technical links - Page 442

Optimising speeds in HDF5 using Pytables

- by Sree Aurovindh

The problem is with respect to the writing speed of the computer (10 * 32 bit machine) and the postgresql query performance.I will explain the scenario in detail. I have data about 80 Gb (along with approprite database indexes in place). I am trying to read it from Postgresql database and writing it into HDF5 using Pytables.I have 1 table and 5 variable arrays in one hdf5 file.The implementation of Hdf5 is not multithreaded or enabled for symmetric multi processing.I have rented about 10 computers for a day and trying to write them inorder to speed up my data handling. As for as the postgresql table is concerned the overall record size is 140 million and I have 5 primary- foreign key referring tables.I am not using joins as it is not scalable So for a single lookup i do 6 lookup without joins and write them into hdf5 format. For each lookup i do 6 inserts into each of the table and its corresponding arrays. The queries are really simple select * from x.train where tr_id=1 (primary key & indexed) select q_t from x.qt where q_id=2 (non-primary key but indexed) (similarly five queries) Each computer writes two hdf5 files and hence the total count comes around 20 files. Some Calculations and statistics: Total number of records : 14,37,00,000 Total number of records per file : 143700000/20 =71,85,000 The total number of records in each file : 71,85,000 * 5 = 3,59,25,000 Current Postgresql database config : My current Machine : 8GB RAM with i7 2nd generation Processor. I made changes to the following to postgresql configuration file : shared_buffers : 2 GB effective_cache_size : 4 GB Note on current performance: I have run it for about ten hours and the performance is as follows: The total number of records written for each file is about 6,21,000 * 5 = 31,05,000 The bottle neck is that i can only rent it for 10 hours per day (overnight) and if it processes in this speed it will take about 11 days which is too high for my experiments. Please suggest me on how to improve. Questions: 1. Should i use Symmetric multi processing on those desktops(it has 2 cores with about 2 GB of RAM).In that case what is suggested or prefereable? 2. If i change my postgresql configuration file and increase the RAM will it enhance my process. 3. Should i use multi threading.. In that case any links or pointers would be of great help Thanks Sree aurovindh V

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How to keep a local value from being set when a binding fails (so inherited values will propagate)

- by redoced

Consider the following scenario: I want to bind the TextElement.FontWeight property to an xml attribute. The xml looks somewhat like this and has arbitrary depth. <text font-weight="bold"> bold text here <inlinetext>more bold text</inlinetext> even more bold text </text> I use hierarchical templating to display the text, no problem there, but having a Setter in the template style like: <Setter Property="TextElement.FontWeight" Value="{Binding XPath=@font-weight}"/> sets the fontweight correctly on the first level, but overwrites the second level with null (as the binding can't find the xpath) which reverts to Fontweight normal. I tried all sorts of things here but nothing quite seems to work. e.g. i used a converter to return UnsetValue, which didn't work. I'm currently trying with: <Setter Property="custom:AttributeInserter.Wrapper" Value="{custom:AttributeInserter Property=TextElement.FontWeight, Binding={Binding XPath=@font-weight}}"/> Codebehind: public static class AttributeInserter { public static AttributeInserterExtension GetWrapper(DependencyObject obj) { return (AttributeInserterExtension)obj.GetValue(WrapperProperty); } public static void SetWrapper(DependencyObject obj, AttributeInserterExtension value) { obj.SetValue(WrapperProperty, value); } // Using a DependencyProperty as the backing store for Wrapper. This enables animation, styling, binding, etc... public static readonly DependencyProperty WrapperProperty = DependencyProperty.RegisterAttached("Wrapper", typeof(AttributeInserterExtension), typeof(AttributeInserter), new UIPropertyMetadata(pcc)); static void pcc(DependencyObject o,DependencyPropertyChangedEventArgs e) { var n=e.NewValue as AttributeInserterExtension; var c = o as FrameworkElement; if (n == null || c==null || n.Property==null || n.Binding==null) return; var bex = c.SetBinding(n.Property, n.Binding); bex.UpdateTarget(); if (bex.Status == BindingStatus.UpdateTargetError) c.ClearValue(n.Property); } } public class AttributeInserterExtension : MarkupExtension { public override object ProvideValue(IServiceProvider serviceProvider) { return this; } public DependencyProperty Property { get; set; } public Binding Binding { get; set; } } which kinda works, but can't track changes of the property Any ideas? Any links? thx for the help

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What are the Options for Storing Hierarchical Data in a Relational Database?

- by orangepips

Good Overviews One more Nested Intervals vs. Adjacency List comparison: the best comparison of Adjacency List, Materialized Path, Nested Set and Nested Interval I've found. Models for hierarchical data: slides with good explanations of tradeoffs and example usage Representing hierarchies in MySQL: very good overview of Nested Set in particular Hierarchical data in RDBMSs: most comprehensive and well organized set of links I've seen, but not much in the way on explanation Options Ones I am aware of and general features: Adjacency List: Columns: ID, ParentID Easy to implement. Cheap node moves, inserts, and deletes. Expensive to find level (can store as a computed column), ancestry & descendants (Bridge Hierarchy combined with level column can solve), path (Lineage Column can solve). Use Common Table Expressions in those databases that support them to traverse. Nested Set (a.k.a Modified Preorder Tree Traversal) First described by Joe Celko - covered in depth in his book Trees and Hierarchies in SQL for Smarties Columns: Left, Right Cheap level, ancestry, descendants Compared to Adjacency List, moves, inserts, deletes more expensive. Requires a specific sort order (e.g. created). So sorting all descendants in a different order requires additional work. Nested Intervals Combination of Nested Sets and Materialized Path where left/right columns are floating point decimals instead of integers and encode the path information. Bridge Table (a.k.a. Closure Table: some good ideas about how to use triggers for maintaining this approach) Columns: ancestor, descendant Stands apart from table it describes. Can include some nodes in more than one hierarchy. Cheap ancestry and descendants (albeit not in what order) For complete knowledge of a hierarchy needs to be combined with another option. Flat Table A modification of the Adjacency List that adds a Level and Rank (e.g. ordering) column to each record. Expensive move and delete Cheap ancestry and descendants Good Use: threaded discussion - forums / blog comments Lineage Column (a.k.a. Materialized Path, Path Enumeration) Column: lineage (e.g. /parent/child/grandchild/etc...) Limit to how deep the hierarchy can be. Descendants cheap (e.g. LEFT(lineage, #) = '/enumerated/path') Ancestry tricky (database specific queries) Database Specific Notes MySQL Use session variables for Adjacency List Oracle Use CONNECT BY to traverse Adjacency Lists PostgreSQL ltree datatype for Materialized Path SQL Server General summary 2008 offers HierarchyId data type appears to help with Lineage Column approach and expand the depth that can be represented.

