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  • java - unwanted object overwriting

    - by gosling
    Hello everyone! I'm trying to make a program that solves the logic wheels puzzle. I construct the root node and I try to produce the different child-nodes that are produced by making different moves of the wheels. The problem is that while I try to produce the children, the root node is overwrited,and everything is messed-up and I really don't know why. Here you can find the puzzle logic wheels. I represent the wheels as 3x3 arrays. Here is the code that implements the moves: public Node turn_right(Node aNode, int which_wheel) { Node newNode = new Node(aNode.getYellow_wheel(),aNode.getBlue_wheel(),aNode.getGreen_wheel()); int[][] yellow = new int[3][3]; int[][] blue = new int[3][3]; int[][] green = new int[3][3]; if(which_wheel==0) //turn yellow wheel of this node to right { yellow[1][0] = newNode.getYellow_wheel()[0][0]; yellow[2][0] = newNode.getYellow_wheel()[1][0]; yellow[2][1] = newNode.getYellow_wheel()[2][0]; yellow[2][2] = newNode.getYellow_wheel()[2][1]; yellow[1][2] = newNode.getYellow_wheel()[2][2]; yellow[0][2] = newNode.getYellow_wheel()[1][2]; yellow[0][1] = newNode.getYellow_wheel()[0][2]; yellow[0][0] = newNode.getYellow_wheel()[0][1]; blue = newNode.getBlue_wheel(); blue[1][0] = newNode.getYellow_wheel()[1][2]; blue[2][0] = newNode.getYellow_wheel()[2][2]; green = newNode.getGreen_wheel(); } else if(which_wheel == 1)// turn blue wheel of this node to right { blue[1][0] = newNode.getBlue_wheel()[0][0]; blue[2][0] = newNode.getBlue_wheel()[1][0]; blue[2][1] = newNode.getBlue_wheel()[2][0]; blue[2][2] = newNode.getBlue_wheel()[2][1]; blue[1][2] = newNode.getBlue_wheel()[2][2]; blue[0][2] = newNode.getBlue_wheel()[1][2]; blue[0][1] = newNode.getBlue_wheel()[0][2]; blue[0][0] = newNode.getBlue_wheel()[0][1]; yellow = newNode.getYellow_wheel(); yellow[0][2] = newNode.getBlue_wheel()[0][0]; yellow[1][2] = newNode.getBlue_wheel()[1][0]; green = newNode.getGreen_wheel(); green[1][0] = newNode.getBlue_wheel()[1][2]; green[2][0] = newNode.getBlue_wheel()[2][2]; } else if (which_wheel == 2)//turn green wheel of this node to right { green[0][0] = newNode.getGreen_wheel()[0][1]; green[0][1] = newNode.getGreen_wheel()[0][2]; green[0][2] = newNode.getGreen_wheel()[1][2]; green[1][2] = newNode.getGreen_wheel()[2][2]; green[2][2] = newNode.getGreen_wheel()[2][1]; green[2][1] = newNode.getGreen_wheel()[2][0]; green[2][0] = newNode.getGreen_wheel()[1][0]; green[1][0] = newNode.getGreen_wheel()[0][0]; yellow = newNode.getYellow_wheel(); blue = newNode.getBlue_wheel(); blue[0][2] = newNode.getGreen_wheel()[0][0]; blue[1][2] = newNode.getGreen_wheel()[1][0]; } newNode= new Node(yellow,blue,green); return newNode; } There is another function, like this one that does the oposite:it turns the wheels to left. My problem is that I do not want object's aNode tables to be overwritten. Thank you very much.

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  • function fetch() on a non-object problem

    - by shin
    I have this url, http://webworks.net/ww.incs/forgotten-password-verification.php?verification_code=974bf747124c69f12ae3b36afcaccc68&[email protected]&redirect=/ww.admin/index.php And this gives the following error. Fatal error: Call to a member function fetch() on a non-object in /var/www/webworks/ww.incs/basics.php on line 23 Call Stack: 0.0005 338372 1. {main}() /var/www/webworks/ww.incs/forgotten-password-verification.php: 0 0.0020 363796 2. dbRow() /var/www/webworks/ww.incs/forgotten-password-verification.php:18 The forgotten-password-verification.php require 'login-libs.php'; login_check_is_email_provided(); // check that a verification code was provided if( !isset($_REQUEST['verification_code']) || $_REQUEST['verification_code']=='' ){ login_redirect($url,'novalidation'); } // check that the email/verification code combination matches a row in the user table // $password=md5($_REQUEST['email'].'|'.$_REQUEST['password']); $r=dbRow('select * from user_accounts where email="'.addslashes($_REQUEST['email']).'" and verification_code="'.$_REQUEST['verification_code'].'" and active' ); if($r==false){ login_redirect($url,'validationfailed'); } // success! set the session variable, then redirect $_SESSION['userdata']=$r; $groups=json_decode($r['groups']); $_SESSION['userdata']['groups']=array(); foreach($groups as $g)$_SESSION['userdata']['groups'][$g]=true; if($r['extras']=='')$r['extras']='[]'; $_SESSION['userdata']['extras']=json_decode($r['extras']); login_redirect($url); And login-libs, require 'basics.php'; $url='/'; $err=0; function login_redirect($url,$msg='success'){ if($msg)$url.='?login_msg='.$msg; header('Location: '.$url); echo '<a href="'.htmlspecialchars($url).'">redirect</a>'; exit; } // set up the redirect if(isset($_REQUEST['redirect'])){ $url=preg_replace('/[\?\&].*/','',$_REQUEST['redirect']); if($url=='')$url='/'; } // check that the email address is provided and valid function login_check_is_email_provided(){ if( !isset($_REQUEST['email']) || $_REQUEST['email']=='' || !filter_var($_REQUEST['email'], FILTER_VALIDATE_EMAIL) ){ login_redirect($GLOBALS['url'],'noemail'); } } // check that the captcha is provided function login_check_is_captcha_provided(){ if( !isset($_REQUEST["recaptcha_challenge_field"]) || $_REQUEST["recaptcha_challenge_field"]=='' || !isset($_REQUEST["recaptcha_response_field"]) || $_REQUEST["recaptcha_response_field"]=='' ){ login_redirect($GLOBALS['url'],'nocaptcha'); } } // check that the captcha is valid function login_check_is_captcha_valid(){ require 'recaptcha.php'; $resp=recaptcha_check_answer( RECAPTCHA_PRIVATE, $_SERVER["REMOTE_ADDR"], $_REQUEST["recaptcha_challenge_field"], $_REQUEST["recaptcha_response_field"] ); if(!$resp->is_valid){ login_redirect($GLOBALS['url'],'invalidcaptcha'); } } basics.php is, session_start(); function __autoload($name) { require $name . '.php'; } function dbInit(){ if(isset($GLOBALS['db']))return $GLOBALS['db']; global $DBVARS; $db=new PDO('mysql:host='.$DBVARS['hostname'].';dbname='.$DBVARS['db_name'],$DBVARS['username'],$DBVARS['password']); $db->query('SET NAMES utf8'); $db->num_queries=0; $GLOBALS['db']=$db; return $db; } function dbQuery($query){ $db=dbInit(); $q=$db->query($query); $db->num_queries++; return $q; } function dbRow($query) { $q = dbQuery($query); return $q->fetch(PDO::FETCH_ASSOC); } define('SCRIPTBASE', $_SERVER['DOCUMENT_ROOT'] . '/'); require SCRIPTBASE . '.private/config.php'; if(!defined('CONFIG_FILE'))define('CONFIG_FILE',SCRIPTBASE.'.private/config.php'); set_include_path(SCRIPTBASE.'ww.php_classes'.PATH_SEPARATOR.get_include_path()); I am not sure how to solve the problem. Any help will be appreciated. Thanks in advance. UPDATE: My db CREATE TABLE IF NOT EXISTS `user_accounts` ( `id` int(11) unsigned NOT NULL AUTO_INCREMENT, `email` text, `password` char(32) DEFAULT NULL, `active` tinyint(4) DEFAULT '0', `groups` text, `activation_key` varchar(32) DEFAULT NULL, `extras` text, PRIMARY KEY (`id`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 AUTO_INCREMENT=10 ; INSERT INTO `user_accounts` (`id`, `email`, `password`, `active`, `groups`, `activation_key`, `extras`) VALUES (2, '[email protected]', '6d24dde9d56b9eab99a303a713df2891', 1, '["_superadministrators"]', '5d50e39420127d0bab44a56612f2d89b', NULL), (3, '[email protected]', 'e83052ab33df32b94da18f6ff2353e94', 1, '[]', NULL, NULL), (9, '[email protected]', '9ca3eee3c43384a575eb746eeae0f279', 1, '["_superadministrators"]', '974bf747124c69f12ae3b36afcaccc68', NULL);

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  • Silverlight: Binding a custom control to an arbitrary object

