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  • Jboss 6 Cluster Singleton Clustered

    - by DanC
    I am trying to set up a Jboss 6 in a clustered environment, and use it to host clustered stateful singleton EJBs. So far we succesfully installed a Singleton EJB within the cluster, where different entrypoints to our application (through a website deployed on each node) point to a single environment on which the EJB is hosted (thus mantaining the state of static variables). We achieved this using the following configuration: Bean interface: @Remote public interface IUniverse { ... } Bean implementation: @Clustered @Stateful public class Universe implements IUniverse { private static Vector<String> messages = new Vector<String>(); ... } jboss-beans.xml configuration: <deployment xmlns="urn:jboss:bean-deployer:2.0"> <!-- This bean is an example of a clustered singleton --> <bean name="Universe" class="Universe"> </bean> <bean name="UniverseController" class="org.jboss.ha.singleton.HASingletonController"> <property name="HAPartition"><inject bean="HAPartition"/></property> <property name="target"><inject bean="Universe"/></property> <property name="targetStartMethod">startSingleton</property> <property name="targetStopMethod">stopSingleton</property> </bean> </deployment> The main problem for this implementation is that, after the master node (the one that contains the state of the singleton EJB) shuts down gracefuly, the Singleton's state is lost and reset to default. Please note that everything was constructed following the JBoss 5 Clustering documents, as no JBoss 6 documents were found on this subject. Any information on how to solve this problem or where to find JBoss 6 documention on clustering is appreciated.

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  • Which book should I pick to improve my program designs/design patterns?

    - by zxcvbnm
    I want to learn about design patterns and from what I've seen the most recommended ones are the Gang of Four's Design Patterns and Head First Design Patterns. There are also language specific books, but I never see them recommended. I suppose it ties you to whatever strengths/weaknesses are inherent to each language, so not a good idea to learn design patterns in general. The Gang of Four's book is kinda old, so I'm wondering if there isn't a better alternative out today? I've heard the Heard First one isn't quite as good. But I'm not sure why, so it's really hard to pick either one. I've see some answers on this very site recommending both, but if I can only read one, which should I pick? I've been coding for 3+ years, though I've never had a good class on this subject. Also, would a book like Code Complete help me with this? One more thing: how often are these techniques supposed to be useful? For example, this question has me wondering if this stuff is worth the trouble. And please, tell me more than just "read x". I'd like to know why you're suggesting x.

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  • C++ Program Flow: Sockets in an Object and the Main Function

    - by jfm429
    I have a rather tricky problem regarding C++ program flow using sockets. Basically what I have is this: a simple command-line socket server program that listens on a socket and accepts one connection at a time. When that connection is lost it opens up for further connections. That socket communication system is contained in a class. The class is fully capable of receiving the connections and mirroring the data received to the client. However, the class uses UNIX sockets, which are not object-oriented. My problem is that in my main() function, I have one line - the one that creates an instance of that object. The object then initializes and waits. But as soon as a connection is gained, the object's initialization function returns, and when that happens, the program quits. How do I somehow wait until this object is deleted before the program quits? Summary: main() creates instance of object Object listens Connection received Object's initialization function returns main() exits (!) What I want is for main() to somehow delay until that object is finished with what it's doing (aka it will delete itself) before it quits. Any thoughts?

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  • Most cost effective way to target multiple mobile platforms

    - by niidto
    Hi I have been given the tasks of speccing a mobile application, which will need to run on approx. 1000 devices. These devices already exist, and consist of iPhones, BlackBerrys, Androids, Windows Mobile and Netbooks. The application will have simple reporting capability, and a collection of forms. Anyway, the obvious solution would be to develop some browser based solution, although given the occasionally connected nature of the devices, there's a potential for data to get lost / not saved. So instead of creating a complex application for each platform, I was thinking we could build what is effectively a form generator, with basic offline storage capability (text files), designed to run on each device, and have the device generate a form, based on for example an XML file that it could request from a server somewhere, resulting in minimal specialist development costs, and the ability to run most of the logic from the server end, with the devices being dumb clients that render forms and upload the data when there is an available connection. Anyway, my question summarised is, how have you made the decision on supporting multiple devices for your application. Is this always an unavoidable problem, and you just have to make the call to support 1 or 2, or pay for developers to write code for each platform, or alternatively supply pre-installed devices to the company? Many thanks James

