocations of processParam() method with different parameter values. Since it's costly to keep all the duplicates it's necessary to cache them. 2 - Some unique objects which are referencing each other (from the same hierarchy) and some of the objects of 1st kind. After processParam is executed for each of the arguments from some set the data created in processResult will be processed together. The problem is in fact that jniCallWhichMayCrash method may crash the entire JVM and this will be very bad. The reason of crash may be such that it can happen for one argument value and not for the other. We've decided that it's better to ignore crashes inside of JVM and just skip some chunks of data when such crashes occur. In order to do this we should run processParam function inside of separate process and pass the result somehow (HOW? HOW?! This is a question) to the main process and in case of any crashes we will only lose some part of data (It's ok) without lose of everything else. So for now the main problem is implementation of transport between different processes. Which options do I have? I can think about serialization and transmitting of binary data by the streams, but serialization may be not very fast due to object complexity. Maybe I have some other options of implementing this?

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• Design by contracts and constructors

  - by devoured elysium

  I am implementing my own ArrayList for school purposes, but to spice up things a bit I'm trying to use C# 4.0 Code Contracts. All was fine until I needed to add Contracts to the constructors. Should I add Contract.Ensures() in the empty parameter constructor? public ArrayList(int capacity) { Contract.Requires(capacity > 0); Contract.Ensures(Size == capacity); _array = new T[capacity]; } public ArrayList() : this(32) { Contract.Ensures(Size == 32); } I'd say yes, each method should have a well defined contract. On the other hand, why put it if it's just delegating work to the "main" constructor? Logicwise, I wouldn't need to. The only point I see where it'd be useful to explicitly define the contract in both constructors is if in the future we have Intelisense support for contracts. Would that happen, it'd be useful to be explicit about which contracts each method has, as that'd appear in Intelisense. Also, are there any books around that go a bit deeper on the principles and usage of Design by Contracts? One thing is having knowledge of the syntax of how to use Contracts in a language (C#, in this case), other is knowing how and when to use it. I read several tutorials and Jon Skeet's C# in Depth article about it, but I'd like to go a bit deeper if possible. Thanks

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