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  • Memory management in Qt?

    - by Martin
    I'm quite new to Qt and am wondering on some basic stuff with memory management and the life of objects. When do I need to delete / destroy my objects? Is any of this handled automatically? In the example below, which of the objects I create do I need to delete? What happens to the instance variable myOtherClass when myClass is destroyed? What happens if I don't delete / destroy my objects at all, will that be a problem to memory? in MyClass.h: class MyClass { public: MyClass(); ~MyClass(); MyOtherClass *myOtherClass; }; in MyClass.cpp: MyClass::MyClass() { myOtherClass = new MyOtherClass(); MyOtherClass myOtherClass2; QString myString = "Hello"; } As you can see this is quite newbie-easy stuff but where can I learn about this in an easy way? Thanks really much

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  • What is a Windows scripting language that: does not rely on .NET and offers the most OOP support and

    - by jJack
    What is a Windows scripting language that: does not rely on .NET and offers the most OOP support and has simplest deployment? It doesn't necessarily need to be a scripting language; It can be in the form of a compiled executable, however it needs to be self contained--only ONE file, no DLL's and it cannot be declared to "include" other files. I cannot rely on the user having any .NET installed and it needs to be able to run on Windows 7 64 bit. By "most OOP support", I basically mean anything that has better OOP support than VBScript. A little context: Everything I have done thus far is in VBScript and writes a bunch of data into an .html file, which in the end is to be viewed by Internet Explorer. It also zips up a bunch of directories and files. It heavily relies on accessing the registry, file-system, and WMI (I can probably do without accessing WMI though, as long as I have good registry access). I can bring myself to code in any language so long as it meets me ridonkulous requirements stated above. I look forward to some good answers from those more experienced than I.

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  • How can "set timestamp" be a slow query?

    - by Peder
    My slow query log is full of entries like the following # Query_time: 1.016361 Lock_time: 0.000000 Rows_sent: 0 Rows_examined: 0 SET timestamp=1273826821; COMMIT; I guess the set timestamp command is issued by replication but I don't understand how set timestamp can take over a second. Any ideas?

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  • Using TCP Acks to measure latency to a server?

    - by Ted Graham
    I am trying to measure latency to a server that I don't control. This is in a colocated environment, so the latency is on the order of 500 us (.5 ms). I understand that Cisco gear frequently deprioritizes ICMP traffic, making ping times unreliable. Is there a way for me to tell if this is the case on the gear I am traversing? Can I use TCP acknowledgements to determine the minimum latency to the remote server? To do this, I would somehow need to force the remote server to send a TCP ack immediately on receiving my data.

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  • How can I make this Java code run faster?

    - by Martin Wiboe
    Hello all, I am trying to make a Java port of a simple feed-forward neural network. This obviously involves lots of numeric calculations, so I am trying to optimize my central loop as much as possible. The results should be correct within the limits of the float data type. My current code looks as follows (error handling & initialization removed): /** * Simple implementation of a feedforward neural network. The network supports * including a bias neuron with a constant output of 1.0 and weighted synapses * to hidden and output layers. * * @author Martin Wiboe */ public class FeedForwardNetwork { private final int outputNeurons; // No of neurons in output layer private final int inputNeurons; // No of neurons in input layer private int largestLayerNeurons; // No of neurons in largest layer private final int numberLayers; // No of layers private final int[] neuronCounts; // Neuron count in each layer, 0 is input // layer. private final float[][][] fWeights; // Weights between neurons. // fWeight[fromLayer][fromNeuron][toNeuron] // is the weight from fromNeuron in // fromLayer to toNeuron in layer // fromLayer+1. private float[][] neuronOutput; // Temporary storage of output from previous layer public float[] compute(float[] input) { // Copy input values to input layer output for (int i = 0; i < inputNeurons; i++) { neuronOutput[0][i] = input[i]; } // Loop through layers for (int layer = 1; layer < numberLayers; layer++) { // Loop over neurons in the layer and determine weighted input sum for (int neuron = 0; neuron < neuronCounts[layer]; neuron++) { // Bias neuron is the last neuron in the previous layer int biasNeuron = neuronCounts[layer - 1]; // Get weighted input from bias neuron - output is always 1.0 float activation = 1.0F * fWeights[layer - 1][biasNeuron][neuron]; // Get weighted inputs from rest of neurons in previous layer for (int inputNeuron = 0; inputNeuron < biasNeuron; inputNeuron++) { activation += neuronOutput[layer-1][inputNeuron] * fWeights[layer - 1][inputNeuron][neuron]; } // Store neuron output for next round of computation neuronOutput[layer][neuron] = sigmoid(activation); } } // Return output from network = output from last layer float[] result = new float[outputNeurons]; for (int i = 0; i < outputNeurons; i++) result[i] = neuronOutput[numberLayers - 1][i]; return result; } private final static float sigmoid(final float input) { return (float) (1.0F / (1.0F + Math.exp(-1.0F * input))); } } I am running the JVM with the -server option, and as of now my code is between 25% and 50% slower than similar C code. What can I do to improve this situation? Thank you, Martin Wiboe

