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• Is ADO.NET Entity framework database schema update possible ?

  - by fyasar

  Hi All I'm working on proof of concept application like crm and i need your some advice. My application's data layer completely dynamic and run onto EF 3.5. When the user update the entity, change relation or add new column to the database, first i'm planning make for these with custom classes. After I rebuild my database model layer with new changes during the application runtime. And my model layer tie with tightly coupled to my project for easy reflecting model layer changes (It connected to my project via interfaces and loading onto to application domain in the runtime). I need to create dynamic entities, create entity relations and modify them during the runtime after that i need to create change database script for updating database schema. I know ADO.NET team says "we will be able to provide this property in EF 4.0", but i don't need to wait for them. How can i update database changes during the runtime via EF 3.5 ? For example, i need to create new entity or need to change some entity schema, add new properties or change property types after than how can apply these changes on the physical database schema ? Any ideas ?

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• Java: easiest way to package both Java 1.5 and 1.6 code

  - by WizardOfOdds

  I want to package a piece of code that absolutely must run on Java 1.5. There's one part of the code where the program can be "enhanced" if the VM is an 1.6 VM. Basically it's this method: private long[] findDeadlockedThreads() { // JDK 1.5 only supports the findMonitorDeadlockedThreads() // method, so you need to comment out the following three lines if (mbean.isSynchronizerUsageSupported()) return mbean.findDeadlockedThreads(); else return mbean.findMonitorDeadlockedThreads(); } What would be easiest way to have this compile on 1.5 and yet do the 1.6 method calls when on 1.6 ? In the past I've done something similar by compiling a unique 1.6 class that I would package with my app and instantiate using a ClassLoader when on 1.6 (because an 1.6 JVM is perfectly fine mixing 0x32 and 0x31 classes), but I think it's a bit overkill (and a bit painful because during the build process you have to build both 0x31 and 0x32 .class files). How should I go if I wanted to compile the above method on 1.5? Maybe using reflection but then how (I'm not familiar at all with reflection) Note: if you're curious, the above method comes from this article: http://www.javaspecialists.eu/archive/Issue130.html (but I don't want to "comment the three lines" like in the article, I want this to compile and run on both 1.5 and 1.6)

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• How to name multiple versioned ServiceContracts in the same WCF service?

  - by Tor Hovland

  When you have to introduce a breaking change in a ServiceContract, a best practice is to keep the old one and create a new one, and use some version identifier in the namespace. If I understand this correctly, I should be able to do the following: [ServiceContract(Namespace = "http://foo.com/2010/01/14")] public interface IVersionedService { [OperationContract] string WriteGreeting(Person person); } [ServiceContract(Name = "IVersionedService", Namespace = "http://foo.com/2010/02/21")] public interface IVersionedService2 { [OperationContract(Name = "WriteGreeting")] Greeting WriteGreeting2(Person2 person); } With this I can create a service that supports both versions. This actually works, and it looks fine when testing from soapUI. However, when I create a client in Visual Studio using "Add Service Reference", VS disregards the namespaces and simply sees two interfaces with the same name. In order to differentiate them, VS adds "1" to the name of one of them. I end up with proxies called ServiceReference.VersionedServiceClient and ServiceReference.VersionedService1Client Now it's not easy for anybody to see which is the newer version. Should I give the interfaces different names? E.g IVersionedService1 IVersionedService2 or IVersionedService/2010/01/14 IVersionedService/2010/02/21 Doesn't this defeat the purpose of the namespace? Should I put them in different service classes and get a unique URL for each version?

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• When is someone else's code I use from the internet "mine"?

  - by robault

  I'm building a library from methods that I've found on the internet. Some are free to use or modify with no requirements, others say that if I leave a comment in the code it's okay to use, others say when I use the code I have to attribute the use of someone's code in my application (in the credits for my app I guess). What I've been doing is reorganizing classes, renaming methods, adding descriptions (code comments), renaming the parameters and names inside the methods to something meaningful, optimizing loops if applicable, changing return types, adding try/catch/throw blocks, adding parameter checks and cleaning up resources in the methods. For example; I didn't come up with the algorithm for blurring a Bitmap but I've taken the basic example of iterating through the pixels and turned it into a decent library method (applying the aforementioned modifications). I understand how to go about building it now myself but I didn't actually hit the keystrokes to make it and I couldn't have come up with it before learning from their example. What about code people get in answers on Stackoverflow or examples from Codeproject? At what point can I drop their requirements because at n% their code became mine? FWIW I intend on using the libraries to create products that I will sell.

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• Where do I put jar files in Tomcat 6?