    - by Ryan Bates
    I am planning on writing a hierarchical organizational control, similar to an org chart. Several org chart implementations are out there, but not quite fit what I have in mind. Binding fields in a DataTemplate to a custom object does not seem to work. I started with a generic, custom control, i.e. public class NodeBodyBlock : ContentControl { public NodeBodyBlock() { this.DefaultStyleKey = typeof(NodeBodyBlock); } } It has a simple style in generic.xaml: <Style TargetType="org:NodeBodyBlock"> <Setter Property="Width" Value="200" /> <Setter Property="Height" Value="100" /> <Setter Property="Background" Value="Lavender" /> <Setter Property="FontSize" Value="11" /> <Setter Property="Template"> <Setter.Value> <ControlTemplate TargetType="org:NodeBodyBlock"> <Border Width="{TemplateBinding Width}" Height="{TemplateBinding Height}" Background="{TemplateBinding Background}" CornerRadius="4" BorderBrush="Black" BorderThickness="1" > <Grid> <VisualStateManager/> ... clipped for brevity </VisualStateManager.VisualStateGroups> <ContentPresenter Content="{TemplateBinding Content}" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" /> </Grid> </Border> </ControlTemplate> </Setter.Value> </Setter> </Style> My plan now is to be able to use this common definition as a base definition of sorts, with customized version of it used to display different types of content. A simple example would be to use this on a user control with the following style: <Style TargetType="org:NodeBodyBlock" x:Key="TOCNode2"> <Setter Property="ContentTemplate"> <Setter.Value> <DataTemplate> <StackPanel> <TextBlock Text="{Binding Path=NodeTitle}"/> </StackPanel> </DataTemplate> </Setter.Value> </Setter> </Style> and an instance defined as <org:NodeBodyBlock Style="{StaticResource TOCNode2}" x:Name="stTest" DataContext="{StaticResource DummyData}" /> The DummyData is defined as <toc:Node NodeNumber="mynum" NodeStatus="A" NodeTitle="INLine Node Title!" x:Key="DummyData"/> With a simple C# class behind it, where each of the fields is a public property. When running the app, the Dummy Data values simply do not show up in the GUI. A trivial test such as <TextBlock Text="{Binding NodeTitle}" DataContext="{StaticResource DummyData}"/> works just fine. Any ideas around where I am missing the plot?

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  • Associating an Object with other Objects and Properties of those Objects

    - by alzoid
    I am looking for some help with designing some functionality in my application. I already have something similar designed but this problem is a little different. Background: In my application we have different Modules. Data in each module can be associated to other modules. Each Module is represented by an Object in our application. Module 1 can be associated with Module 2 and Module 3. Currently I use a factory to provide the proper DAO for getting and saving this data. It looks something like this: class Module1Factory { public static Module1BridgeDAO createModule1BridgeDAO(int moduleid) { switch (moduleId) { case Module.Module2Id: return new Module1_Module2DAO(); case Module.Module3Id: return new Module1_Module3DAO(); default: return null; } } } Module1_Module2 and Module1_Module3 implement the same BridgeModule interface. In the database I have a Table for every module (Module1, Module2, Module3). I also have a bridge table for each module (they are many to many) Module1_Module2, Module1_Module3 etc. The DAO basically handles all code needed to manage the association and retrieve its own instance data for the calling module. Now when we add new modules that associate with Module1 we simply implement the ModuleBridge interface and provide the common functionality. New Development We are adding a new module that will have the ability to be associated with other Modules as well as specific properties of that module. The module is basically providing the user the ability to add their custom forms to our other modules. That way they can collect additional information along with what we provide. I want to start associating my Form module with other modules and their properties. Ie if Module1 has a property Category, I want to associate an instance From data with that property. There are many Forms. If a users creates an instance of Module2, they may always want to also have certain form(s) attached to that Module2 instance. If they create an instance of Module2 and select Category 1, then I may want additional Form(s) created. I prototyped something like this: Form FormLayout (contains the labels and gui controls) FormModule (associates a form with all instances of a module) Form Instance (create an instance of a form to be filled out) As I thought about it I was thinking about making a new FormModule table/class/dao for each Module and Property that I add. So I might have: FormModule1 FormModule1Property1 FormModule1Property2 FormModule1Property3 FormModule1Property4 FormModule2 FormModule3 FormModule3Property1 Then as I did previously, I would use a factory to get the proper DAO for dealing with all of these. I would hand it an array of ids representing different modules and properties and it would return all of the DAOs that I need to call getForms(). Which in turn would return all of the forms for that particular bridge. Some points This will be for a new module so I dont need to expand on the factory code I provided. I just wanted to show an example of what I have done in the past. The new module can be associated with: Other Modules (ie globally for any instance of that module data), Other module properties (ie only if the Module instance has a certian value in one of its properties) I want to make it easy for developers to add associations with other modules and properties easily Can any one suggest any design patterns or strategy's for achieving this? If anything is unclear please let me know. Thank you, Al

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  • When using method chaining, do I reuse the object or create one?

    - by MainMa
    When using method chaining like: var car = new Car().OfBrand(Brand.Ford).OfModel(12345).PaintedIn(Color.Silver).Create(); there may be two approaches: Reuse the same object, like this: public Car PaintedIn(Color color) { this.Color = color; return this; } Create a new object of type Car at every step, like this: public Car PaintedIn(Color color) { var car = new Car(this); // Clone the current object. car.Color = color; // Assign the values to the clone, not the original object. return car; } Is the first one wrong or it's rather a personal choice of the developer? I believe that he first approach may quickly cause the intuitive/misleading code. Example: // Create a car with neither color, nor model. var mercedes = new Car().OfBrand(Brand.MercedesBenz).PaintedIn(NeutralColor); // Create several cars based on the neutral car. var yellowCar = mercedes.PaintedIn(Color.Yellow).Create(); var specificModel = mercedes.OfModel(99).Create(); // Would `specificModel` car be yellow or of neutral color? How would you guess that if // `yellowCar` were in a separate method called somewhere else in code? Any thoughts?

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  • How to define type-specific scripts when using a 'type object' programming pattern?

    - by Erik
    I am in the process of creating a game engine written in C++, using the C/C++ SQLite interface to achieve a 'type object' pattern. The process is largely similar to what is outlined here (Thank you Bob Nystrom for the great resource!). I have a generally defined Entity class that when a new object is created, data is taken from a SQLite database and then is pushed back into a pointer vector, which is then iterated through, calling update() for each object. All the ints, floats, strings are loaded in fine, but the script() member of Entity is proving an issue. It's not much fun having a bunch of stationary objects laying around my gameworld. The only solutions I've come up with so far are: Create a monolithic EntityScript class with member functions encompassing all game AI and then calling the corresponding script when iterating through the Entity vector. (Not ideal) Create bindings between C++ and a scripting language. This would seem to get the job done, but it feels like implementing this (given the potential memory overhead) and learning a new language is overkill for a small team (2-3 people) that know the entirety of the existing game engine. Can you suggest any possible alternatives? My ideal situation would be that to add content to the game, one would simply add a script file to the appropriate directory and append the SQLite database with all the object data. All that is required is to have a variety of integers and floats passed between both the engine and the script file.

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  • Can't get running JPA2 with Hibernate and Maven