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  • JAX-WS returning a complex object?

    - by occhiso
    Hi, Im pretty new to Java Web Services, but I cant find a good explanation anywhere. I have 2 Java web projects within NetBeans. One as a web service and one as a client for that web service. I have also created my own class called "Person", which has what you'd expect: name, dob, etc. I would like to have a web service method called "ListPeople()" that would return an array of "Person" objects. Do I need to have that class in both projects? Should I be serializing the object first? Should I be using JAXB, if so, where do I start? Sorry for the n00b questions, but im confused. What is the normal way of accomplishing this? Thanks in advance

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  • Mysql: Perform of NOT EXISTS. Is it possible to improve permofance?

    - by petRUShka
    I have two tables posts and comments. Table comments have post_id attribute. I need to get all posts with type "open", for which there are no comments with type "good" and created date MAY 1. Is it optimal to use such SQL-query: SELECT posts.* FROM posts WHERE NOT EXISTS ( SELECT comments.id FROM comments WHERE comments.post_id = posts.id AND comments.comment_type = 'good' AND comments.created_at BETWEEN '2010-05-01 00:00:00' AND '2010-05-01 23:59:59') I'm not sure that NOT EXISTS is perfect construction in this situation.

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  • Entity Framework - refresh objects from database

    - by Nebo
    I'm having trouble with refreshing objects in my database. I have an two PC's and two applications. On the first PC, there's an application which communicates with my database and adds some data to Measurements table. On my other PC, there's an application which retrives the latest Measurement under a timer, so it should retrive measurements added by the application on my first PC too. The problem is it doesn't. On my application start, it caches all the data from database and never get new data added. I use Refresh() method which works well when I change any of the cached data, but it doesn't refresh newly added data. Here is my method which should update the data: public static Entities myEntities = new Entities(); public static Measurement GetLastMeasurement(int conditionId) { myEntities.Refresh(RefreshMode.StoreWins, myEntities.Measurements); return (from measurement in myEntities.Measurements where measurement.ConditionId == conditionId select measurement).OrderByDescending(cd => cd.Timestamp).First(); } P.S. Applications have different connection strings in app.config (different accounts for the same DB).

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  • F#: Define an abstract class that inherits an infterface, but does not implement it

    - by akaphenom
    I owuld like to define an abstract class that inerhits from UserControl and my own Interface IUriProvider, but doesn't implement it. The goal is to be able to define pages (for silverlight) that implement UserControl but also provide their own Uri's (and then stick them in a list / array and deal with them as a set: type IUriProvider = interface abstract member uriString: String ; abstract member Uri : unit -> System.Uri ; end type UriUserControl() as this = inherit IUriProvider with abstract member uriString: String ; inherit UserControl() Also the Uri in the definition - I would like to implement as a property getter - and am having issues with that as well. this does not compile type IUriProvider = interface abstract member uriString: String with get; end Thank you...

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  • Server Benchmarking: What tools to use with my real-world test data

    - by mdemmitt
    I want to benchmark a new server using historical HTTP-request data. I have a textfile that contains one day's worth of real historical requests to a production server. What is the best tool for sending that list of requests on the server I'm testing? The tool I use should be able to configure the following: Number of threads making the requests Number of requests/second sent A list of request URLs to use when making the requests. Apache Bench seems like a close fit. However, Bench does not seem to be able to take in a list of request URLs as a parameter. What would you recommend?

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  • Python: Recursively access dict via attributes as well as index access?

    - by Luke Stanley
    I'd like to be able to do something like this: from dotDict import dotdictify life = {'bigBang': {'stars': {'planets': [] } } } dotdictify(life) #this would be the regular way: life['bigBang']['stars']['planets'] = {'earth': {'singleCellLife': {} }} #But how can we make this work? life.bigBang.stars.planets.earth = {'singleCellLife': {} } #Also creating new child objects if none exist, using the following syntax life.bigBang.stars.planets.earth.multiCellLife = {'reptiles':{},'mammals':{}} My motivations are to improve the succinctness of the code, and if possible use similar syntax to Javascript for accessing JSON objects for efficient cross platform development.(I also use Py2JS and similar.)