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  • Controlling shell command line wildcard expansion in C or C++

    - by Adrian McCarthy
    I'm writing a program, foo, in C++. It's typically invoked on the command line like this: foo *.txt My main() receives the arguments in the normal way. On many systems, argv[1] is literally *.txt, and I have to call system routines to do the wildcard expansion. On Unix systems, however, the shell expands the wildcard before invoking my program, and all of the matching filenames will be in argv. Suppose I wanted to add a switch to foo that causes it to recurse into subdirectories. foo -a *.txt would process all text files in the current directory and all of its subdirectories. I don't see how this is done, since, by the time my program gets a chance to see the -a, then shell has already done the expansion and the user's *.txt input is lost. Yet there are common Unix programs that work this way. How do they do it? In Unix land, how can I control the wildcard expansion? (Recursing through subdirectories is just one example. Ideally, I'm trying to understand the general solution to controlling the wildcard expansion.)

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  • Facebook Application with PHP running losing session

    - by ArneRie
    Iam trying to build an Facebook Application based on PHP. The Application is running under php on my own Webhost inside an Canvas as iFrame. I have included the newest Client Library for PHP from Facebook: facebook-php-sdk-94fcb13 To Authorize the user inside my application iam trying to use Facebook Connect, like the example shipped with the Client. Everything works fine the 1st Login, but when i hit the F5 Key to reload the page, the session is lost and i have to login again. When i call my application outside of the Facebook Canvas everything is fine. Iam not sure, but i think my Browser (Chrome/FireFox - Ubuntu) is not allowing to store an cookie inside an iFrame. Does someone knows an solution for this Problem? Here are some Parts of the Sourcecode: $facebook = new Facebook(array( 'appId' => 'x', 'secret' => 'x', 'cookie' => 'true', )); $session = $facebook->getSession(); $facebook->setSession($session); $me = null; // Session based API call. if ($session) { try { $uid = $facebook->getUser(); $me = $facebook->api('/me'); } catch (FacebookApiException $e) { error_log($e); } } // login or logout url will be needed depending on current user state. if ($me) { $logoutUrl = $facebook->getLogoutUrl(); } else { $loginUrl = $facebook->getLoginUrl(); }

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  • How to solve the delay problem in animation of sprites ?

    - by srikanth rongali
    My problem is, I did coding for a sprite. It should change it should change it's image from( 1, 2, 3). It should look like count down time to start a game. 1, 2, 3 are 3 png images. But the images are not displayed in equal intervals of time. I mean time between (1 - 2), (2 - 3) is not same. It is random. Please help me with my problem. Help me if there is better solution than what I am doing.(My animation should be like, before any game starts we see count down 1 then 2 then 3 then GO). -(id)init { if((self = [super init])) { [[CCDirector sharedDirector] setAnimationInterval:60.0/60]; [[CCDirector sharedDirector] setDisplayFPS:NO]; CCAnimation* numberAnimation = [CCAnimation animationWithName:@"countDown" delay: 60.0/60]; for( int i=1;i<4;i++) [numberAnimation addFrameWithFilename: [NSString stringWithFormat:@"number_%02d.png", i]]; id numberAction = [CCAnimate actionWithAnimation: numberAnimation restoreOriginalFrame:NO]; id action2 = [CCFadeOut actionWithDuration:0.5f]; CCSprite *number; number = [CCSprite spriteWithFile:@"number.png"]; .... } }

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  • [C#]Update Datatable and DatagridView with database Changes by Timer

    - by aleroot
    Scenario : i have a database table that is being apdated frequently bey some services. I have a c# Winform Application that load this table in a datagridview by binding a datatable as Datasource, then i whant to add a Timer that every 10 seconds update a the content of a datatable with the last changes in the database table ... I don't need to update a database with the datatable changes, but i need to update datatable with the last changes in the database table, that is the inverse of the usually.... Is there a way to do that ? What is the best way ? i've tried with this code : private void ServiceTimer_Tick(object state) { OdbcConnection oCon = new OdbcConnection(); oCon.ConnectionString = ConnectionStrings; OdbcDataAdapter dp = new OdbcDataAdapter("SELECT * FROM table", oCon); dsProva.Tables.Clear(); dp.Fill(dsProva,"table"); dataGridViewMessaggi.DataSource = dsProva.Tables["table"]; dataGridViewMessaggi.Refresh(); } But every Timer Tick i lost the selection in DatagridView and Current Row .... Is There a better solution ?