    - by erlord
    Have been trying the whole day long and googled the ** out of the web ... in vain. You are my last hope: Here's my code: The Entity: package sas.test.model; import javax.persistence.Entity; import javax.persistence.Id; @Entity public class Employee { @Id private int id; private String name; private long salary; public Employee() {} public Employee(int id) { this.id = id; } public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public long getSalary() { return salary; } public void setSalary (long salary) { this.salary = salary; } } The service class: package sas.test.dao; import sas.test.model.Employee; import javax.persistence.*; import java.util.List; public class EmployeeService { protected EntityManager em; public EmployeeService(EntityManager em) { this.em = em; } public Employee createEmployee(int id, String name, long salary) { Employee emp = new Employee(id); emp.setName(name); emp.setSalary(salary); em.persist(emp); return emp; } public void removeEmployee(int id) { Employee emp = findEmployee(id); if (emp != null) { em.remove(emp); } } public Employee raiseEmployeeSalary(int id, long raise) { Employee emp = em.find(Employee.class, id); if (emp != null) { emp.setSalary(emp.getSalary() + raise); } return emp; } public Employee findEmployee(int id) { return em.find(Employee.class, id); } } And the main class: package sas.test.main; import javax.persistence.*; import java.util.List; import sas.test.model.Employee; import sas.test.dao.EmployeeService; public class ExecuteMe { public static void main(String[] args) { EntityManagerFactory emf = Persistence.createEntityManagerFactory("EmployeeService"); EntityManager em = emf.createEntityManager(); EmployeeService service = new EmployeeService(em); // create and persist an employee em.getTransaction().begin(); Employee emp = service.createEmployee(158, "John Doe", 45000); em.getTransaction().commit(); System.out.println("Persisted " + emp); // find a specific employee emp = service.findEmployee(158); System.out.println("Found " + emp); // find all employees // List<Employee> emps = service.findAllEmployees(); // for (Employee e : emps) // System.out.println("Found employee: " + e); // update the employee em.getTransaction().begin(); emp = service.raiseEmployeeSalary(158, 1000); em.getTransaction().commit(); System.out.println("Updated " + emp); // remove an employee em.getTransaction().begin(); service.removeEmployee(158); em.getTransaction().commit(); System.out.println("Removed Employee 158"); // close the EM and EMF when done em.close(); emf.close(); } } Finally my confs. pom.xml: <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>Test_JPA_CRUD</groupId> <artifactId>Test_JPA_CRUD</artifactId> <packaging>jar</packaging> <version>1.0</version> <name>Test_JPA_CRUD</name> <url>http://maven.apache.org</url> <repositories> <repository> <id>maven2-repository.dev.java.net</id> <name>Java.net Repository for Maven</name> <url>http://download.java.net/maven/2/ </url> <layout>default</layout> </repository> <repository> <id>maven.org</id> <name>maven.org Repository</name> <url>http://repo1.maven.org/maven2</url> <releases> <enabled>true</enabled> </releases> <snapshots> <enabled>true</enabled> </snapshots> </repository> </repositories> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.8.1</version> <scope>test</scope> </dependency> <!-- <dependency> <groupId>javax</groupId> <artifactId>javaee-api</artifactId> <version>6.0</version> </dependency> --> <!-- <dependency> <groupId>javax.persistence</groupId> <artifactId>persistence-api</artifactId> <version>1.0</version> </dependency> --> <!-- JPA2 provider --> <dependency> <groupId>org.hibernate</groupId> <artifactId>hibernate-entitymanager</artifactId> <version>3.4.0.GA</version> </dependency> <!-- JDBC driver --> <dependency> <groupId>org.apache.derby</groupId> <artifactId>derby</artifactId> <version>10.5.3.0_1</version> </dependency> <dependency> <groupId>org.hibernate</groupId> <artifactId>hibernate-core</artifactId> <version>3.3.2.GA</version> </dependency> <dependency> <groupId>org.hibernate</groupId> <artifactId>ejb3-persistence</artifactId> <version>3.3.2.Beta1</version> </dependency> <dependency> <groupId>org.hibernate</groupId> <artifactId>hibernate-annotations</artifactId> <version>3.4.0.GA</version> </dependency> <dependency> <groupId>org.slf4j</groupId> <artifactId>slf4j-log4j12</artifactId> <version>1.5.2</version> </dependency> <dependency> <groupId>log4j</groupId> <artifactId>log4j</artifactId> <version>1.2.14</version> </dependency> </dependencies> <build> <plugins> <!-- compile with mvn assembly:assembly --> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-jar-plugin</artifactId> <version>2.2</version> </plugin> <!-- compile with mvn assembly:assembly --> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-assembly-plugin</artifactId> <version>2.2-beta-2</version> <configuration> <descriptorRefs> <descriptorRef>jar-with-dependencies</descriptorRef> </descriptorRefs> <archive> <manifest> <mainClass>sas.test.main.ExecuteMe</mainClass> </manifest> </archive> </configuration> <executions> <execution> <phase>package</phase> </execution> </executions> </plugin> <plugin> <!-- Force UTF-8 & Java-Version 1.6 --> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <configuration> <source>1.6</source> <target>1.6</target> <!--<encoding>utf-8</encoding>--> </configuration> </plugin> </plugins> </build> </project> and the persistence.xml, which, I promise, is in the classpath of the target: <?xml version="1.0" encoding="UTF-8"?> <persistence version="1.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd http://java.sun.com/xml/ns/persistence "> <persistence-unit name="EmployeeService" transaction-type="RESOURCE_LOCAL"> <provider>org.hibernate.ejb.HibernatePersistence</provider> <class>sas.test.model.Employee</class> <properties> <property name="javax.persistence.jdbc.driver" value="org.apache.derby.jdbc.EmbeddedDriver"/> <property name="hibernate.dialect" value="org.hibernate.dialect.DerbyDialect"/> <property name="hibernate.show_sql" value="true"/> <property name="javax.persistence.jdbc.url" value="jdbc:derby:webdb;create=true"/> </properties> </persistence-unit> </persistence> As you may have noticed from some commented code, I tried both, the Hibernate and the J2EE 6 implementation of JPA2.0, however, both failed. The above-mentioned code ends up with following error: log4j:WARN No appenders could be found for logger (org.hibernate.cfg.annotations.Version). log4j:WARN Please initialize the log4j system properly. Exception in thread "main" java.lang.UnsupportedOperationException: The user must supply a JDBC connection at org.hibernate.connection.UserSuppliedConnectionProvider.getConnection(UserSuppliedConnectionProvider.java:54) at org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:446) at org.hibernate.jdbc.ConnectionManager.getConnection(ConnectionManager.java:167) at org.hibernate.jdbc.JDBCContext.connection(JDBCContext.java:142) Any idea what's going wrong? Any "Hello World" maven/JPA2 demo that actually runs? I couldn't get any of those provided by google's search running. Thanx in advance.

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  • Swing object: first setText() gets "stuck" when using Mac Java SE 6

    - by Tim
    Hi there, I am a Java newbie trying to maintain an application that works fine under J2SE 5.0 (32- and 64-bit) but has a very specific problem when run under Java SE 6 64-bit: [Tims-MPB:~] tlynch% java -version java version "1.6.0_15" Java(TM) SE Runtime Environment (build 1.6.0_15-b03-226) Java HotSpot(TM) 64-Bit Server VM (build 14.1-b02-92, mixed mode) The application is cross-platform and reportedly works correctly on Java SE 6 under Windows, though I haven't been able to verify that myself. The program uses a JTextField for some text entry and a JLabel to indicate the text to be entered. The first time the showDialog() method is called to set the label text and display the dialog, it works correctly, but subsequent calls all result in the display of the label from the initial invocation rather than the one most recently specified via setText(). public void showDialog(String msgText) { System.out.println("set ChatDialog: " + msgText); jLabel1.setText(msgText); jLabel1.repaint(); // I added this; it didn't help System.out.println("get ChatDialog: " + jLabel1.getText()); super.setVisible(true); } [the full text of the class is provided below] The added printlns validate that expected text is passed to the label's setText() method and is confirmed by retrieving it using getText(), but what shows up on the screen/GUI is always the text from the very first time the method was called for the object. A similar issue is observed with a JTextArea used to label another dialog box. These problem are consistent across multiple Mac systems running Java SE 6 under OS 10.5.x and 10.6.x, but they are never observed when one reverts to J2SE 5.0. If there is some background information pertinent to this problem that I have omitted, please let me know. Any insights or advice appreciated. package gui; import java.awt.*; import java.awt.event.KeyEvent; import javax.swing.*; // Referenced classes of package gui: // MyJPanel, ChatDialog_jTextField1_keyAdapter, WarWindow public class ChatDialog extends JDialog { public ChatDialog(JFrame parent, WarWindow w) { super(parent, true); text = ""; borderLayout1 = new BorderLayout(); jPanel1 = new MyJPanel(); borderLayout2 = new BorderLayout(); jPanel2 = new MyJPanel(); jPanel3 = new MyJPanel(); jLabel1 = new JLabel(); jTextField1 = new JTextField(); warWindow = w; try { jbInit(); } catch(Exception exception) { System.out.println("Problem with ChatDialog init"); exception.printStackTrace(); } return; } public String getText() { return text; } void jTextField1_keyPressed(KeyEvent e) { int id = e.getKeyCode(); switch(id) { case 10: // '\n' text = jTextField1.getText(); setVisible(false); break; } } private void jbInit() throws Exception { setLocation(232, 450); setSize(560, 60); setModal(true); setResizable(false); setUndecorated(true); getContentPane().setLayout(borderLayout1); jPanel1.setLayout(borderLayout2); jPanel2.setMinimumSize(new Dimension(10, 20)); jPanel2.setPreferredSize(new Dimension(10, 20)); jLabel1.setPreferredSize(new Dimension(380, 15)); jLabel1.setHorizontalAlignment(0); jLabel1.setText("Chat Message"); jTextField1.setPreferredSize(new Dimension(520, 21)); jTextField1.setRequestFocusEnabled(false); jTextField1.addKeyListener(new ChatDialog_jTextField1_keyAdapter(this)); getContentPane().add(jPanel1, "Center"); jPanel1.add(jPanel2, "North"); jPanel2.add(jLabel1, null); jPanel1.add(jPanel3, "Center"); jPanel3.add(jTextField1, null); } public void setVisible(boolean b) { jTextField1.setText(""); super.setVisible(b); } public void showDialog(String msgText) { System.out.println("set ChatDialog: " + msgText); jLabel1.setText(msgText); jLabel1.repaint(); // I added this; it didn't help System.out.println("get ChatDialog: " + jLabel1.getText()); super.setVisible(true); } void this_keyPressed(KeyEvent e) { int id = e.getKeyCode(); switch(id) { case 10: // '\n' System.exit(88); break; } } BorderLayout borderLayout1; BorderLayout borderLayout2; JLabel jLabel1; JPanel jPanel1; JPanel jPanel2; JPanel jPanel3; JTextField jTextField1; String text; WarWindow warWindow; }

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  • Creating ActionEvent object for CustomButton in Java