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  • Are Hibernate named HQL queries (in annotations) optimised?

    - by Graham Lea
    A new colleague has just suggested using named HQL queries in Hibernate with annotations (i.e. @NamedQuery) instead of embedding HQL in our XxxxRepository classes. What I'd like to know is whether using the annotation provides any advantage except for centralising quueries? In particular, is there some performances gain, for instance because the query is only parsed once when the class is loaded rather than every time the Repository method is executed?

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  • How to efficiently show many Images? (iPhone programming)

    - by Thomas
    In my application I needed something like a particle system so I did the following: While the application initializes I load a UIImage laserImage = [UIImage imageNamed:@"laser.png"]; UIImage *laserImage is declared in the Interface of my Controller. Now every time I need a new particle this code makes one: // add new Laserimage UIImageView *newLaser = [[UIImageView alloc] initWithImage:laserImage]; [newLaser setTag:[model.lasers count]-9]; [newLaser setBounds:CGRectMake(0, 0, 17, 1)]; [newLaser setOpaque:YES]; [self.view addSubview:newLaser]; [newLaser release]; Please notice that the images are only 17px * 1px small and model.lasers is a internal array to do all the calculating seperated from graphical output. So in my main drawing loop I set all the UIImageView's positions to the calculated positions in my model.lasers array: for (int i = 0; i < [model.lasers count]; i++) { [[self.view viewWithTag:i+10] setCenter:[[model.lasers objectAtIndex:i] pos]]; } I incremented the tags by 10 because the default is 0 and I don't want to move all the views with the default tag. So the animation looks fine with about 10 - 20 images but really gets slow when working with about 60 images. So my question is: Is there any way to optimize this without starting over in OpenGl ES? Thank you very much and sorry for my english! Greetings from Germany, Thomas

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  • KD-Trees and missing values (vector comparison)

    - by labratmatt
    I have a system that stores vectors and allows a user to find the n most similar vectors to the user's query vector. That is, a user submits a vector (I call it a query vector) and my system spits out "here are the n most similar vectors." I generate the similar vectors using a KD-Tree and everything works well, but I want to do more. I want to present a list of the n most similar vectors even if the user doesn't submit a complete vector (a vector with missing values). That is, if a user submits a vector with three dimensions, I still want to find the n nearest vectors (stored vectors are of 11 dimensions) I have stored. I have a couple of obvious solutions, but I'm not sure either one seem very good: Create multiple KD-Trees each built using the most popular subset of dimensions a user will search for. That is, if a user submits a query vector of thee dimensions, x, y, z, I match that query to my already built KD-Tree which only contains vectors of three dimensions, x, y, z. Ignore KD-Trees when a user submits a query vector with missing values and compare the query vector to the vectors (stored in a table in a DB) one by one using something like a dot product. This has to be a common problem, any suggestions? Thanks for the help.

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  • data sync from rails with iphone sqlite db

    - by Markus
    Hi all, I'm wondering whether there is a bossibility to export some selected data from my rails mysql db to a other sqlite db. The aim is to send that sqlite file directly to my iPhone application... That way I don't have to do a lot of xml integration in the iPhone app. That seems to be very slow... Markus

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  • SQL Server Multiple Joins Are Taxing The CPU

    - by durilai
    I have a stored procedure on SQL Server 2005. It is pulling from a Table function, and has two joins. When the query is run using a load test it kills the CPU 100% across all 16 cores! I have determined that removing one of the joins makes the query run fine, but both taxes the CPU. Select SKey From dbo.tfnGetLatest(@ID) a left join [STAGING].dbo.RefSrvc b on a.LID = b.ESIID left join [STAGING].dbo.RefSrvc c on a.EID = c.ESIID Any help is appreciated, note the join is happening on the same table in a different database on the same server.

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  • Where should Nhibernate IPostInsertEventListener go in the 3 tier architecture

    - by Quintin Par
    I have a IPostInsertEventListener implementation like public class NHibernateEventListener : IPostInsertEventListener, IPostUpdateEventListener which catches some entity inserts and does an additional insert to another table for ETL. Essentially it requires references to the Nhibernate, Domain entity and Repository<> Now where do I go about adding this class? If I add it to ApplicationServices I’ll end up referencing Nhibernate at that layer. If I add this to the Data layer, I’ll have to reference Domain (circular). How do I go implementing this class with S#arp principles? Any thoughts?