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  • sizer.replace() paints "over" old sizercontent

    - by elbenfreund
    hi. I am rather new to wx/python so please excuse if this is stupid or ill described. I am substituting a nested sizer with a new one as shown in the snippet below. after some tinkering everything seems to work out but the re-drawing of the parent-sizer. the content of the old nested sizer remains and gets "painted" over with the new sizer content despite my sizer.Layout() system setup: - python 2.5.5.2 and 2.6.4 - wxpython 2.8 -- coding: utf8 -- import wx class Frame(wx.Frame): def init(self): wx.Frame.init(self, None, wx.ID_ANY, title='test') class Test(wx.App): def OnInit(self): frame = Frame() self.panel = wx.Panel(frame) self.panel.SetBackgroundColour('red') self.sizer = wx.BoxSizer(wx.VERTICAL) button = wx.Button(self.panel, wx.ID_ANY, 'TEST') self.hsizer = wx.BoxSizer(wx.HORIZONTAL) self.hsizer.Add(wx.StaticText(self.panel, wx.ID_ANY, 'nacknack')) self.sizer.Add(button) self.Bind(wx.EVT_BUTTON, self.on_test_button, button) self.text = wx.StaticText(self.panel, wx.ID_ANY, 'FOOO') self.sizer.Add(self.text) self.sizer.Add(self.hsizer) self.panel.SetSizer(self.sizer) frame.Show() return True def on_test_button(self, evt): tmpsizer = wx.BoxSizer(wx.VERTICAL) tmpsizer.Add(self.makesizer()) tmpitem = tmpsizer.GetChildren()[0] self.sizer.Replace(2, tmpitem) self.sizer.Layout() def makesizer(self): testsizer = wx.BoxSizer(wx.HORIZONTAL) testsizer.Add(wx.StaticText(self.panel, wx.ID_ANY, 'testsizer')) return testsizer if __name__ == '__main__': app = Test() app.MainLoop()

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  • Should I use a regular server instead of AWS?

    - by Jon Ramvi
    Reading about and using the Amazon Web Services, I'm not really able to grasp how to use it correctly. Sorry about the long question: I have a EC2 instance which mostly does the work of a web server (apache for file sharing and Tomcat with Play Framework for the web app). As it's a web server, the instance is running 24/7. It just came to my attention that the data on the EC2 instance is non persistent. This means I lose my database and files if it's stopped. But I guess it also means my server settings and installed applications are lost as they are just files in the same way as the other data. This means that I will either have to rewrite the whole app to use amazon CloudDB or write some code which stores the db on S3 and make my own AMI with the correct applications installed and configured. Or can this be quick-fixed by using EBS somehow? My question is 1. is my understanding of aws is correct? and 2. is it's worth it? It could be a possibility to just set up a regular dedicated server where everything is persistent, as you would expect. Would love to have the scaleability of aws though..

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  • Stack Overflow problem transforming with a custom xslt

    - by Flynn1179
    I've got a system that allows the user the option of providing their own XSLT to apply to some data that's been retrieved, as a means of specifying how that data should be presented. However, if the user includes code in the XSLT equivalent to: <xsl:template match="/"> <xsl:element name="data"> <xsl:apply-templates select="." /> </xsl:element> </xsl:template> this causes .NET to infinitely recurse trying to process it, and produces a stack overflow error. I need to be able to trap this before it crashes the app, as the data that's been retrieved is occasionally quite time-consuming to obtain, and the data is lost when this happens. Is there any way of doing this? I know it's theoretically possible to identify any occurrences of xsl:apply-templates with "." in the select attribute, but this isn't the only way an infinite recursion could happen, I need a way of generically trapping it.

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  • How to Resolve a Transformation Service with BRE that occurs after an Orchestration in an Itinerary?