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How to get started with testing(jMock)

- by London

Hello, I'm trying to learn how to write tests. I'm also learning Java, I was told I should learn/use/practice jMock, I've found some articles online that help to certain extend like : http://www.theserverside.com/news/1365050/Using-JMock-in-Test-Driven-Development http://jeantessier.com/SoftwareEngineering/Mocking.html#jMock And most articles I found was about test driven development, write tests first then write code to make the test pass. I'm not looking for that at the moment, I'm trying to write tests for already existing code with jMock. The official documentation is vague to say the least and just too hard for me. Does anybody have better way to learn this. Good books/links/tutorials would help me a lot. thank you EDIT - more concrete question : http://jeantessier.com/SoftwareEngineering/Mocking.html#jMock - from this article Tried this to mock this simple class : import java.util.Map; public class Cache { private Map<Integer, String> underlyingStorage; public Cache(Map<Integer, String> underlyingStorage) { this.underlyingStorage = underlyingStorage; } public String get(int key) { return underlyingStorage.get(key); } public void add(int key, String value) { underlyingStorage.put(key, value); } public void remove(int key) { underlyingStorage.remove(key); } public int size() { return underlyingStorage.size(); } public void clear() { underlyingStorage.clear(); } } Here is how I tried to create a test/mock : public class CacheTest extends TestCase { private Mockery context; private Map mockMap; private Cache cache; @Override @Before public void setUp() { context = new Mockery() { { setImposteriser(ClassImposteriser.INSTANCE); } }; mockMap = context.mock(Map.class); cache = new Cache(mockMap); } public void testCache() { context.checking(new Expectations() {{ atLeast(1).of(mockMap).size(); will(returnValue(int.class)); }}); } } It passes the test and basically does nothing, what I wanted is to create a map and check its size, and you know work some variations try to get a grip on this. Understand better trough examples, what else could I test here or any other exercises would help me a lot. tnx

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Stop output of image if no record - paperclip - Ruby on rails

- by bgadoci

I have just installed paperclip into my ruby on rails blog application. Everything is working great...too great. I am trying to figure out how to tell paperclip not to output anything if there is no record in the table so that I don't have broken image links everywhere. How, and where, do I do this? Here is my code: class Post < ActiveRecord::Base has_attached_file :photo, :styles => { :small => "150x150"} validates_presence_of :body, :title has_many :comments, :dependent => :destroy has_many :tags, :dependent => :destroy has_many :ugtags, :dependent => :destroy has_many :votes, :dependent => :destroy belongs_to :user after_create :self_vote def self_vote # I am assuming you have a user_id field in `posts` and `votes` table. self.votes.create(:user => self.user) end cattr_reader :per_page @@per_page = 10 end View <% div_for post do %> <div id="post-wrapper"> <div id="post-photo"> <%= image_tag post.photo.url(:small) %> </div> <h2><%= link_to_unless_current h(post.title), post %></h2> <div class="light-color"> <i>Posted <%= time_ago_in_words(post.created_at) %></i> ago </div> <%= simple_format truncate(post.body, :length => 600) %> <div id="post-options"> <%= link_to "Read More >>", post %> | <%= link_to "Comments (#{post.comments.count})", post %> | <%= link_to "Strings (#{post.tags.count})", post %> | <%= link_to "Contributions (#{post.ugtags.count})", post %> | <%= link_to "Likes (#{post.votes.count})", post %> </div> </div> <% end %>

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IPHONE DEVELOPMENT PROFILE EXPIRED - I TRIED EVERYTHING AND YES, I READ THE DOCS

- by theiphoneguy

I really combed this site and others. I read and re-read the related links here and the Apple docs. I'm sorry, but either I am obviously missing something right under my nose, or this Apple profile/certificate stuff is a bit convoluted. Here it is: I have a product in the App Store. I have updated it several times and users like it. My development profile recently expired just when I was improving the app for its next release. I can run the app in the simulator. I can compile and put the distribution build on my iPhone just fine. I went to the Apple portal and renewed the development profile. I downloaded it and installed it in Xcode. I see it in the Organize window. I see it on my iPhone. I CANNOT put the debug build on my iPhone to debug or run with Instruments. The message is that either there is not a valid signed profile or it is untrusted. I subsequently tried to download and install the certificate to my Mac's keychain. Still no success. I checked the code signing section of Project settings and also for the target and the root. All appears to indicate that it is using the expected development profile for debug. Yes, I had deleted the old profile from my iPhone, from the Organizer. I cleaned the Xcode cache and all targets. I have done all of this several times and in varying sequences to try to cover every possibility. I am ready to do anything to be able to debug with Instruments in order to check for leaks or high memory usage. Even though the distribution compile runs fine on my iPhone and plays well with other running processes, I will not release anything without a leaks/memory test. Any ideas will be appreciated. If I missed something obvious, please forgive me - it was not due to just posting a question without searching for similar postings. Thanks!

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xsl:variable contains nodeset. How to output nth node of variable?