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  • How to access the subject of a compose mail item in Outlook

    - by vwfreak034
    In Outlook, I can set the subject for a new message (when composing a new mail message), but I want to prepend text. So I need to get the subject first, and then set it. Outlook.Application application = Globals.ThisAddIn.Application; Outlook.Inspector inspector = application.ActiveInspector(); Outlook.MailItem myMailItem = (Outlook.MailItem)inspector.CurrentItem; if (myMailItem != null && !string.IsNullOrEmpty(myMailItem.Subject)) { myMailItem.Subject = "Following up on your order"; } This code works on replies, but not for new messages, because in that case, myMailItem is null.

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  • JavaScript: using constructor without operator 'new'

    - by GetFree
    Please help me to understand why the following code works: <script> var re = RegExp('\\ba\\b') ; alert(re.test('a')) ; alert(re.test('ab')) ; </script> In the first line there is no new operator. As far as I know, a contructor in JavaScript is a function that initialize objects created by the operator new and they are not meant to return anything.

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  • Looking for Suggestion on Multi-Consumer Service Development

    - by DaveDev
    How would I model a system that needs to be able to provide content in a format that would be consumable by iphone, Android or web browser (or whatever). All a new consumer would have to do is build a UI with rules on how to handle the data. I'm thinking something RESTful returning JSON or something. I'm really looking for suggestions on the kinds of things I'd need to learn in order to be able to implement a system on this scale. As an ASP.NET MVC developer, would that be the best framework/archetectrue to go with? Thanks

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  • Conditional relation

    - by Lowgain
    I've got a model like this: Stem -id -etc And then I have Stemrelation -stem_id -related_stem_id -active I can get the related stems with the following relations class Stem < ActiveRecord::Base has_many :stemrelations has_many :related_stems, :through => :stemrelations end class Stemrelation < ActiveRecord::Base belongs_to :stem belongs_to :related_stem, :class_name => "Stem", :foreign_key => "related_stem_id" end But now I'd only like to get the active relations. I tried adding this to the Stem model: has_many :active_related, :through => :stemrelations, :source => :related_stem, :conditions => {:active => true} but this gives me an error becasue it tries to check the active flag on the stem model instead of the stemrelation. What do I change here? Thanks!

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  • How can I get page faults statistics from kernel

    - by osgx
    Hello How can I get page faults statistics from kernel for my application while it is running? What about other events, like inter-cpu migrations count in SMP nodes, or number of context switches? I want to count such events for various small parts of the program. Thanks.

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  • How to calculate real-time stats?

    - by Diego Jancic
    I have a site with millions of users (well, actually it doesn't have any yet, but let's imagine), and I want to calculate some stats like "log-ins in the past hour". The problem is similar to the one described here: http://highscalability.com/blog/2008/4/19/how-to-build-a-real-time-analytics-system.html The simplest approach would be to do a select like this: select count(distinct user_id) from logs where date>='20120601 1200' and date <='20120601 1300' (of course other conditions could apply for the stats, like log-ins per country) Of course this would be really slow, mainly if it has millions (or even thousands) of rows, and I want to query this every time a page is displayed. How would you summarize the data? What should go to the (mem)cache? EDIT: I'm looking for a way to de-normalize the data, or to keep the cache up-to-date. For example I could increment an in-memory variable every time someone logs in, but that would help to know the total amount of logins, not the "logins in the last hour". Hope it's more clear now.

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  • What happens to an ActiveX control (COleControl) after the call to OnDestroy() ?

    - by richj
    I have an ActiveX control written in C++ that runs in Internet Explorer 8. Most of the time (approx 90%) when the tab or browser containing the control is closed, there is an access violation like this: The thread 'Win32 Thread' (0x1bf0) has exited with code 0 (0x0). Unhandled exception at 0x77b3b9fd in iexplore.exe: 0xC0000005: Access violation reading location 0x65007408. The access violation occurs after the call to OnDestroy() but before the call to the control's destructor. The debug output says: No symbols are loaded for any call stack frame. The source code cannot be displayed. None of my code is present in the stacktrace, although perhaps the heap was corrupted at some earlier point during execution. What lifecycle events does an ActiveX control receive between the call to OnDestroy() and the control's destructor?

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