    - by Maxime Labelle
    In trying to implement simple integration patterns with Biztalk ESB Toolkit 2.0, I'm facing a problem trying to resolve a Transformation Itinerary Service that occurs after an Orchestration. I'm using the BRE Resolver to execute rules that need to inspect the Context Message Type property to determine the appropriate map to use. However, once the message reaches the step in the Itinerary associated with the Transformation Service, the map fails to execute. From careful investigation, it appears that the message type is not supplied to the "Resolution" object that is used internally by the BRE resolver. Indeed, since the message leaving the preceding Orchestration is typed System.Xml.XmlDocument, the type of the message is "demoted" from the context. By tracking rules engine execution, I can observe that the type of the message is indeed lost when reaching the BRE resolver. The type of the message is empty, whereas the strongly-typed of the document is Microsoft.XLANGs.BaseTypes.Any. The Orchestration service that I use is taken straight from the samples that ship with ESB Toolkit 2.0. Is there a way to perform Context-Based BRE resolution after an Orchestration in an Itinerary?

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  • BCrypt says long, similar passwords are equivalent - problem with me, the gem, or the field of crypt

    - by PreciousBodilyFluids
    I've been experimenting with BCrypt, and found the following. If it matters, I'm running ruby 1.9.2dev (2010-04-30 trunk 27557) [i686-linux] require 'bcrypt' # bcrypt-ruby gem, version 2.1.2 @long_string_1 = 'f287ed6548e91475d06688b481ae8612fa060b2d402fdde8f79b7d0181d6a27d8feede46b833ecd9633b10824259ebac13b077efb7c24563fce0000670834215' @long_string_2 = 'f6ebeea9b99bcae4340670360674482773a12fd5ef5e94c7db0a42800813d2587063b70660294736fded10217d80ce7d3b27c568a1237e2ca1fecbf40be5eab8' def salted(string) @long_string_1 + string + @long_string_2 end encrypted_password = BCrypt::Password.create(salted('password'), :cost => 10) puts encrypted_password #=> $2a$10$kNMF/ku6VEAfLFEZKJ.ZC.zcMYUzvOQ6Dzi6ZX1UIVPUh5zr53yEu password = BCrypt::Password.new(encrypted_password) puts password.is_password?(salted('password')) #=> true puts password.is_password?(salted('passward')) #=> true puts password.is_password?(salted('75747373')) #=> true puts password.is_password?(salted('passwor')) #=> false At first I thought that once the passwords got to a certain length, the dissimilarities would just be lost in all the hashing, and only if they were very dissimilar (i.e. a different length) would they be recognized as different. That didn't seem very plausible to me, from what I know of hash functions, but I didn't see a better explanation. Then, I tried shortening each of the long_strings to see where BCrypt would start being able to tell them apart, and I found that if I shortened each of the long strings to 100 characters or so, the final attempt ('passwor') would start returning true as well. So now I don't know what to think. What's the explanation for this?

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  • Why do WCF clients depend on the app.config file?

    - by routeNpingme
    Like a lot of things, I'm sure there's a good reason for this, so please help me understand... Why, by default, do WCF services store settings in app.config? This has been so frustrating trying to work with multiple Silverlight class libraries. These class libraries are supposed to be completely independent from each other, and this dependency on the app.config seems to cause the following headaches: Single Responsibility Principle - I should be able to add a reference to a class library and go. If that class library uses a service reference, this idea is shot before I even start coding against it. Muddy Configuration - To get other libraries to work, I have to copy and paste the service configurations into the "main" application configs. If an endpoint changes in any way, I can't just worry about a new version of that class DLL - I have to worry about anything that uses it, too. Complex Alternatives - Programmatically creating the endpoint isn't pretty. Period. There has to be a better way. Why doesn't WCF at least separate the service configurations into a ServiceName.config or something that gets copied to an output directory. What am I missing? How do you deal with this?