- by dnagirl

I am transforming an XML document. There is an attribute @prettydate that is a string similar to "Friday, May 7, 2010". I want to split that string and add links to the month and the year. I am using the exslt:strings module and I can add any other necessary EXSLT module. This is my code so far: <xsl:template match="//calendar"> <xsl:variable name="prettyparts"> <xsl:value-of select="str:split(@prettydate,', ')"/> </xsl:variable> <table class='day'> <thead> <caption><xsl:value-of select="$prettyparts[1]"/>, <a> <xsl:attribute name='href'><xsl:value-of select="$baseref"/>?date=<xsl:value-of select="@highlight"/>&per=m</xsl:attribute> <xsl:value-of select='$prettyparts[2]'/> </a> <xsl:value-of select='$prettyparts[3]'/>, <a> <xsl:attribute name='href'><xsl:value-of select="$baseref"/>?date=<xsl:value-of select="@highlight"/>&per=y</xsl:attribute> <xsl:value-of select='$prettyparts[4]'/> </a> </caption>  I have verified, by running $prettyparts through a <xml:for-each/> that I am getting the expected nodeset: <token>Friday</token> <token>May</token> <token>7</token> <token>2010</token> But no matter which way I attempt to refer to a particular <token> directly (not in a foreach) I get nothing or various errors to do with invalid types. Here's some of the syntax I've tried: <xsl:value-of select="$prettyparts[2]"/> <xsl:value-of select="$prettyparts/token[2]"/> <xsl:value-of select="exsl:node-set($prettyparts/token[2])"/> <xsl:value-of select="exsl:node-set($prettyparts/token)[2]"/> Any idea what the expression ought to be?

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Android: Autostart app and load preferences

- by BBoom

Hi, I have a problem with initializing my app properly after the autostart. I've managed to get an autostart to work, after a reboot the app is shown as started but the timer's are not. My guess is that the "onCreate" function of MyApp is not called when I call the context.startService(). The timers are set in the doActivity() function of MyApp. I would greatly appreciate any tips on what I could be doing wrong or links to good tutorials. :) The manifest: <activity android:name=".MyApp" android:label="@string/app_name"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> <receiver android:name="MyApp_Receiver"> <intent-filter> <action android:name="android.intent.action.BOOT_COMPLETED" /> <category android:name="android.intent.category.DEFAULT" /> </intent-filter> </receiver>[/syntax] MyApp_Receiver is a BoradcastReciever with the following two functions public void onReceive(Context context, Intent intent) { // Do Autostart if intent is "BOOT_COMPLETED" if ((intent.getAction() != null) && (intent.getAction().equals("android.intent.action.BOOT_COMPLETED"))) { // Start the service context.startService(new Intent(context, MyApp.class)); } // Else do activity else MAIN_ACTIVITY.doActivity(); } public static void setMainActivity(MyApp activity) { MAIN_ACTIVITY = activity; } MyApp extends PreferenceActivity and has an onCreate() and a doActivity(), the doActivity() reads out the preferences and sets a timer depending on them. public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); // Show preferences addPreferencesFromResource(R.xml.preferences);; // Register Preference Click Listeners getPreferenceScreen().getSharedPreferences().registerOnSharedPreferenceChangeListener(this); // Prepare for one-shot alarms if (mIntent == null) { mIntent = new Intent(MyApp.this, MyApp_Receiver.class); mSender = PendingIntent.getBroadcast(MyApp.this, 0, mIntent, 0); MyApp_Receiver.setMainActivity(this); } // Refresh and set all timers on start doActivity(); }

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Please recommend me intermediate-to-advanced Python books to buy.

- by anonnoir

I'm in the final year, final semester of my law degree, and will be graduating very soon. (April, to be specific.) But before I begin practice, I plan to take 2 two months off, purely for serious programming study. So I'm currently looking for some Python-related books, gauged intermediate to advanced, which are interesting (because of the subject matter itself) and possibly useful to my future line of work. I've identified 2 possible purchases at the moment: Natural Language Processing with Python. The law deals mostly with words, and I've quite a number of ideas as to where I might go with NLP. Data extraction, summaries, client management systems linked with document templates, etc. Programming Collective Intelligence. This book fascinates me, because I've always liked the idea of machine learning (and I'm currently studying it by the side too, for fun). I'd like to build/play around with Web 2.0 applications; and who knows if I can apply some of the things I learn to my legal work. (E.g. Playground experiments to determine how and under what circumstances judges might be biased, by forcing algorithms to pore through judgments and calculate similarities, etc.) Please feel free to criticize my current choices, but do at least offer or recommend other books that I should read in their place. My budget can deal with 4 books, max. These books will be used heavily throughout the 2 months; I will be reading them back to back, absorbing the explanations given, and hacking away at their code. Also, the books themselves should satisfy 2 main criteria: Application. The book must teach how to solve problems. I like reading theory, but I want to build things and solve problems first. Even playful applications are fine, because games and experiments always have real-world applications sooner or later. Readability. I like reading technical books, no matter how difficult they are. I enjoy the effort and the feeling that you're learning something. But the book shouldn't contain code or explanations that are too cryptic or erratic. Even if it's difficult, the book's content should be accessible with focused reading. Note: I realize that I am somewhat of a beginner to the whole programming thing, so please don't put me down. But from experience, I think it's better to aim up and leave my comfort zone when learning new things, rather than to just remain stagnant the way I am. (At least the difficulty gives me focus: i.e. if a programmer can be that good, perhaps if I sustain my own efforts I too can be as good as him someday.) If anything, I'm also a very determined person, so two months of day-to-night intensive programming study with nothing else on my mind should, I think, give me a bit of a fighting chance to push my programming skills to a much higher level.