    - by Crystal
    For a hw assignment, we were supposed to create a custom button to get familiar with swing and responding to events. We were also to make this button an event source which confuses me. I have an ArrayList to keep track of listeners that would register to listen to my CustomButton. What I am getting confused on is how to notify the listeners. My teacher hinted at having a notify and overriding actionPerformed which I tried doing, but then I wasn't sure how to create an ActionEvent object looking at the constructor documentation. The source, id, string all confuses me. Any help would be appreciated. Thanks! code: import java.awt.*; import java.awt.event.*; import javax.swing.*; import java.util.List; import java.util.ArrayList; public class CustomButton { public static void main(String[] args) { EventQueue.invokeLater(new Runnable() { public void run() { CustomButtonFrame frame = new CustomButtonFrame(); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setVisible(true); } }); } public void addActionListener(ActionListener al) { listenerList.add(al); } public void removeActionListener(ActionListener al) { listenerList.remove(al); } public void actionPerformed(ActionEvent e) { System.out.println("Button Clicked!"); } private void notifyListeners() { ActionEvent event = new ActionEvent(CONFUSED HERE!!!!; for (ActionListener action : listenerList) { action.actionPerfomed(event); } } List<ActionListener> listenerList = new ArrayList<ActionListener>(); } class CustomButtonFrame extends JFrame { // constructor for CustomButtonFrame public CustomButtonFrame() { setTitle("Custom Button"); CustomButtonSetup buttonSetup = new CustomButtonSetup(); this.add(buttonSetup); this.pack(); } } class CustomButtonSetup extends JComponent { public CustomButtonSetup() { ButtonAction buttonClicked = new ButtonAction(); this.addMouseListener(buttonClicked); } // because frame includes borders and insets, use this method public Dimension getPreferredSize() { return new Dimension(200, 200); } public void paintComponent(Graphics g) { Graphics2D g2 = (Graphics2D) g; // first triangle coords int x[] = new int[TRIANGLE_SIDES]; int y[] = new int[TRIANGLE_SIDES]; x[0] = 0; y[0] = 0; x[1] = 200; y[1] = 0; x[2] = 0; y[2] = 200; Polygon firstTriangle = new Polygon(x, y, TRIANGLE_SIDES); // second triangle coords x[0] = 0; y[0] = 200; x[1] = 200; y[1] = 200; x[2] = 200; y[2] = 0; Polygon secondTriangle = new Polygon(x, y, TRIANGLE_SIDES); g2.drawPolygon(firstTriangle); g2.setColor(firstColor); g2.fillPolygon(firstTriangle); g2.drawPolygon(secondTriangle); g2.setColor(secondColor); g2.fillPolygon(secondTriangle); // draw rectangle 10 pixels off border int s1[] = new int[RECT_SIDES]; int s2[] = new int[RECT_SIDES]; s1[0] = 5; s2[0] = 5; s1[1] = 195; s2[1] = 5; s1[2] = 195; s2[2] = 195; s1[3] = 5; s2[3] = 195; Polygon rectangle = new Polygon(s1, s2, RECT_SIDES); g2.drawPolygon(rectangle); g2.setColor(thirdColor); g2.fillPolygon(rectangle); } private class ButtonAction implements MouseListener { public void mousePressed(MouseEvent e) { System.out.println("Click!"); firstColor = Color.GRAY; secondColor = Color.WHITE; repaint(); } public void mouseReleased(MouseEvent e) { System.out.println("Released!"); firstColor = Color.WHITE; secondColor = Color.GRAY; repaint(); } public void mouseEntered(MouseEvent e) {} public void mouseExited(MouseEvent e) {} public void mouseClicked(MouseEvent e) {} } public static final int TRIANGLE_SIDES = 3; public static final int RECT_SIDES = 4; private Color firstColor = Color.WHITE; private Color secondColor = Color.DARK_GRAY; private Color thirdColor = Color.LIGHT_GRAY; }

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  • how to avoid temporaries when copying weakly typed object

    - by Truncheon
    Hi. I'm writing a series classes that inherit from a base class using virtual. They are INT, FLOAT and STRING objects that I want to use in a scripting language. I'm trying to implement weak typing, but I don't want STRING objects to return copies of themselves when used in the following way (instead I would prefer to have a reference returned which can be used in copying): a = "hello "; b = "world"; c = a + b; I have written the following code as a mock example: #include <iostream> #include <string> #include <cstdio> #include <cstdlib> std::string dummy("<int object cannot return string reference>"); struct BaseImpl { virtual bool is_string() = 0; virtual int get_int() = 0; virtual std::string get_string_copy() = 0; virtual std::string const& get_string_ref() = 0; }; struct INT : BaseImpl { int value; INT(int i = 0) : value(i) { std::cout << "constructor called\n"; } INT(BaseImpl& that) : value(that.get_int()) { std::cout << "copy constructor called\n"; } bool is_string() { return false; } int get_int() { return value; } std::string get_string_copy() { char buf[33]; sprintf(buf, "%i", value); return buf; } std::string const& get_string_ref() { return dummy; } }; struct STRING : BaseImpl { std::string value; STRING(std::string s = "") : value(s) { std::cout << "constructor called\n"; } STRING(BaseImpl& that) { if (that.is_string()) value = that.get_string_ref(); else value = that.get_string_copy(); std::cout << "copy constructor called\n"; } bool is_string() { return true; } int get_int() { return atoi(value.c_str()); } std::string get_string_copy() { return value; } std::string const& get_string_ref() { return value; } }; struct Base { BaseImpl* impl; Base(BaseImpl* p = 0) : impl(p) {} ~Base() { delete impl; } }; int main() { Base b1(new INT(1)); Base b2(new STRING("Hello world")); Base b3(new INT(*b1.impl)); Base b4(new STRING(*b2.impl)); std::cout << "\n"; std::cout << b1.impl->get_int() << "\n"; std::cout << b2.impl->get_int() << "\n"; std::cout << b3.impl->get_int() << "\n"; std::cout << b4.impl->get_int() << "\n"; std::cout << "\n"; std::cout << b1.impl->get_string_ref() << "\n"; std::cout << b2.impl->get_string_ref() << "\n"; std::cout << b3.impl->get_string_ref() << "\n"; std::cout << b4.impl->get_string_ref() << "\n"; std::cout << "\n"; std::cout << b1.impl->get_string_copy() << "\n"; std::cout << b2.impl->get_string_copy() << "\n"; std::cout << b3.impl->get_string_copy() << "\n"; std::cout << b4.impl->get_string_copy() << "\n"; return 0; } It was necessary to add an if check in the STRING class to determine whether its safe to request a reference instead of a copy: Script code: a = "test"; b = a; c = 1; d = "" + c; /* not safe to request reference by standard */ C++ code: STRING(BaseImpl& that) { if (that.is_string()) value = that.get_string_ref(); else value = that.get_string_copy(); std::cout << "copy constructor called\n"; } If was hoping there's a way of moving that if check into compile time, rather than run time.

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  • JSON object array to store data of a form in local storage temporary (PhoneGap project)

    - by Nadeesha
    I am building a data aqusition system using PhoneGap. .I am trying to store my form data temporary on local storage using JSON,Data should be visible after I close and reopen the application (after pressing Get Data button),But after I close it only the lastly entered record is visible This is my code <!DOCTYPE html> <html> <head> <title>Household Profile DB storage</title> <meta charset="utf-8"> <meta name="viewport" content="user-scalable=no, initial-scale=1, maximum-scale=1, minimum-scale=1,width=device-width" /> <link rel="stylesheet" href="jquery.mobile-1.4.2/jquery.mobile-1.4.2.min.css"> <link rel="stylesheet" href="css/table.css"> <script type="text/javascript" src="js/jquery-1.9.1.min.js"></script> <script type="text/javascript" src="jquery.mobile-1.4.2/jquery.mobile-1.4.2.min.js"></script> <script type="text/javascript" src="js/iscroll.js"></script> <script type="text/javascript" charset="utf-8"> function onDeviceReady() { persistData(homeId,owner,gramaND,contactNo,address,race); } function saveLocal(form){ if (window.localStorage) { var fhomeId = form.homeId.value, fowner = form.owner.value, fgramaND = form.gramaND.value, fcontactNo= form.contactNo.value, faddress = form.address.value, frace = form.race.value; alert("hi"); var highscores = [{"homeId": fhomeId, "owner":fowner, "gramaND":fgramaND, "contactNo":fcontactNo, "address":faddress, "race":frace}]; localStorage.setItem("highscores",JSON.stringify(highscores)); alert("The data has been stored successfully."); } else { alert("Your Browser does not support LocalStorage."); } } function readLocal(){ if (window.localStorage) { var scores =[]; //Get the highscores object scores = localStorage.getItem("highscores"); scores = JSON.parse(scores); for (i=0;i<scores.length;i++){ var text = "homeId :"+scores[i].homeId +"<br>"+ "owner:"+ scores[i].owner+"<br>"+ "address"+scores[i].address +"<br>"+ "gramaND"+scores[i].gramaND +"<br>"+ "contactNo"+scores[i].contactNo+"<br>" + '<Button value="DELETE" onclick="'+scores.splice(i, 0)+'><>/Button>'; var tbodyx = document.getElementsByTagName("tbody"); var tr=document.createElement("TR"); var td=document.createElement("TD"); td.innerHTML = text; tr.appendChild(td); tbody.appendChild(tr); } } } </script> </head> <body> <div data-role="page" id="page1"> <!--/header--> <div data-role="header" data-position="inline" data-theme="b"> <a href="#" data-icon="back" data-rel="back" title="Go back">Back</a> <h1>Household Profile</h1> <a href="index.html" data-icon="home">Menu</a> </div> <!--/header--> <div id="wrapper"> <form id="userInput" action ="" method="GET"> <div data-role="content"> <div data-role="fieldcontain"> <label > Home ID </label> <input class="inputClass" id="homeId" placeholder="H0001" value="" data-mini="true" type="text"> </div> <div data-role="fieldcontain"> <label > Owner </label> <input class="inputClass" id="owner" placeholder="Aberathne" value="" type="text"> </div> <div data-role="fieldcontain"> <label class="select">GramaNiladhari Division</label> <select class="inputClass" id="gramaND"> <option value="GramaNiladhari Division 1">GramaNiladhari Division 1</option> <option value="GramaNiladhari Division 2">GramaNiladhari Division 2</option> <option value="GramaNiladhari Division 3">GramaNiladhari Division 3</option> <option value="GramaNiladhari Division 4">GramaNiladhari Division 4</option> </select> </div> <div data-role="fieldcontain"> <label > Contact No </label> <input class="inputClass" id="contactNo" placeholder="071-9545-073" value="" type="number"> </div> <div data-role="fieldcontain"> <label >Address:</label> <textarea cols="40" rows="8" class="inputClass" id="address"></textarea> </div> <div class="ui-block-a"><button type="submit" data-theme="d">Location in a Map</button></div> <div data-role="fieldcontain"> <label >Race</label> <select class="inputClass" id="race"> <option value=" Sinhalese"> Sinhalese</option> <option value=" Sri Lanka Tamils"> Sri Lanka Tamils</option> <option value=" Moors"> Moors</option> <option value=" Indian Tamils "> Indian Tamils </option> <option value=" Malays "> Malays </option> <option value=" Burghers "> Burghers </option> </select> </div> <input class="buttonClass" type="button" value="Insert Data" onclick="saveLocal(this.form);"> </div> </form> </div> <input class="buttonClass" type="button" value="get Data" onclick="readLocal();"> <!-- <p id="dhomeId"></p> <p id="downer"></p> <p id="dgramaND"></p> <p id="dcontactNo"></p> <p id="daddress"></p> <p id="drace"></p>--> <table border="1"> <tbody id="tbody"> <tr><td>test1</td></tr> <tr><td>test2</td></tr> </tbody> </table> </div> </body> </html> Also I need to expand my code to edit and delete record from local storage.