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  • Problems with display of UTF-8 encoded content from a DB

    - by LookUp Webmaster
    Dear members of the Stackoverflow community, We are developing a web application using the Zend Framework, and we are facing some encoding issues that we hope you might help us solve. The situation goes something like this: There are certain tables on a MySQL database that need to be displayed as html. Because the site is designed using the Spanish language, the database contains some characters like "á" or "ñ". Our internal policy is to set all the encodings as UTF-8, including all the databases and the tables. The problem is, that when we retrieve the content from the DB, some characters are displayed as question marks. We are out of ideas. These are all the things that we have already tried and double-checked: 1. The SQL file from which we load all the data is properly UTF-8 encoded. 2. The SQL is loaded through phpmyadmin (which is configured as UTF-8), and the resulting tables are displayed properly. 3. The netbeans environment used for coding is also set as UTF-8. The weird thing is that all the content that is hard-coded either as php or html is displayed properly. Only the values that are extracted from the database have issues. Any ideas? Thank you very much.

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  • wpf: capturing mouse does not work

    - by amethyste
    hello I am developing an kind of outlook calendar application where I need to make the appointment resizable from mouse. My first try with a thumb did not work properly so I tried another way. What I did is that: 1) on the botton of the appointmennt panel I added a rectangle to figure out the resize zone (the thumb). The appointment panel is put on a grid panel. 2) I intercept down event on the rectangle and send event to this code: private Point startPoint; private void OnResizeElementMouseDown(object sender, MouseButtonEventArgs e) { e.Handled = true; this.MouseMove += new MouseEventHandler(ResizeEndElement_MouseMove); this.MouseLeftButtonUp += new MouseButtonEventHandler(OnResizeElementMouseUp); // some code to perform new height computation Mouse.Capture(this); } where this is the appointment panel that own the thumb. Decreasing height works well. But increasing is more difficult. If I move the mouse very very slowly it's OK, if I speed it up a little bit it tends to leave out the appointment panel and then all MouseMove event are lost. I thought Mouse.Capture() was propose to solve this kind of problem, but in fact not. Does anybody know what is wrong in my code?

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  • Incorrect logic flow? function that gets coordinates for a sudoku game

    - by igor
    This function of mine keeps on failing an autograder, I am trying to figure out if there is a problem with its logic flow? Any thoughts? Basically, if the row is wrong, "invalid row" should be printed, and clearInput(); called, and return false. When y is wrong, "invalid column" printed, and clearInput(); called and return false. When both are wrong, only "invalid row" is to be printed (and still clearInput and return false. Obviously when row and y are correct, print no error and return true. My function gets through most of the test cases, but fails towards the end, I'm a little lost as to why. bool getCoords(int & x, int & y) { char row; bool noError=true; cin>>row>>y; row=toupper(row); if(row>='A' && row<='I' && isalpha(row) && y>=1 && y<=9) { x=row-'A'; y=y-1; return true; } else if(!(row>='A' && row<='I')) { cout<<"Invalid row"<<endl; noError=false; clearInput(); return false; } else { if(noError) { cout<<"Invalid column"<<endl; } clearInput(); return false; } }

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  • Application design question, best approach?

    - by Jamie Keeling
    Hello, I am in the process of designing an application that will allow you to find pictures (screen shots) made from certain programs. I will provide the locations of a few of the program in the application itself to get the user started. I was wondering how I should go about adding new locations as the time goes on, my first thought was simply hard coding it into the application but this will mean the user has to reinstall it to make the changes take affect. My second idea was to use an XML file to contain all the locations as well as other data, such as the name of the application. This also means the user can add their own locations if they wish as well as sharing them over the internet. The second option seemed the best approach but then I had to think how would it be managed on the users computer. Ideally I'd like just a single .exe without the reliance on any external files such as the XML but this would bring me back to point one. Would it be best to simply use the ClickOnce deployment to create an entry in the start menu and create a folder containing the .exe and the file names? Thanks for the feedback, I don't want to start implementing the application until the design is nailed.

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  • Performance difference in for loop condition?

    - by CSharperWithJava
    Hello all, I have a simple question that I am posing mostly for my curiousity. What are the differences between these two lines of code? (in C++) for(int i = 0; i < N, N > 0; i++) for(int i = 0; i < N && N > 0; i++) The selection of the conditions is completely arbitrary, I'm just interested in the differences between , and &&. I'm not a beginner to coding by any means, but I've never bothered with the comma operator. Are there performance/behavior differences or is it purely aesthetic? One last note, I know there are bigger performance fish to fry than a conditional operator, but I'm just curious. Indulge me. Edit Thanks for your answers. It turns out the code that prompted this question had misused the comma operator in the way I've described. I wondered what the difference was and why it wasn't a && operator, but it was just written incorrectly. I didn't think anything was wrong with it because it worked just fine. Thanks for straightening me out.