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Ie7 float problems and hiperlinks not clickable

- by Uffo

Markup <ul class="navigation clearfix"> <li class="navigation-top"></li> <div class="first-holder" style="height:153px;"> <dl class="hold-items clearfix"> <dd class="clearfix with"><a href="http://site.com" title="Protokoll">Protokoll</a></dd> <dd class="with-hover"><a href="http://site.com" title="Mein/e Unternehmen">Mein/e Unternehmen</a></dd> <dd class="with"><a class="face-me" href="http://site.com" title="Erweiterte Suche">Erweiterte Suche</a></dd> <dd class="with"><a href="http://site.com" title="Abmelden">Abmelden</a></dd> </dl> </div> <li class="navigation-bottom"></li> </ul> Css: .first-holder{height:304px;position:relative;width:178px;overflow:hidden;margin-bottom:0px;padding-bottom: 0px;} .hold-items{top:0px;position:absolute;} .navigation dd.with{line-height:38px;background:url('/images/sprite.png') no-repeat -334px -46px;width:162px;height:38px;padding-bottom:0px;overflow: hidden;} .navigation dd.with a{position:relative;outline:0;display:block;font-weight:bold;color:#3f78c0;padding-left:10px;line-height:38px;} .with-hover{background:url('/images/sprite.png') no-repeat -505px -47px;width:178px;height:38px;line-height:38px;overflow:none;} .with-hover a{position:relative;display:block;font-weight:bold;color:#fff;padding-left:10px} .navigation-top{background:url('/images/sprite.png') no-repeat -694px -46px;width:160px;height:36px;} .navigation-top a{display:block;outline:0;height:20px;padding-top:18px;padding-left:138px;} .navigation-top a span{display:block;background:url('/images/sprite.png') no-repeat -212px -65px;width:8px;height:6px;} .navigation-bottom{background:url('/images/sprite.png') no-repeat -784px -402px;width:160px;height:37px;} .navigation-bottom a{display:block;outline:0;height:20px;padding-top:18px;padding-left:138px;} .navigation-bottom a span{display:block;background:url('/images/sprite.png') no-repeat -212px -74px;width:8px;height:6px;} Also the links, are not clickable, if I click on a link in IE7 it doesn't do the action..it doesn't redirect me to the location. This is how it looks in IE7: http://screencast.com/t/MGY4NjljZjc This is how it look in IE8,Firefox,Chrome and so on http://screencast.com/t/MzhhMDQ1M What I'm doing wrong PS: .navigation-top a span and .navigation-bottom a span I'm using some where else, but that it's ok it works fine.

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WndProc(ref Message m), Prevent minimize Games, Send key strokes.

- by Stanomatic

Overview: I am going to create a touch application that interfaces with games and other apps. This concept is similar to the app found on touch-buddy.com but I will be using C# and WPF instead of how the application is written in Perl. I have a few challenges I would like to evaluate. The touch-buddy app uses two approaches while interacting with games; 1. Client mode (Same machine runs both game and touch-buddy). 2. Server / Client mode where a separate box sends commands to the game machine. The reason I believe for this method was to circumvent the issue with games minimizing. In Client only mode I am faced with the issue where I touch a screen OTHER than the main screen where the game is viewed and then the game minimizes. Not all games have this behavior but I would like to conquer the games that do minimize and prevent it. Is it possible to keep a game front and center Focused and prevent minimizing utilizing C# WndProc(ref Message m)? I have been experimenting with WndProc(ref Message m) where I created a win form and when I press minimize on my own Win form and it will close an instance of notepad. This proves to me that I can capture a message, prevent that message from bubbling up and then send a message to another application. I then tried to click on notepad with my touch screen and keep my win form application in focus and not minimize. At this point I am unsuccessful. I need more time understanding message codes. Is this the right approach? Can it be done? Should I look at other libraries such as Windows Automation? Key input is my other concern. What is the best way to send key strokes to other apps/games. Should I tap into DirectX, use some kind of send key, Automation Framework? Can any of these handle the multiple key strokes that some simulation games require? I appreciate any links and or insight you may have. If you have gone down this path for any reason I would love to hear your comments. Stan

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How to play audio in Java Application

- by user577829

I'm making a java application and I need to play audio. I'm playing mainly small sound files of my cannon firing (its a cannon shooting game) and the projectiles exploding, though I plan on having looping background music. I have found two different methods to accomplish this, but both don't work how I want. The first method is literally a method: public void playSoundFile(File file) {//http://java.ittoolbox.com/groups/technical-functional/java-l/sound-in-an-application-90681 try { //get an AudioInputStream AudioInputStream ais = AudioSystem.getAudioInputStream(file); //get the AudioFormat for the AudioInputStream AudioFormat audioformat = ais.getFormat(); System.out.println("Format: " + audioformat.toString()); System.out.println("Encoding: " + audioformat.getEncoding()); System.out.println("SampleRate:" + audioformat.getSampleRate()); System.out.println("SampleSizeInBits: " + audioformat.getSampleSizeInBits()); System.out.println("Channels: " + audioformat.getChannels()); System.out.println("FrameSize: " + audioformat.getFrameSize()); System.out.println("FrameRate: " + audioformat.getFrameRate()); System.out.println("BigEndian: " + audioformat.isBigEndian()); //ULAW format to PCM format conversion if ((audioformat.getEncoding() == AudioFormat.Encoding.ULAW) || (audioformat.getEncoding() == AudioFormat.Encoding.ALAW)) { AudioFormat newformat = new AudioFormat(AudioFormat.Encoding.PCM_SIGNED, audioformat.getSampleRate(), audioformat.getSampleSizeInBits() * 2, audioformat.getChannels(), audioformat.getFrameSize() * 2, audioformat.getFrameRate(), true); ais = AudioSystem.getAudioInputStream(newformat, ais); audioformat = newformat; } //checking for a supported output line DataLine.Info datalineinfo = new DataLine.Info(SourceDataLine.class, audioformat); if (!AudioSystem.isLineSupported(datalineinfo)) { //System.out.println("Line matching " + datalineinfo + " is not supported."); } else { //System.out.println("Line matching " + datalineinfo + " is supported."); //opening the sound output line SourceDataLine sourcedataline = (SourceDataLine) AudioSystem.getLine(datalineinfo); sourcedataline.open(audioformat); sourcedataline.start(); //Copy data from the input stream to the output data line int framesizeinbytes = audioformat.getFrameSize(); int bufferlengthinframes = sourcedataline.getBufferSize() / 8; int bufferlengthinbytes = bufferlengthinframes * framesizeinbytes; byte[] sounddata = new byte[bufferlengthinbytes]; int numberofbytesread = 0; while ((numberofbytesread = ais.read(sounddata)) != -1) { int numberofbytesremaining = numberofbytesread; sourcedataline.write(sounddata, 0, numberofbytesread); } } } catch (Exception e) { e.printStackTrace(); } } The problem with this is that my entire program stops until the sound file is finished, or at least nearly finished. The second method is this: File file = new File("Launch1.wav"); AudioClip clip; try { clip = JApplet.newAudioClip(file.toURL()); clip.play(); } catch (Exception e) { e.getMessage(); } The problem I have here is that every time the sound file ends early or doesn't play at all depending on where I place the code. Is their any way to play sound without the above mentioned problems? Am I doing something wrong? Any help is greatly appreciated.