  - by Simon

  I am having trouble getting my JSP page to load a Java class which is in a jar file. The message I get appears to indicate a class not found exception: Jan 6, 2011 12:21:45 PM org.apache.catalina.core.StandardWrapperValve invoke SEVERE: Servlet.service() for servlet jsp threw exception org.apache.jasper.JasperException: Unable to compile class for JSP: An error occurred at line: 72 in the jsp file: /xmlloader.jsp FactArray cannot be resolved to a type 69: sourceType = "1"; 70: } 71: 72: FactArray fa = new FactArray(); 73: Fact f; 74: 75: /***********************/ The Type FactArray is one of my classes in a package com.mypackage.fact.FactArray which exists in myjar.jar. myjar.jar is a separate Java project (using NetBeans, but I don't think that's relevant). I include the package in my JSP as follows: <%@ page import="com.mypackage.fact.*" %> I deploy my web site and JSPs into Tomcat 6 as a WAR file. I include myjar.jar in that WAR in WEB-INF/lib but that doesn't work. I tried putting myjar.jar in my tomcat/lib folder, but that doesn't work either. I have bounced the server several times between changes. I have read a whole bunch of questions on here which say "put it in WEB-INF/lib" but that isn't working, so I'm asking my own question. Where do I need to put common JAR files so they get picked up by Tomcat?

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• Dynamically added JTable not displaying

  - by Graza

  Java Newbie here. I have a JFrame that I added to my netbeans project, and I've added the following method to it, which creates a JTable. Problem is, for some reason when I call this method, the JTable isn't displayed. Any suggestions? public void showFromVectors(Vector colNames, Vector data) { jt = new javax.swing.JTable(data, colNames); sp = new javax.swing.JScrollPane(jt); //NB: "this" refers to my class DBGridForm, which extends JFrame this.add(sp,java.awt.BorderLayout.CENTER); this.setSize(640,480); } The method is called in the following context: DBGridForm gf = new DBGridForm(); //DBGridForm extends JFrame DBReader.outMatchesTable(gf); gf.setVisible(true); ... where DBReader.outMatchesTable() is defined as static public void outMatchesTable(DBGridForm gf) { DBReader ddb = new DBReader(); ddb.readMatchesTable(null); gf.showFromVectors(ddb.lastRsltColNames, ddb.lastRsltData); } My guess is I'm overlooking something, either about the swing classes I'm using, or about Java. Any ideas?

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• Linker, Libraries & Directories Information

  - by m00st

  I've finished both my C++ 1/2 classes and we did not cover anything on Linking to libraries or adding additional libraries to C++ code. I've been having a hay-day trying to figure this out; I've been unable to find basic information linking to objects. Initially I thought the problem was the IDE (Netbeans; and Code::Blocks). However I've been unable to get wxWidgets and GTKMM setup. Can someone point me in the right direction on the terminology and basic information about #including files and linking files in a Cpp application? Basically I want/need to know everything in regards to this process. The difference between .dll, .lib, .o, .lib.a, .dll.a. The difference between a .h and a "library" (.dll, .lib correct?) I understand I need to read the compiler documentation I am using; however all compilers (that I know of) use linker and headers; I need to learn this information. Please point me in the right direction! :] So far on my quest I've found out: Linker links libraries already compiled to your project. .a files are static libraries (.lib in windows) .dll in windows is a shared library (.so in *nix) Thanks

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• Intellisense on custom types in Iron Python

  - by Anish Patel

  Hi everybody, I'm just starting to play around with IronPython and am having a hard time using it with custom types created in C#. I can get IronPython to load in assemblies from C# classes, but I'm struggling without the help of intellisense. If I have a class in C# as defined below, how can I make it so that IronPython will be able to see the methods/properties that are available in it? public class Person { public string Name { get; set; } public int Age{ get; set; } public double Weight{ get; set; } public double Height { get; set; } public double CalculateBMI() { return Weight/Math.Pow(Height, 2); } } In Iron python I'd instance a Person object as follows: newPerson = Person() newPerson.Name = 'John' newPerson.Age = 25 newPerson.Weight = 75 newPerson.Height = 1.70 newPerson.CalculateBMI() The thing that is annoying me is that I want to be able to say newPerson = Person() And then be able to see all the methods and properties associated with the person object whenever I type: newPerson. Anyone have any ideas if this can be done?