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  • gpg error - connection already closed?

    - by OopsForgotMyOtherUserName
    omg... hope someone can help me because I am so lost as to what to try next.... I don't know what is causing the error to happen, and I don't see how to figure it out... Keep going between the pgloader.conf examples and what I have, and I don't understand why I keep getting the 'connection already closed' error? The first few lines of my fr.conf is at the very end... I'd really appreciate / love some guidance here... Been trying to get this thing going all morning, and am even getting stuck just on this part... Running this command at the command line: /usr/bin/pgloader -c /var/mybin/pgconfs/fr.conf Yields this in the pgloader.log (with the process just hanging) more /tmp/pgloader.log 27-03-2010 12:22:53 pgloader INFO Logger initialized 27-03-2010 12:22:53 pgloader INFO Reformat path is ['/usr/share/python-support/pgloader/reformat'] 27-03-2010 12:22:53 pgloader INFO Will consider following sections: 27-03-2010 12:22:53 pgloader INFO fixed 27-03-2010 12:22:54 fixed INFO fixed processing 27-03-2010 12:22:54 pgloader INFO All threads are started, wait for them to terminate 27-03-2010 12:22:57 fixed ERROR connection already closed 27-03-2010 12:22:57 fixed INFO closing current database connection [pgsql] host = localhost port = 5432 base = frdb user = username pass = password [fixed] table = fr format = fixed filename = /var/www/fr.txt ...

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  • Core Data: migrating entities with self-referential properties

    - by Dan
    My Core Data model contains an entity, Shape, that has two self-referential relationships, which means four properties. One pair is a one-to-many relationship (Shape.containedBy <- Shape.contains) and the another is a many-to-many relationship (Shape.nextShapes <<- Shape.previousShapes). It all works perfectly in the application, so I don't think self-referencing relationships is a problem in general. However, when it comes to migrating the model to a new version, then Xcode fails to compile the automatically generated mapping model, with this error message: 2009-10-30 17:10:09.387 mapc[18619:607] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Unable to parse the format string "FUNCTION($manager ,'destinationInstancesForSourceRelationshipNamed:sourceInstances:' , 'contains' , $source.contains) == 1"' *** Call stack at first throw: ( 0 CoreFoundation 0x00007fff80d735a4 __exceptionPreprocess + 180 1 libobjc.A.dylib 0x00007fff83f0a313 objc_exception_throw + 45 2 Foundation 0x00007fff819bc8d4 _qfqp2_performParsing + 8412 3 Foundation 0x00007fff819ba79d +[NSPredicate predicateWithFormat:arguments:] + 59 4 Foundation 0x00007fff81a482ef +[NSExpression expressionWithFormat:arguments:] + 68 5 Foundation 0x00007fff81a48843 +[NSExpression expressionWithFormat:] + 155 6 XDBase 0x0000000100038e94 -[XDDevRelationshipMapping valueExpressionAsString] + 260 7 XDBase 0x000000010003ae5c -[XDMappingCompilerSupport generateCompileResultForMappingModel:] + 2828 8 XDBase 0x000000010003b135 -[XDMappingCompilerSupport compileSourcePath:options:] + 309 9 mapc 0x0000000100001a1c 0x0 + 4294973980 10 mapc 0x0000000100001794 0x0 + 4294973332 ) terminate called after throwing an instance of 'NSException' Command /Developer/usr/bin/mapc failed with exit code 6 The 'contains' is the name of one of the self-referential properties. Anyway, the really big problem is that I can't even look at this Mapping Property as Xcode crashes as soon as I select the entity mapping when viewing the mapping model. So I'm a bit lost really where to go from here. I really can't remove the self-referential properties, so I'm thinking I've got manually create a mapping model that compiles? Any ideas? Cheers

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  • Where can a self-teacher learn general good programming habits and conventions?