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Design patterns and interview question

- by user160758

When I was learning to code, I read up on the design patterns like a good boy. Long after this, I started to actually understand them. Design discussions such as those on this site constantly try to make the rules more and more general, which is good. But there is a line, over which it becomes over-analysis starts to feed off itself and as such I think begins to obfuscate the original point - for example the "What's Alternative to Singleton" post and the links contained therein. http://stackoverflow.com/questions/1300655/whats-alternative-to-singleton I say this having been asked in both interviews I’ve had over the last 2 weeks what a singleton is and what criticisms I have of it. I have used it a few times for items such as user data (simple key-value eg. last file opened by this user) and logging (very common i'm sure). I've never ever used it just to have what is essentially global application data, as this is clearly stupid. In the first interview, I reply that I have no criticisms of it. He seemed disappointed by this but as the job wasn’t really for me, I forgot about it. In the next one, I was asked again and, as I wanted this job, I thought about it on the spot and made some objections, similar to those contained in the post linked to above (I suggested use of a factory or dependency injection instead). He seemed happy with this. But my problem is that I have used the singleton without ever using it in this kind of stupid way, which I had to describe on the spot. Using it for global data and the like isn’t something I did then realised was stupid, or read was stupid so didn’t do, it was just something I knew was stupid from the start. Essentially I’m supposed to be able to think of ways of how to misuse a pattern in the interview? Which class of programmers can best answer this question? The best ones? The medium ones? I'm not sure.... And these were both bright guys. I read more than enough to get better at my job but had never actually bothered to seek out criticisms of the most simple of the design patterns like this one. Do people think such questions are valid and that I ought to know the objections off by heart? Or that it is reasonable to be able to work out what other people who are missing the point would do on the fly? Or do you think I’m at least partially right that the question is too unsubtle and that the questions ought to be better thought out in order to make sure only good candidates can answer. PS. Please don’t think I’m saying that I’m just so clever that I know everything automatically - I’ve learnt the hard way like everyone else. But avoiding global data is hardly revolutionary.

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IPhone Development Profile Expired

- by theiphoneguy

I really combed this site and others. I read and re-read the related links here and the Apple docs. I'm sorry, but either I am obviously missing something right under my nose, or this Apple profile/certificate stuff is a bit convoluted. Here it is: I have a product in the App Store. I have updated it several times and users like it. My development profile recently expired just when I was improving the app for its next release. I can run the app in the simulator. I can compile and put the distribution build on my iPhone just fine. I went to the Apple portal and renewed the development profile. I downloaded it and installed it in Xcode. I see it in the Organize window. I see it on my iPhone. I CANNOT put the debug build on my iPhone to debug or run with Instruments. The message is that either there is not a valid signed profile or it is untrusted. I subsequently tried to download and install the certificate to my Mac's keychain. Still no success. I checked the code signing section of Project settings and also for the target and the root. All appears to indicate that it is using the expected development profile for debug. Yes, I had deleted the old profile from my iPhone, from the Organizer. I cleaned the Xcode cache and all targets. I have done all of this several times and in varying sequences to try to cover every possibility. I am ready to do anything to be able to debug with Instruments in order to check for leaks or high memory usage. Even though the distribution compile runs fine on my iPhone and plays well with other running processes, I will not release anything without a leaks/memory test. Any ideas will be appreciated. If I missed something obvious, please forgive me - it was not due to just posting a question without searching for similar postings. Thanks!

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Jquery hover function doesn't work for a table...

- by chandru_cp

I dynamically added rows to a table but it doesn't seem to take hover effects given in jquery... Here is my code, <table id="chkbox" cellpadding="0" cellspacing="2" width="100%" class="table_Style_Border"> <tr> <td style="width:150px" class="grid_header" align="center">RackName</td> <td style="width:150px" class="grid_header" align="center">LibraryName</td> <td style="width:200px" class="grid_header" align="center">LibrarianName</td> <td style="width:200px" class="grid_header" align="center">Location</td> <td style="width:1%" class="grid_header"></td> </tr> <? if(isset($comment)) { echo '<tr><td class=table_label colspan=5>'.$comment.'</td></tr>'; } ?> <?php foreach($rackData as $key => $row) { ?> <?php printf('<tr class="%s">', ($key % 2) ? 'rowcolor' : 'alternaterowcolor'); ?> <td align="left" class="table_label"> <?=$row['rack_name']?> </td> <td align="left" class="table_label"> <?=$row['library_name']?> </td> <td align="center" class="table_label"> <?=$row['librarian']?> </td> <td align="center" class="table_label"> <?=$row['location']?> </td> <td align="center"> <input type="checkbox" name="group" id="group" value="<?=$row['rack_id']?>" onclick="display(this);" > </td> </tr> <? } ?> </table><div align="right" class="pagination"> <?php /*?><?php echo $links;?><?php */?></div> <script type="text/javascript"> $("#chkbox").hover(function() { $(this).addClass("resultshover"); }, function() { $(this).removeClass("resultshover"); }); </script>