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  • RuntimeError: maximum recursion depth exceeded while calling a Python object

    - by Bilal Basharat
    this error arises when i try to run the following test case which is written in models.py of my django app named 'administration' : from django.test import Client, TestCase from django.core import mail class ClientTest( TestCase ): fixtures = [ 'testdata.json' ] def test_get_register( self ): response = self.client.get( '/accounts/register/', {} ) self.assertEqual( response.status_code, 200 ) the error arises at this line specifically: response = self.client.get( '/accounts/register/', {} ) my django version is 1.2.1 and python 2.6 and satchmo version is 0.9.2-pre hg-unknown. I code in windows platform(xp sp2). The command to run test case is: python manage.py test administration the complete error log is as follow: site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 121, in by_host site = by_host(host=host[4:], id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 124, in by_host site = by_host(host = 'www.%s' % host, id_only=id_only) File "build\bdist.win32\egg\threaded_multihost\sites.py", line 101, in by_host site = Site.objects.get(domain=host) File "C:\django\django\db\models\manager.py", line 132, in get return self.get_query_set().get(*args, **kwargs) File "C:\django\django\db\models\query.py", line 336, in get num = len(clone) File "C:\django\django\db\models\query.py", line 81, in __len__ self._result_cache = list(self.iterator()) File "C:\django\django\db\models\query.py", line 269, in iterator for row in compiler.results_iter(): File "C:\django\django\db\models\sql\compiler.py", line 672, in results_iter for rows in self.execute_sql(MULTI): File "C:\django\django\db\models\sql\compiler.py", line 717, in execute_sql sql, params = self.as_sql() File "C:\django\django\db\models\sql\compiler.py", line 65, in as_sql where, w_params = self.query.where.as_sql(qn=qn, connection=self.connection) File "C:\django\django\db\models\sql\where.py", line 91, in as_sql sql, params = child.as_sql(qn=qn, connection=connection) File "C:\django\django\db\models\sql\where.py", line 94, in as_sql sql, params = self.make_atom(child, qn, connection) File "C:\django\django\db\models\sql\where.py", line 141, in make_atom lvalue, params = lvalue.process(lookup_type, params_or_value, connection) File "C:\django\django\db\models\sql\where.py", line 312, in process connection=connection, prepared=True) File "C:\django\django\db\models\fields\subclassing.py", line 53, in inner return func(*args, **kwargs) File "C:\django\django\db\models\fields\subclassing.py", line 53, in inner return func(*args, **kwargs) File "C:\django\django\db\models\fields\__init__.py", line 323, in get_db_prep _lookup return [self.get_db_prep_value(value, connection=connection, prepared=prepar ed)] File "C:\django\django\db\models\fields\subclassing.py", line 53, in inner return func(*args, **kwargs) File "C:\django\django\db\models\fields\subclassing.py", line 53, in inner return func(*args, **kwargs) RuntimeError: maximum recursion depth exceeded while calling a Python object ---------------------------------------------------------------------- Ran 7 tests in 48.453s FAILED (errors=1) Destroying test database 'default'...

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  • What's the best way to expose a Model object in a ViewModel?

    - by Angel
    In a WPF MVVM application, I exposed my model object into my viewModel by creating an instance of Model class (which cause dependency) into ViewModel. Instead of creating separate VM properties, I wrap the Model properties inside my ViewModel Property. My model is just an entity framework generated proxy class: public partial class TblProduct { public TblProduct() { this.TblPurchaseDetails = new HashSet<TblPurchaseDetail>(); this.TblPurchaseOrderDetails = new HashSet<TblPurchaseOrderDetail>(); this.TblSalesInvoiceDetails = new HashSet<TblSalesInvoiceDetail>(); this.TblSalesOrderDetails = new HashSet<TblSalesOrderDetail>(); } public int ProductId { get; set; } public string ProductCode { get; set; } public string ProductName { get; set; } public int CategoryId { get; set; } public string Color { get; set; } public Nullable<decimal> PurchaseRate { get; set; } public Nullable<decimal> SalesRate { get; set; } public string ImagePath { get; set; } public bool IsActive { get; set; } public virtual TblCompany TblCompany { get; set; } public virtual TblProductCategory TblProductCategory { get; set; } public virtual TblUser TblUser { get; set; } public virtual ICollection<TblPurchaseDetail> TblPurchaseDetails { get; set; } public virtual ICollection<TblPurchaseOrderDetail> TblPurchaseOrderDetails { get; set; } public virtual ICollection<TblSalesInvoiceDetail> TblSalesInvoiceDetails { get; set; } public virtual ICollection<TblSalesOrderDetail> TblSalesOrderDetails { get; set; } } Here is my ViewModel: public class ProductViewModel : WorkspaceViewModel { #region Constructor public ProductViewModel() { StartApp(); } #endregion //Constructor #region Properties private IProductDataService _dataService; public IProductDataService DataService { get { if (_dataService == null) { if (IsInDesignMode) { _dataService = new ProductDataServiceMock(); } else { _dataService = new ProductDataService(); } } return _dataService; } } //Get and set Model object private TblProduct _product; public TblProduct Product { get { return _product ?? (_product = new TblProduct()); } set { _product = value; } } #region Public Properties public int ProductId { get { return Product.ProductId; } set { if (Product.ProductId == value) { return; } Product.ProductId = value; RaisePropertyChanged("ProductId"); } } public string ProductName { get { return Product.ProductName; } set { if (Product.ProductName == value) { return; } Product.ProductName = value; RaisePropertyChanged(() => ProductName); } } private ObservableCollection<TblProduct> _productRecords; public ObservableCollection<TblProduct> ProductRecords { get { return _productRecords; } set { _productRecords = value; RaisePropertyChanged("ProductRecords"); } } //Selected Product private TblProduct _selectedProduct; public TblProduct SelectedProduct { get { return _selectedProduct; } set { _selectedProduct = value; if (_selectedProduct != null) { this.ProductId = _selectedProduct.ProductId; this.ProductCode = _selectedProduct.ProductCode; } RaisePropertyChanged("SelectedProduct"); } } #endregion //Public Properties #endregion // Properties #region Commands private ICommand _newCommand; public ICommand NewCommand { get { if (_newCommand == null) { _newCommand = new RelayCommand(() => ResetAll()); } return _newCommand; } } private ICommand _saveCommand; public ICommand SaveCommand { get { if (_saveCommand == null) { _saveCommand = new RelayCommand(() => Save()); } return _saveCommand; } } private ICommand _deleteCommand; public ICommand DeleteCommand { get { if (_deleteCommand == null) { _deleteCommand = new RelayCommand(() => Delete()); } return _deleteCommand; } } #endregion //Commands #region Methods private void StartApp() { LoadProductCollection(); } private void LoadProductCollection() { var q = DataService.GetAllProducts(); this.ProductRecords = new ObservableCollection<TblProduct>(q); } private void Save() { if (SelectedOperateMode == OperateModeEnum.OperateMode.New) { //Pass the Model object into Dataservice for save DataService.SaveProduct(this.Product); } else if (SelectedOperateMode == OperateModeEnum.OperateMode.Edit) { //Pass the Model object into Dataservice for Update DataService.UpdateProduct(this.Product); } ResetAll(); LoadProductCollection(); } #endregion //Methods } Here is my Service class: class ProductDataService:IProductDataService { /// <summary> /// Context object of Entity Framework model /// </summary> private MaizeEntities Context { get; set; } public ProductDataService() { Context = new MaizeEntities(); } public IEnumerable<TblProduct> GetAllProducts() { using(var context=new R_MaizeEntities()) { var q = from p in context.TblProducts where p.IsDel == false select p; return new ObservableCollection<TblProduct>(q); } } public void SaveProduct(TblProduct _product) { using(var context=new R_MaizeEntities()) { _product.LastModUserId = GlobalObjects.LoggedUserID; _product.LastModDttm = DateTime.Now; _product.CompanyId = GlobalObjects.CompanyID; context.TblProducts.Add(_product); context.SaveChanges(); } } public void UpdateProduct(TblProduct _product) { using (var context = new R_MaizeEntities()) { context.TblProducts.Attach(_product); context.Entry(_product).State = EntityState.Modified; _product.LastModUserId = GlobalObjects.LoggedUserID; _product.LastModDttm = DateTime.Now; _product.CompanyId = GlobalObjects.CompanyID; context.SaveChanges(); } } public void DeleteProduct(int _productId) { using (var context = new R_MaizeEntities()) { var product = (from c in context.TblProducts where c.ProductId == _productId select c).First(); product.LastModUserId = GlobalObjects.LoggedUserID; product.LastModDttm = DateTime.Now; product.IsDel = true; context.SaveChanges(); } } } I exposed my model object in my viewModel by creating an instance of it using new keyword, also I instantiated my DataService class in VM. I know this will cause a strong dependency. So: What's the best way to expose a Model object in a ViewModel? What's the best way to use DataService in VM?