    - by lucid
    A few mistakes and general childishness in early adulthood have left me in a situation where I work a menial job, with no possibility (in the near future) of attending school. I aspire to one day work in the programming field (gaming specifically), after proving myself on the indie end of things. I've gotten very confident in C++, java, and python, and I find I'm able to solve any problem I want either from previous experience, or from scouring the web for help. The solutions work, and with each attempt they become more readable, maintainable, and extensible. But this is because I'm learning from mistakes and bad programming and design habits I feel I might have avoided with actual schooling. General tips like: "if it's hard to read or getting long, or you're writing it twice, it should be in one or more functions." or "design all your classes before you start coding, so you don't have to rewrite classes later when you discover an unforeseen dependency" Is there a good book or website for learning general good programming practices and design habits? Also, naming and format conventions. I realize sometimes development houses have their own conventions, but things like "Classes in python usually have the first letter of each word capitalized". I'd like to be able to show some source code to a potential employer, and be prepared when for what's expected on a team. Is there some central database of naming and formatting conventions somewhere? Also, feel free to give any thoughts on whether or not the self-teach, garner some indie sales, use them as your resume' route is realistic

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  • Update Datatable and DatagridView with database Changes by Timer

    - by aleroot
    Scenario : i have a database table that is being updated frequently by some services. I have a c# Winforms Application that load this table in a datagridview by binding a datatable as Datasource, then i whant to add a Timer that every 10 seconds update a the content of a datatable with the last changes in the database table ... I don't need to update a database with the datatable changes, but i need to update datatable with the last changes in the database table, that is the inverse of the usually.... Is there a way to do that ? What is the best way ? i've tried with this code : private void ServiceTimer_Tick(object state) { OdbcConnection oCon = new OdbcConnection(); oCon.ConnectionString = ConnectionStrings; OdbcDataAdapter dp = new OdbcDataAdapter("SELECT * FROM table", oCon); dsProva.Tables.Clear(); dp.Fill(dsProva,"table"); dataGridViewMessaggi.DataSource = dsProva.Tables["table"]; dataGridViewMessaggi.Refresh(); } But every Timer Tick i lost the selection in DatagridView and Current Row .... Is There a better solution ?

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  • Why Does Private Access Remain Non-Private in .NET Within a Class?

    - by AMissico
    While cleaning some code today written by someone else, I changed the access modifier from Public to Private on a class variable/member/field. I expected a long list of compiler errors that I use to "refactor/rework/review" the code that used this variable. Imagine my surprise when I didn't get any errors. After reviewing, it turns out that another instance of the Class can access the private members of another instance declared within the Class. Totally unexcepted. Is this normal? I been coding in .NET since the beginning and never ran into this issue, nor read about it. I may have stumbled onto it before, but only "vaguely noticed" and move on. Can anyone explain this behavoir to me? Am I doing something wrong? I found this behavior in both C# and VB.NET. The code seems to take advantage of the ability to access private variables. Sincerely, Totally Confused Class Foo Private _int As Integer Private _foo As Foo Private _jack As Jack Private _fred As Fred Public Sub SetPrivate() _foo = New Foo _foo._int = 3 'TOTALLY UNEXPECTED _jack = New Jack '_jack._int = 3 'expected compile error because Foo doesn't know Jack _fred = New Fred '_fred._int = 3 'expected compile error because Fred hides from Foo End Sub Private Class Fred Private _int As Integer End Class End Class Class Jack Private _int As Integer End Class

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  • How do you make life easier for yourself when developing a really large database

    - by Hannes de Jager
    I am busy developing 2 web based systems with MySql databases and the amount of tables/views/stored routines is really becoming a lot and it is more and more challenging to handle the complexity. Now in programming languages we have namespacing e.g. Java packages, C++ namespaces to partition the software, grouping it together to make things more understandable. Databases on the other hand have more of a flat structure (MySql at least) e.g. tables and stored procedures are on the same level. So one have to be more creative, creating naming conventions, perhaps use more than one database or using tools to visualize things. What methods do you use to ease the pain? To be effective while developing your databases? To not get lost in a sea of tables and fields and stored procs? Feel free to mention tools you use also, but try to restrict it to open source and preferably Linux solutions if thats OK. b.t.w How many tables would a database have to be considered large in terms of design?

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