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How to add next and previous buttons to my pager row

- by eddy

Hi folks!! How would I add next/previous buttons to this snippet, cause as you can see ,it will display as many links as it needs, so if you have a high number of pages then this might not be the best solution <c:choose> <c:when test="${pages >1}"> <div class="pagination art-hiddenfield" > <c:forEach var="i" begin="1"end="${pages}" step="1"> <c:url value="MaintenanceListVehicles.htm" var="url"> <c:param name="current" value="${i}"/> </c:url> <c:if test="${i==current}"> <a href="<c:out value="${url}"/> " class="current" > <c:out value="${i}" /></a> </c:if> <c:if test="${i!=current}"> <a href="<c:out value="${url}"/> " > <c:out value="${i}" /></a> </c:if> </c:forEach> </div> </c:when> <c:otherwise> <div align="center"> </div> </c:otherwise> </c:choose> CSS: .pagination .current { background: #26B; border: 1px solid #226EAD; color: white; } .pagination a { display: block; border: 1px solid #226EAD; color: #15B; text-decoration: none; float: left; margin-bottom: 5px; margin-right: 5px; padding: 0.3em 0.5em; } .pagination { font-size: 80%; float: right; } div { display: block; } This is what I get with my current code: And this is what I'd like to display, with ellipsis if possible Hope you can help me out.

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Image_tag .blank? - paperclip - Ruby on rails

- by bgadoci

I have just installed paperclip into my ruby on rails blog application. Everything is working great...too great. I am trying to figure out how to tell paperclip not to output anything if there is no record in the table so that I don't have broken image links everywhere. How, and where, do I do this? Here is my code: class Post < ActiveRecord::Base has_attached_file :photo, :styles => { :small => "150x150"} validates_presence_of :body, :title has_many :comments, :dependent => :destroy has_many :tags, :dependent => :destroy has_many :ugtags, :dependent => :destroy has_many :votes, :dependent => :destroy belongs_to :user after_create :self_vote def self_vote # I am assuming you have a user_id field in `posts` and `votes` table. self.votes.create(:user => self.user) end cattr_reader :per_page @@per_page = 10 end View <% div_for post do %> <div id="post-wrapper"> <div id="post-photo"> <%= image_tag post.photo.url(:small) %> </div> <h2><%= link_to_unless_current h(post.title), post %></h2> <div class="light-color"> <i>Posted <%= time_ago_in_words(post.created_at) %></i> ago </div> <%= simple_format truncate(post.body, :length => 600) %> <div id="post-options"> <%= link_to "Read More >>", post %> | <%= link_to "Comments (#{post.comments.count})", post %> | <%= link_to "Strings (#{post.tags.count})", post %> | <%= link_to "Contributions (#{post.ugtags.count})", post %> | <%= link_to "Likes (#{post.votes.count})", post %> </div> </div> <% end %>

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How can I stop Flash from changing indent when user Clicks on hyperlink in TextField?

- by Paul Chernoch

I have a TextField which I initialize by setting htmlText. The text has anchor tags (hyperlinks). When a user clicks on the hyperlink, the indentation of the second and subsequent lines in the paragraph changes. Why? How do I stop it? My html has an image at the beginning of the line, followed by the tag, followed by more text. To style the hyper links to look blue always and underlined when the mouse is over them, I do this: var css:StyleSheet = new StyleSheet(); css.parseCSS("a {color: #0000FF;} a:hover {text-decoration: underline;}"); stepText.styleSheet = css; stepText.htmlText = textToUse; stepText.visible = true; Here is a fragment of the html text (with newlines and exrta whitespace added to improve readability - originally it was one long line): <textformat indent="-37" blockindent="37" > <img src="media/interface/level-1-bullets/solid-circle.png" align="left" hspace="8" vspace="1"/> American Dental Association. (n.d.). <i>Cleaning your teeth and gums (oral hygiene)</i>. Retrieved 11/24/08, from <a href="http://www.ada.org/public/topics/cleaning_faq.asp" target="_blank">http://www.ada.org/public/topics/cleaning_faq.asp </a> </textformat> <br/> As it turns out, the text field is of a width such that it wraps and the second line starts with "Retrieved 11/24/08". Clicking on the hyper link causes this particular line to be indented. Subsequent paragraphs are not affected. ASIDE: The image is a list bullet about 37 pixels wide. (I used images instead of li tags because Flash does not allow nested lists, so I faked it using a series of images with varying amounts of whitespace to simulate three levels of indentation.) IDEA: I was thinking of changing all hyperlinks to use "event:" as the URL protocol, which causes a TextEvent.LINK event to be triggered instead of following the link. Then I would have to open the browser in a second call. I could use this event handler to set the html text to itself, which might clear the problem. (When I switch pages in my application and then come back to the page, everything is OKAY again.) PROBLEM: If I use the "event:" protocol and user tries the right-mouse button click, they will get an error, or so I am told. (See http://www.blog.lessrain.com/as3-texteventlink-and-contextmenu-incompatibilities/ ) I do not like this trade-off.