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  • How do I report a missing package dependency during an upgrade?

    - by crasic
    A friend of mine (somewhat new to linux) recently upgraded from 10.10 to 11.04 and his OS broke from the upgrade. A few minutes of troubleshooting showed that the culprit was the PAE kernel that the upgrade decided to install since it determined he had 4GB of phyisical RAM. More specifically the upgrade forgot to install the linux-headers-generic-pae required by the closed source nvidia drivers. I'm not entirely sure how to report this bug to the devs. Its an easy fix (after booting into the non-pae kernel and installing the package everything worked), but they are encouraging users to use the built-in bug reporting system and I'm not entirely certain how to report update bugs.

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  • How to make a deb install only when the dependency is installed, or the conflicting packages aren't?

    - by adam
    I'm making a package for Cydia, but since it uses APT/dpkg, I thought I'd ask this question here. I want my package to only install if gsc.wildcat (represents an iPad) is installed, or if gsc.front-facing-camera (represents an iPhone 4/4S) is not installed. This setup would let the package only install on the 3GS or an iPad, but there's no package that represents a 3GS that I know of. It also requires iOS 5 (firmware (>= 5.0)). Here's an excerpt from my control file: Depends: gsc.wildcat, firmware (>= 5.0) Conflicts: gsc.front-facing-camera How can I do this with only Depends/Conflicts? (Please note that this question is about dpkg and not Cydia.)

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  • Are there any examples of a temporal field/object updater?

    - by Bryan Agee
    The system in question has numerous examples of temporal objects and fields--ones which are a certain variable at a certain point in time. An example of this would be someone's rate of pay--there are different answers depending on when you ask and what the constraints might be; eg, can there ever be more than one of a certain temporal object concurrently, etc. Ideally, there would be an object that handles those constraints when a new state/stateful object is introduced; when a new value is set, it would prevent creating negative ranges and overlaps. Martin Fowler has written some great material on this (such as this description of Temporal Objects) , but what I've found of it tends to be entirely theoretic, with no concrete implementations. PHP is the target language, but examples in any language would be most helpful.

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  • How do I pass an object location into a vertex shader?

    - by Greg Kassapidis
    I am using Blender Game Engine. I want to create a large flat plane, and deform it locally near a moving object. So far (despite being a beginner at shaders) I've written a vertex shader for the plane which moves the vertices to their correct positions (constant positions, for now). I cannot find a way to swap that constant location with an object's location updated every frame, while the shader is running. I am not even sure if it's possible. I only want to access a specific object's center from the shader.

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  • How to update dependency during runtime in my .NET application?

    - by Louis Rhys
    I have a server-client application. Sometimes the server is updated which requires some DLLs in the client to be updated as well (The DLLs are the dependencies of the main executable). For now, we have to close the client, manually deploy the DLLs, and then start the client again. This is kind of an inconvenience because the client is an automated application, so normally it doesn't need any user intervention. Is it possible for this to be done automatically without restart or user intervention? Like, the client would download the latest DLL, and replace the current one?

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  • How to detect whether an Object came to sleep at a specific position?

    - by Nils Riedemann
    I'm currently writing a small game with box2dweb and I need some direction for this: I'm throwing a Box and have to hit a specific place and trigger an event when the object that's been thrown isn't moving anymore, "fell asleep" so to say. What's the proper way / best practice for this? I'm currently thinking of asking the b2World whether an Object is within a specific AABB and then wait a few seconds, check if it's still there and then trigger the event. But this seems to me like the roundabout way and the object might still be moving inside of that AABB and eventually even drop out of the AABB.

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  • Efficient way of detecting a touched object in a game?

    - by Pin
    Imagine a Sims-like 2D game for a touch based mobile phone where one can interact with virtually any object in the scene. How can I efficiently detect which object is being touched by the player? In my short experience, looping through all the visible objects in the scene and checking if they're touched has so far done the job, but when there may be many many moving objects in the screen that sounds kind of inefficient isn't it? Keeping the visible moving objects list can consume time in itself as one may have to loop through all of them each frame. Other solutions I've thought are: Spatial hashing. Divide the screen as a grid and place the visible objects in the corresponding bucket. Detection of the clicked object is fast but there's additional overhead for placing the objects in the correct bucket each frame. Maintaining a quad-tree. Moving objects have to be rearranged all the time, the previous solution looks better. What is usually done in this case?

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  • how to serialize function depending on what instance of object calls it, if same instance call in a thread then do serialize else not

    - by LondonDreams
    I have a function which fetches and updates some record from db and I am trying to make sure each if the function is called by same instance of object(same Or different thread) then function should behave synchronized else its a call from different object instance function need not to be synchronized. I have tried it use a lock per client. That is, instead of synchronizing the method directly using explicit locking through lock objects using Map. function is like :- getAndUpdateMyHitCount(myObjId){ //go to db and get unique record by myObjId //fetch value , increment , save update } And this function may get call is same thread by different Or same object instance But as fetching and matching from Map is slow , Is there other optimized way to do this ? Found similar at this Question but dont feel that is optimized

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  • Could you give me an example of how to attach an object in Deleted state – I keep getting an exception [migrated]

    - by carewithl
    From MSDN : An object in the Deleted state can only be attached when the ObjectStateManager is already tracking the relationship instance. Could you give me an example of how to attach an object in the Deleted state. I tried the following and got "System.InvalidOperationException: The object being attached is in an added or deleted state. Relationships cannot be created for objects in this state". var contact = context.Contacts.First(); Console.WriteLine(contact.Addresses.Count()); // 2 var address = contact.Addresses.First(); context.Addresses.DeleteObject(address); contact.Addresses.Attach(address); // InvalidOperationException thank you

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  • How can I force apt to optimize the dependency tree for minimal download size?

    - by ObsessiveSSO?
    Some background information: As you may know, in a Debian package, there may be alternative dependencies, written in the CONTROL file as Depends: apache2|something-else, for example. How does apt select which dependencies to choose, and how can I override this so I can minimize download size? I'm on a slow connection on some locations and need it to use the smallest total download size. How can I force it to do so?

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  • Using the ASP.NET Cache to cache data in a Model or Business Object layer, without a dependency on System.Web in the layer - Part One.