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Linking two models in a multi-model form

- by Elliot

Hey Guys, I have a nested multimodel form right now, using Users and Profiles. Users has_one profile, and Profile belongs_to Users. When the form is submitted, a new user is created, and a new profile is created, but they are not linked (this is the first obvious issue). The user's model has a profile_id row, and the profile's model has a user_id row. Here is the code for the form: <%= form_for(@user, :url => teams_path) do |f| %> <p><%= f.label :email %><br /> <%= f.text_field :email %></p> <p><%= f.label :password %><br /> <%= f.password_field :password %></p> <p><%= f.label :password_confirmation %><br /> <%= f.password_field :password_confirmation %></p> <%= f.hidden_field :role_id, :value => @role.id %></p> <%= f.hidden_field :company_id, :value => current_user.company_id %></p> <%= fields_for @user.profile do |profile_fields| %> <div class="field"> <%= profile_fields.label :first_name %><br /> <%= profile_fields.text_field :first_name %> </div> <div class="field"> <%= profile_fields.label :last_name %><br /> <%= profile_fields.text_field :last_name %> </div> <% end %> <p><%= f.submit "Sign up" %></p> <% end %> A second issue, is even though the username, and password are successfully created through the form for the user model, the hidden fields (role_id & company_id - which are also links to other models) are not created (even though they are part of the model) - the values are successfully shown in the HTML for those fields however. Any help would be great!

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How to get colliding effect or bouncy when ball hits the track.

- by Chandan Shetty SP

I am using below formula to move the ball circular, where accelX and accelY are the values from accelerometer, it is working fine. But the problem in this code is mRadius (I fixed its value to 50), i need to change mRadius according to accelerometer values and also i need bouncing effect when it touches the track. Currently i am developing code by assuming only one ball is on the board. float degrees = -atan2(accelX, accelY) * 180 / 3.14159; int x = cCentrePoint.x + mRadius * cos(degreesToRadians(degrees)); int y = cCentrePoint.y + mRadius * sin(degreesToRadians(degrees)); Here is the snap of the game i want to develop: Updated: I am sending the updated code... mRadius = 5; mRange = NSMakeRange(0,60); -(void) updateBall: (UIAccelerationValue) accelX withY:(UIAccelerationValue)accelY { float degrees = -atan2(accelX, accelY) * 180 / 3.14159; int x = cCentrePoint.x + mRadius * cos(degreesToRadians(degrees)); int y = cCentrePoint.y + mRadius * sin(degreesToRadians(degrees)); //self.targetRect is rect of ball Object self.targetRect = CGRectMake(newX, newY, 8, 9); self.currentRect = self.targetRect; //http://books.google.co.in/books?id=WV9glgdrrrUC&pg=PA455#v=onepage&q=&f=false static NSDate *lastDrawTime; if(lastDrawTime!=nil) { NSTimeInterval secondsSinceLastDraw = -([lastDrawTime timeIntervalSinceNow]); ballXVelocity = ballXVelocity + (accelX * secondsSinceLastDraw) * [self isTouchedTrack:mRadius andRange:mRange]; ballYVelocity = ballYVelocity + -(accelY * secondsSinceLastDraw) * [self isTouchedTrack:mRadius andRange:mRange]; distXTravelled = distXTravelled + secondsSinceLastDraw * ballXVelocity * 50; distYTravelled = distYTravelled + secondsSinceLastDraw * ballYVelocity * 50; CGRect temp = self.targetRect; temp.origin.x += distXTravelled; temp.origin.y += distYTravelled; int radius = (temp.origin.x - cCentrePoint.x) / cos(degreesToRadians(degrees)); if( !NSLocationInRange(abs(radius),mRange)) { //Colided with the tracks...Need a better logic here ballXVelocity = -ballXVelocity; } else { // Need a better logic here self.targetRect = temp; } //NSLog(@"angle = %f",degrees); } [lastDrawTime release]; lastDrawTime = [ [NSDate alloc] init]; } In the above code i have initialized mRadius and mRange(indicate track) to some constant for testing, i am not getting the moving of the ball as i expected( bouncing effect when Collided with track ) with respect to accelerometer. Help me to recognize where i went wrong or send some code snippets or links which does the similar job. I am searching for better logic than my code, if you found share with me.

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Issues in Ajax based applications

- by Sinuhe

I'm very interested in developing Ajax based applications. This is, loading almost all of the content of the application via XMLHttpRequest, instead of only some combos and widgets. But if I try to do this form scratch, soon I find some problems without an easy solution. I wonder if there is some framework (both client and server side) to deal with this issues. As far as I know, there isn't (but I've searched mainly in Java world). So I am seriously thinking of doing my own framework, at least for my projects. Therefore, in this question I ask for several things. First, the possible problems of an ajax based development. Then, I'm looking for some framework or utility in order to deal with them. Finally, if there is no framework available, what features must it have. Here are the issues I thought: 1 - JavaScript must be enabled. Security paranoia isn't the only problem: a lot of mobile devices couldn't use the application, too. 2 - Sometimes you need to update more than one DIV (e.g. main content, menu and breadcrumbs). 3 - Unknown response type: when you make an Ajax call, you set the callback function too, usually specifying if expected response is a javascript object or in which DIV put the result. But this fails when you get another type of response: for example when the session has expired and the user must log in again. 4 - Browser's refresh, back and forward buttons can be a real pain. User will expect different behaviors depending on the situation. 5 - When search engines indexes a site, only follow links. Thus, content load by Ajax won't "exist" for who doesn't know about it yet. 6 - Users can ask for open a link in a different window/tab. 7 - Address bar doesn't show the "real" page you are in. So, you can't copy the location and send it to a friend or bookmark the page. 8 - If you want to monetize the site, you can put some advertisings. As you don't refresh entire page and you want to change the ad after some time, you have to refresh only the DIV where the ad is. But this can violate the Terms and Conditions of your ad service. In fact, it can go against AdSense TOS. 9 - When you refresh an entire page, all JavaScript gets "cleaned". But in Ajax calls, all JavaScript objects will remain. 10 - You can't easily change your CSS properties.