    - by Rhames
    ASP.NET applications can make use of the System.Web.Caching.Cache object to cache data and prevent repeated expensive calls to a database or other store. However, ideally an application should make use of caching at the point where data is retrieved from the database, which typically is inside a Business Objects or Model layer. One of the key features of using a UI pattern such as Model-View-Presenter (MVP) or Model-View-Controller (MVC) is that the Model and Presenter (or Controller) layers are developed without any knowledge of the UI layer. Introducing a dependency on System.Web into the Model layer would break this independence of the Model from the View. This article gives a solution to this problem, using dependency injection to inject the caching implementation into the Model layer at runtime. This allows caching to be used within the Model layer, without any knowledge of the actual caching mechanism that will be used. Create a sample application to use the caching solution Create a test SQL Server database This solution uses a SQL Server database with the same Sales data used in my previous post on calculating running totals. The advantage of using this data is that it gives nice slow queries that will exaggerate the effect of using caching! To create the data, first create a new SQL database called CacheSample. Next run the following script to create the Sale table and populate it: USE CacheSample GO   CREATE TABLE Sale(DayCount smallint, Sales money) CREATE CLUSTERED INDEX ndx_DayCount ON Sale(DayCount) go INSERT Sale VALUES (1,120) INSERT Sale VALUES (2,60) INSERT Sale VALUES (3,125) INSERT Sale VALUES (4,40)   DECLARE @DayCount smallint, @Sales money SET @DayCount = 5 SET @Sales = 10   WHILE @DayCount < 5000  BEGIN  INSERT Sale VALUES (@DayCount,@Sales)  SET @DayCount = @DayCount + 1  SET @Sales = @Sales + 15  END Next create a stored procedure to calculate the running total, and return a specified number of rows from the Sale table, using the following script: USE [CacheSample] GO   SET ANSI_NULLS ON GO   SET QUOTED_IDENTIFIER ON GO   -- ============================================= -- Author:        Robin -- Create date: -- Description:   -- ============================================= CREATE PROCEDURE [dbo].[spGetRunningTotals]       -- Add the parameters for the stored procedure here       @HighestDayCount smallint = null AS BEGIN       -- SET NOCOUNT ON added to prevent extra result sets from       -- interfering with SELECT statements.       SET NOCOUNT ON;         IF @HighestDayCount IS NULL             SELECT @HighestDayCount = MAX(DayCount) FROM dbo.Sale                   DECLARE @SaleTbl TABLE (DayCount smallint, Sales money, RunningTotal money)         DECLARE @DayCount smallint,                   @Sales money,                   @RunningTotal money         SET @RunningTotal = 0       SET @DayCount = 0         DECLARE rt_cursor CURSOR       FOR       SELECT DayCount, Sales       FROM Sale       ORDER BY DayCount         OPEN rt_cursor         FETCH NEXT FROM rt_cursor INTO @DayCount,@Sales         WHILE @@FETCH_STATUS = 0 AND @DayCount <= @HighestDayCount        BEGIN        SET @RunningTotal = @RunningTotal + @Sales        INSERT @SaleTbl VALUES (@DayCount,@Sales,@RunningTotal)        FETCH NEXT FROM rt_cursor INTO @DayCount,@Sales        END         CLOSE rt_cursor       DEALLOCATE rt_cursor         SELECT DayCount, Sales, RunningTotal       FROM @SaleTbl   END   GO   Create the Sample ASP.NET application In Visual Studio create a new solution and add a class library project called CacheSample.BusinessObjects and an ASP.NET web application called CacheSample.UI. The CacheSample.BusinessObjects project will contain a single class to represent a Sale data item, with all the code to retrieve the sales from the database included in it for simplicity (normally I would at least have a separate Repository or other object that is responsible for retrieving data, and probably a data access layer as well, but for this sample I want to keep it simple). The C# code for the Sale class is shown below: using System; using System.Collections.Generic; using System.Data; using System.Data.SqlClient;   namespace CacheSample.BusinessObjects {     public class Sale     {         public Int16 DayCount { get; set; }         public decimal Sales { get; set; }         public decimal RunningTotal { get; set; }           public static IEnumerable<Sale> GetSales(int? highestDayCount)         {             List<Sale> sales = new List<Sale>();               SqlParameter highestDayCountParameter = new SqlParameter("@HighestDayCount", SqlDbType.SmallInt);             if (highestDayCount.HasValue)                 highestDayCountParameter.Value = highestDayCount;             else                 highestDayCountParameter.Value = DBNull.Value;               string connectionStr = System.Configuration.ConfigurationManager .ConnectionStrings["CacheSample"].ConnectionString;               using(SqlConnection sqlConn = new SqlConnection(connectionStr))             using (SqlCommand sqlCmd = sqlConn.CreateCommand())             {                 sqlCmd.CommandText = "spGetRunningTotals";                 sqlCmd.CommandType = CommandType.StoredProcedure;                 sqlCmd.Parameters.Add(highestDayCountParameter);                   sqlConn.Open();                   using (SqlDataReader dr = sqlCmd.ExecuteReader())                 {                     while (dr.Read())                     {                         Sale newSale = new Sale();                         newSale.DayCount = dr.GetInt16(0);                         newSale.Sales = dr.GetDecimal(1);                         newSale.RunningTotal = dr.GetDecimal(2);                           sales.Add(newSale);                     }                 }             }               return sales;         }     } }   The static GetSale() method makes a call to the spGetRunningTotals stored procedure and then reads each row from the returned SqlDataReader into an instance of the Sale class, it then returns a List of the Sale objects, as IEnnumerable<Sale>. A reference to System.Configuration needs to be added to the CacheSample.BusinessObjects project so that the connection string can be read from the web.config file. In the CacheSample.UI ASP.NET project, create a single web page called ShowSales.aspx, and make this the default start up page. This page will contain a single button to call the GetSales() method and a label to display the results. The html mark up and the C# code behind are shown below: ShowSales.aspx <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="ShowSales.aspx.cs" Inherits="CacheSample.UI.ShowSales" %>   <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">   <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server">     <title>Cache Sample - Show All Sales</title> </head> <body>     <form id="form1" runat="server">     <div>         <asp:Button ID="btnTest1" runat="server" onclick="btnTest1_Click"             Text="Get All Sales" />         &nbsp;&nbsp;&nbsp;         <asp:Label ID="lblResults" runat="server"></asp:Label>         </div>     </form> </body> </html>   ShowSales.aspx.cs using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls;   using CacheSample.BusinessObjects;   namespace CacheSample.UI {     public partial class ShowSales : System.Web.UI.Page     {         protected void Page_Load(object sender, EventArgs e)         {         }           protected void btnTest1_Click(object sender, EventArgs e)         {             System.Diagnostics.Stopwatch stopWatch = new System.Diagnostics.Stopwatch();             stopWatch.Start();               var sales = Sale.GetSales(null);               var lastSales = sales.Last();               stopWatch.Stop();               lblResults.Text = string.Format( "Count of Sales: {0}, Last DayCount: {1}, Total Sales: {2}. Query took {3} ms", sales.Count(), lastSales.DayCount, lastSales.RunningTotal, stopWatch.ElapsedMilliseconds);         }       } }   Finally we need to add a connection string to the CacheSample SQL Server database, called CacheSample, to the web.config file: <?xmlversion="1.0"?>   <configuration>    <connectionStrings>     <addname="CacheSample"          connectionString="data source=.\SQLEXPRESS;Integrated Security=SSPI;Initial Catalog=CacheSample"          providerName="System.Data.SqlClient" />  </connectionStrings>    <system.web>     <compilationdebug="true"targetFramework="4.0" />  </system.web>   </configuration>   Run the application and click the button a few times to see how long each call to the database takes. On my system, each query takes about 450ms. Next I shall look at a solution to use the ASP.NET caching to cache the data returned by the query, so that subsequent requests to the GetSales() method are much faster. Adding Data Caching Support I am going to create my caching support in a separate project called CacheSample.Caching, so the next step is to add a class library to the solution. We shall be using the application configuration to define the implementation of our caching system, so we need a reference to System.Configuration adding to the project. ICacheProvider<T> Interface The first step in adding caching to our application is to define an interface, called ICacheProvider, in the CacheSample.Caching project, with methods to retrieve any data from the cache or to retrieve the data from the data source if it is not present in the cache. Dependency Injection will then be used to inject an implementation of this interface at runtime, allowing the users of the interface (i.e. the CacheSample.BusinessObjects project) to be completely unaware of how the caching is actually implemented. As data of any type maybe retrieved from the data source, it makes sense to use generics in the interface, with a generic type parameter defining the data type associated with a particular instance of the cache interface implementation. The C# code for the ICacheProvider interface is shown below: using System; using System.Collections.Generic;   namespace CacheSample.Caching {     public interface ICacheProvider     {     }       public interface ICacheProvider<T> : ICacheProvider     {         T Fetch(string key, Func<T> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry);           IEnumerable<T> Fetch(string key, Func<IEnumerable<T>> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry);     } }   The empty non-generic interface will be used as a type in a Dictionary generic collection later to store instances of the ICacheProvider<T> implementation for reuse, I prefer to use a base interface when doing this, as I think the alternative of using object makes for less clear code. The ICacheProvider<T> interface defines two overloaded Fetch methods, the difference between these is that one will return a single instance of the type T and the other will return an IEnumerable<T>, providing support for easy caching of collections of data items. Both methods will take a key parameter, which will uniquely identify the cached data, a delegate of type Func<T> or Func<IEnumerable<T>> which will provide the code to retrieve the data from the store if it is not present in the cache, and absolute or relative expiry policies to define when a cached item should expire. Note that at present there is no support for cache dependencies, but I shall be showing a method of adding this in part two of this article. CacheProviderFactory Class We need a mechanism of creating instances of our ICacheProvider<T> interface, using Dependency Injection to get the implementation of the interface. To do this we shall create a CacheProviderFactory static class in the CacheSample.Caching project. This factory will provide a generic static method called GetCacheProvider<T>(), which shall return instances of ICacheProvider<T>. We can then call this factory method with the relevant data type (for example the Sale class in the CacheSample.BusinessObject project) to get a instance of ICacheProvider for that type (e.g. call CacheProviderFactory.GetCacheProvider<Sale>() to get the ICacheProvider<Sale> implementation). The C# code for the CacheProviderFactory is shown below: using System; using System.Collections.Generic;   using CacheSample.Caching.Configuration;   namespace CacheSample.Caching {     public static class CacheProviderFactory     {         private static Dictionary<Type, ICacheProvider> cacheProviders = new Dictionary<Type, ICacheProvider>();         private static object syncRoot = new object();           ///<summary>         /// Factory method to create or retrieve an implementation of the  /// ICacheProvider interface for type <typeparamref name="T"/>.         ///</summary>         ///<typeparam name="T">  /// The type that this cache provider instance will work with  ///</typeparam>         ///<returns>An instance of the implementation of ICacheProvider for type  ///<typeparamref name="T"/>, as specified by the application  /// configuration</returns>         public static ICacheProvider<T> GetCacheProvider<T>()         {             ICacheProvider<T> cacheProvider = null;             // Get the Type reference for the type parameter T             Type typeOfT = typeof(T);               // Lock the access to the cacheProviders dictionary             // so multiple threads can work with it             lock (syncRoot)             {                 // First check if an instance of the ICacheProvider implementation  // already exists in the cacheProviders dictionary for the type T                 if (cacheProviders.ContainsKey(typeOfT))                     cacheProvider = (ICacheProvider<T>)cacheProviders[typeOfT];                 else                 {                     // There is not already an instance of the ICacheProvider in       // cacheProviders for the type T                     // so we need to create one                       // Get the Type reference for the application's implementation of       // ICacheProvider from the configuration                     Type cacheProviderType = Type.GetType(CacheProviderConfigurationSection.Current. CacheProviderType);                     if (cacheProviderType != null)                     {                         // Now get a Type reference for the Cache Provider with the                         // type T generic parameter                         Type typeOfCacheProviderTypeForT = cacheProviderType.MakeGenericType(new Type[] { typeOfT });                         if (typeOfCacheProviderTypeForT != null)                         {                             // Create the instance of the Cache Provider and add it to // the cacheProviders dictionary for future use                             cacheProvider = (ICacheProvider<T>)Activator. CreateInstance(typeOfCacheProviderTypeForT);                             cacheProviders.Add(typeOfT, cacheProvider);                         }                     }                 }             }               return cacheProvider;                 }     } }   As this code uses Activator.CreateInstance() to create instances of the ICacheProvider<T> implementation, which is a slow process, the factory class maintains a Dictionary of the previously created instances so that a cache provider needs to be created only once for each type. The type of the implementation of ICacheProvider<T> is read from a custom configuration section in the application configuration file, via the CacheProviderConfigurationSection class, which is described below. CacheProviderConfigurationSection Class The implementation of ICacheProvider<T> will be specified in a custom configuration section in the application’s configuration. To handle this create a folder in the CacheSample.Caching project called Configuration, and add a class called CacheProviderConfigurationSection to this folder. This class will extend the System.Configuration.ConfigurationSection class, and will contain a single string property called CacheProviderType. The C# code for this class is shown below: using System; using System.Configuration;   namespace CacheSample.Caching.Configuration {     internal class CacheProviderConfigurationSection : ConfigurationSection     {         public static CacheProviderConfigurationSection Current         {             get             {                 return (CacheProviderConfigurationSection) ConfigurationManager.GetSection("cacheProvider");             }         }           [ConfigurationProperty("type", IsRequired=true)]         public string CacheProviderType         {             get             {                 return (string)this["type"];             }         }     } }   Adding Data Caching to the Sales Class We now have enough code in place to add caching to the GetSales() method in the CacheSample.BusinessObjects.Sale class, even though we do not yet have an implementation of the ICacheProvider<T> interface. We need to add a reference to the CacheSample.Caching project to CacheSample.BusinessObjects so that we can use the ICacheProvider<T> interface within the GetSales() method. Once the reference is added, we can first create a unique string key based on the method name and the parameter value, so that the same cache key is used for repeated calls to the method with the same parameter values. Then we get an instance of the cache provider for the Sales type, using the CacheProviderFactory, and pass the existing code to retrieve the data from the database as the retrievalMethod delegate in a call to the Cache Provider Fetch() method. The C# code for the modified GetSales() method is shown below: public static IEnumerable<Sale> GetSales(int? highestDayCount) {     string cacheKey = string.Format("CacheSample.BusinessObjects.GetSalesWithCache({0})", highestDayCount);       return CacheSample.Caching.CacheProviderFactory. GetCacheProvider<Sale>().Fetch(cacheKey,         delegate()         {             List<Sale> sales = new List<Sale>();               SqlParameter highestDayCountParameter = new SqlParameter("@HighestDayCount", SqlDbType.SmallInt);             if (highestDayCount.HasValue)                 highestDayCountParameter.Value = highestDayCount;             else                 highestDayCountParameter.Value = DBNull.Value;               string connectionStr = System.Configuration.ConfigurationManager. ConnectionStrings["CacheSample"].ConnectionString;               using (SqlConnection sqlConn = new SqlConnection(connectionStr))             using (SqlCommand sqlCmd = sqlConn.CreateCommand())             {                 sqlCmd.CommandText = "spGetRunningTotals";                 sqlCmd.CommandType = CommandType.StoredProcedure;                 sqlCmd.Parameters.Add(highestDayCountParameter);                   sqlConn.Open();                   using (SqlDataReader dr = sqlCmd.ExecuteReader())                 {                     while (dr.Read())                     {                         Sale newSale = new Sale();                         newSale.DayCount = dr.GetInt16(0);                         newSale.Sales = dr.GetDecimal(1);                         newSale.RunningTotal = dr.GetDecimal(2);                           sales.Add(newSale);                     }                 }             }               return sales;         },         null,         new TimeSpan(0, 10, 0)); }     This example passes the code to retrieve the Sales data from the database to the Cache Provider as an anonymous method, however it could also be written as a lambda. The main advantage of using an anonymous function (method or lambda) is that the code inside the anonymous function can access the parameters passed to the GetSales() method. Finally the absolute expiry is set to null, and the relative expiry set to 10 minutes, to indicate that the cache entry should be removed 10 minutes after the last request for the data. As the ICacheProvider<T> has a Fetch() method that returns IEnumerable<T>, we can simply return the results of the Fetch() method to the caller of the GetSales() method. This should be all that is needed for the GetSales() method to now retrieve data from a cache after the first time the data has be retrieved from the database. Implementing a ASP.NET Cache Provider The final step is to actually implement the ICacheProvider<T> interface, and add the implementation details to the web.config file for the dependency injection. The cache provider implementation needs to have access to System.Web. Therefore it could be placed in the CacheSample.UI project, or in its own project that has a reference to System.Web. Implementing the Cache Provider in a separate project is my favoured approach. Create a new project inside the solution called CacheSample.CacheProvider, and add references to System.Web and CacheSample.Caching to this project. Add a class to the project called AspNetCacheProvider. Make the class a generic class by adding the generic parameter <T> and indicate that the class implements ICacheProvider<T>. The C# code for the AspNetCacheProvider class is shown below: using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.Caching;   using CacheSample.Caching;   namespace CacheSample.CacheProvider {     public class AspNetCacheProvider<T> : ICacheProvider<T>     {         #region ICacheProvider<T> Members           public T Fetch(string key, Func<T> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry)         {             return FetchAndCache<T>(key, retrieveData, absoluteExpiry, relativeExpiry);         }           public IEnumerable<T> Fetch(string key, Func<IEnumerable<T>> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry)         {             return FetchAndCache<IEnumerable<T>>(key, retrieveData, absoluteExpiry, relativeExpiry);         }           #endregion           #region Helper Methods           private U FetchAndCache<U>(string key, Func<U> retrieveData, DateTime? absoluteExpiry, TimeSpan? relativeExpiry)         {             U value;             if (!TryGetValue<U>(key, out value))             {                 value = retrieveData();                 if (!absoluteExpiry.HasValue)                     absoluteExpiry = Cache.NoAbsoluteExpiration;                   if (!relativeExpiry.HasValue)                     relativeExpiry = Cache.NoSlidingExpiration;                   HttpContext.Current.Cache.Insert(key, value, null, absoluteExpiry.Value, relativeExpiry.Value);             }             return value;         }           private bool TryGetValue<U>(string key, out U value)         {             object cachedValue = HttpContext.Current.Cache.Get(key);             if (cachedValue == null)             {                 value = default(U);                 return false;             }             else             {                 try                 {                     value = (U)cachedValue;                     return true;                 }                 catch                 {                     value = default(U);                     return false;                 }             }         }           #endregion       } }   The two interface Fetch() methods call a private method called FetchAndCache(). This method first checks for a element in the HttpContext.Current.Cache with the specified cache key, and if so tries to cast this to the specified type (either T or IEnumerable<T>). If the cached element is found, the FetchAndCache() method simply returns it. If it is not found in the cache, the method calls the retrievalMethod delegate to get the data from the data source, and then adds this to the HttpContext.Current.Cache. The final step is to add the AspNetCacheProvider class to the relevant custom configuration section in the CacheSample.UI.Web.Config file. To do this there needs to be a <configSections> element added as the first element in <configuration>. This will match a custom section called <cacheProvider> with the CacheProviderConfigurationSection. Then we add a <cacheProvider> element, with a type property set to the fully qualified assembly name of the AspNetCacheProvider class, as shown below: <?xmlversion="1.0"?>   <configuration>  <configSections>     <sectionname="cacheProvider" type="CacheSample.Base.Configuration.CacheProviderConfigurationSection, CacheSample.Base" />  </configSections>    <connectionStrings>     <addname="CacheSample"          connectionString="data source=.\SQLEXPRESS;Integrated Security=SSPI;Initial Catalog=CacheSample"          providerName="System.Data.SqlClient" />  </connectionStrings>    <cacheProvidertype="CacheSample.CacheProvider.AspNetCacheProvider`1, CacheSample.CacheProvider, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null">  </cacheProvider>    <system.web>     <compilationdebug="true"targetFramework="4.0" />  </system.web>   </configuration>   One point to note is that the fully qualified assembly name of the AspNetCacheProvider class includes the notation `1 after the class name, which indicates that it is a generic class with a single generic type parameter. The CacheSample.UI project needs to have references added to CacheSample.Caching and CacheSample.CacheProvider so that the actual application is aware of the relevant cache provider implementation. Conclusion After implementing this solution, you should have a working cache provider mechanism, that will allow the middle and data access layers to implement caching support when retrieving data, without any knowledge of the actually caching implementation. If the UI is not ASP.NET based, if for example it is Winforms or WPF, the implementation of ICacheProvider<T> would be written around whatever technology is available. It could even be a standalone caching system that takes full responsibility for adding and removing items from a global store. The next part of this article will show how this caching mechanism may be extended to provide support for cache dependencies, such as the System.Web.Caching.SqlCacheDependency. Another possible extension would be to cache the cache provider implementations instead of storing them in a static Dictionary in the CacheProviderFactory. This would prevent a build up of seldom used cache providers in the application memory, as they could be removed from the cache if not used often enough, although in reality there are probably unlikely to be vast numbers of cache provider implementation instances, as most applications do not have a massive number of business object or model types.

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