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Jquery-UI tabs : Double loading of the default tab with

- by Stephane

I use jqueryui-tabs to display a tabbed UI. here is how my markup looks in a MasterPage: <div id="channel-tabs" class="ui-tabs"> <ul class="ui-tabs-nav"> <li><%=Html.ActionLink("Blogs", "Index", "Blog", new { query = Model.Query, lang = Model.SelectedLanguage, fromTo = Model.FromTo, filters = Model.FilterId }, new{ title="Blog Results" }) %></li> <li><%=Html.ActionLink("Forums", "Index", "Forums", new { query = Model.Query, lang = Model.SelectedLanguage, fromTo = Model.FromTo, filters = Model.FilterId }, null) %></li> <li><%=Html.ActionLink("Twitter", "Index", "Twitter", new { query = Model.Query, lang = Model.SelectedLanguage, fromTo = Model.FromTo, filters = Model.FilterId }, null) %></li> </ul> <div id="Blog_Results"> <asp:ContentPlaceHolder ID="ResultPlaceHolder" runat="server"> </asp:ContentPlaceHolder> </div> If the content is loaded via ajax, I return a partial view with the content of the tab. If the content is loaded directly, I load a page that include the content in the ContentPlaceHolder. somewhat like this : <asp:Content ID="Content2" ContentPlaceHolderID="BlogPlaceHolder" runat="server"> <%=Html.Partial("Partial",Model) %> </asp:Content> //same goes for the other tabs. With this in place, if I access the url "/Forums" It loads the forum content in the Blog tab first, trigger the ajax load of the Blog tab and replace the content with the blog content. I tried putting a different placeholder for each tab, but that didn't fix everything either, since when loading "/Forums" it will sure load the forum tab, but the Blog tab will show up first. Furthermore, when using separate placeholders, If I load the "/Blogs" url, It will first load the content statically in the Blog contentplaceholder and then trigger an ajax call to load it a second time and replace it. If I just link the tab to the hashtag, then when loading the forum tabs, I won't get the blog content... How would you achieve the expected behaviour? I feel like I might have a deeper probelm in the organization of my views. Is putting the tabs in the masterpage the way to go? Maybe I should just hijax the links manually and not rely on jquery-ui tabs to do the work for me. I cannot load all tabs by default and display them using the hash tags, I need an ajax loading because it is a search process that can be long. So to sum up : /Forum should load the forum tab, and let the other tabs be loaded with an ajax call when clicking on it. /Twitter should load the twitter tab and let the other tabs.... the same goes for /Blogs and any tabs I would add later.

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Does CakePHP treat all INT fields as ID's for join tables?

- by Jonnie

I am trying to save a User, their Profile, and some tags and my join table that links the profile and the tags keeps getting messed up. The profile model is called Instructor, the tag model is called Subject. The Instructor has a phone number and a zip code and for some reason CakePHP thinks these are the fields it should use when creating entries in my join table. My Join table always comes out as: id | instructor_id | subject_id | 1 | 90210 | 1 | // thinks that the zip code is an instructor_id 2 | 1112223333 | 1 | // thinks that the phone number is an instructor_id 3 | 1 | 1 | // thinks that user_id is an instructor_id 4 | 1 | 1 | // the actual instructor_id, this one's correct 5 | 90210 | 2 | 6 | 1112223333 | 2 | 3 | 1 | 2 | 4 | 1 | 2 | My Models: class Instructor extends AppModel { var $name = 'Instructor'; var $belongsTo = array('User', 'State'); var $hasAndBelongsToMany = array( 'Subject' = array( 'className' = 'Subject', 'joinTable' = 'instructors_subjects', 'foreignKey' = 'instructor_id', 'associationForeignKey' = 'subject_id', 'unique' = true, 'conditions' = '', 'fields' = '', 'order' = '', 'limit' = '', 'offset' = '', 'finderQuery' = '', 'deleteQuery' = '', 'insertQuery' = '' ) ); } class Subject extends AppModel { var $name = 'Subject'; var $hasAndBelongsToMany = array( 'Instructor' = array( 'className' = 'Instructor', 'joinTable' = 'instructors_subjects', 'foreignKey' = 'subject_id', 'associationForeignKey' = 'instructor_id', 'unique' = true, 'conditions' = '', 'fields' = '', 'order' = '', 'limit' = '', 'offset' = '', 'finderQuery' = '', 'deleteQuery' = '', 'insertQuery' = '' ) ); } My Model Associations: User hasOne Instructor Instructor belongsTo User Instructor hasAndBelongsToMany Subject Subject hasAndBelongsToMany Instructor My form data looks like: Array ( [User] = Array ( [username] = MrInstructor [password] = cddb06c93c72f34eb9408610529a34645c29c55d [group_id] = 2 ) [Instructor] = Array ( [name] = Jimmy Bob [email] = [email protected] [phone] = 1112223333 [city] = Beverly Hills [zip_code] = 90210 [states] = 5 [website] = www.jimmybobbaseballschool.com [description] = Jimmy Bob is an instructor. [user_id] = 1 [id] = 1 ) [Subject] = Array ( [name] = hitting, pitching ) ) My function for processing the form looks like: function instructor_register() { $this-set('groups', $this-User-Group-find('list')); $this-set('states', $this-User-Instructor-State-find('list')); if (!empty($this-data)) { // Set the group to Instructor $this-data['User']['group_id'] = 2; // Save the user data $user = $this-User-save($this-data, true, array( 'username', 'password', 'group_id' )); // If the user was saved, save the instructor's info if (!empty($user)) { $this-data['Instructor']['user_id'] = $this-User-id; $instructor = $this-User-Instructor-save($this-data, true, array( 'user_id', 'name', 'email', 'phone', 'city', 'zip_code', 'state_id', 'website', 'description' )); // If the instructor was saved, save the rest if(!empty($instructor)) { $instructorId = $this-User-Instructor-id; $this-data['Instructor']['id'] = $instructorId; // Save each subject seperately $subjects = explode(",", $this-data['Subject']['name']); foreach ($subjects as $_subject) { // Get the correct subject format $_subject = strtolower(trim($_subject)); $this-User-Instructor-Subject-create($this-data); $this-User-Instructor-Subject-set(array( 'name' = $_subject )); $this-User-Instructor-Subject-save(); echo ''; print_r($this-data); echo ''; } } } } }

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