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• Working around "one executable per project" in Visual C# for many small test programs

  - by Kevin Ivarsen

  When working with Visual Studio in general (or Visual C# Express in my particular case), it looks like each project can be configured to produce only one output - e.g. a single executable or a library. I'm working on a project that consists of a shared library and a few application, and I already have one project in my solution for each of those. However, during development I find it useful to write small example programs that can run one small subsystem in isolation (at a level that doesn't belong in the unit tests). Is there a good way to handle this in Visual Studio? I'd like to avoid adding several dozen separate projects to my solution for each small test program I write, especially when these programs will typically be less than 100 lines of code. I'm hoping to find something that lets me continue to work in Visual Studio and use its build system (rather than moving to something like NAnt). I could foresee the answer being something like: A way of setting this up in Visual Studio that I haven't found yet A GUI like NUnit's graphical runner that searches an assembly for classes with defined Main() functions that you can select and run A command line tool that lets you specify an assembly and a class with a Main function to run

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• return an ArrayList method

  - by Bopeng Liu

  This is a drive method for two other classes. which i posted here http://codereview.stackexchange.com/questions/33148/book-program-with-arraylist I need some help for the private static ArrayList getAuthors(String authors) method. I am kind a beginner. so please help me finish this drive method. or give me some directions. Instruction some of the elements of the allAuthors array contain asterisks “*” between two authors names. The getAuthors method uses this asterisk as a delimiter between names to store them separately in the returned ArrayList of Strings. import java.util.ArrayList; public class LibraryDrive { public static void main(String[] args) { String[] titles = { "The Hobbit", "Acer Dumpling", "A Christmas Carol", "Marley and Me", "Building Java Programs", "Java, How to Program" }; String[] allAuthors = { "Tolkien, J.R.", "Doofus, Robert", "Dickens, Charles", "Remember, SomeoneIdont", "Reges, Stuart*Stepp, Marty", "Deitel, Paul*Deitel, Harvery" }; ArrayList<String> authors = new ArrayList<String>(); ArrayList<Book> books = new ArrayList<Book>(); for (int i = 0; i < titles.length; i++) { authors = getAuthors(allAuthors[i]); Book b = new Book(titles[i], authors); books.add(b); authors.remove(0); } Library lib = new Library(books); System.out.println(lib); lib.sort(); System.out.println(lib); } private static ArrayList<String> getAuthors(String authors) { ArrayList books = new ArrayList<String>(); // need help here. return books; } }

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• Jquery class changing works, but doesn't effect another function like it should

  - by Qwibble

  So I have content boxes that close and expand when you click an arrow. The content box has two classes for telling whether it is open or closed (.box_open, .box_closed). A hover function is assigned to box_open so when it is open and you hover over the header, the arrow appears. However, I don't want this to happen when the box is closed, as I want to arrow to remain visible when the box is closed. When the box closes, the box_open class is removed, but the function assigned to that class still works. Here's the jquery code for the two functions. You can also see them in the head of the demo below. // Display Arrow on Box Header Hover $(".box_open").hover( function () { $(this).find('a').show(); }, function () { $(this).find('a').hide(); } ); // Open and Close Boxes: $(".box_header a").click( function () { $(this).parent().next('.box_border').stop().toggle(); $(this).parent().toggleClass("box_open"); $(this).parent().toggleClass("box_closed"); return false; } ); Can anyone take a look at what the problem is? Here's the demo url: Demo Url

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• Suppressing PostSharp Multicast with Attribute

  - by Dan Bryant

  I've recently started experimenting with PostSharp and I found a particularly helpful aspect to automate implementation of INotifyPropertyChanged. You can see the example here. The basic functionality is excellent (all properties will be notified), but there are cases where I might want to suppress notification. For instance, I might know that a particular property is set once in the constructor and will never change again. As such, there is no need to emit the code for NotifyPropertyChanged. The overhead is minimal when classes are not frequently instantiated and I can prevent the problem by switching from an automatically generated property to a field-backed property and writing to the field. However, as I'm learning this new tool, it would be helpful to know if there is a way to tag a property with an attribute to suppress the code generation. I'd like to be able to do something like this: [NotifyPropertyChanged] public class MyClass { public double SomeValue { get; set; } public double ModifiedValue { get; private set; } [SuppressNotify] public double OnlySetOnce { get; private set; } public MyClass() { OnlySetOnce = 1.0; } }

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• WPF View/ViewModels using Generics- how?

  - by Investor5555

  New to WPF, so please bear with me... Suppose I have 2 tables in SQL Thing OtherThing Both have the exact same fields: ID (int) Name (string) Description (string) IsActive (bit/bool) DateModified (DateTime) So, I want to create one Model (not two) and do something like this: BaseModel<T>() { public int ID {get;set;} ... } etc. (of course, using the INotifyPropertyChanged, just trying to keep the code simple). I want to be able to create a BaseView and BaseViewModel that would work with whatever model conforms to the Thing/OtherThing. I am really at a loss as to what to do here to make this generic, so I don't have to have a ThingView/ThingViewModel and a OtherThingView/OtherThingViewModel... It seems that this should be simple, but I cannot seem to figure it out. Does anyone have a code example where they could interchange various items from a dropdown list using one view, one ViewModel, and one base datamodel (and switching out the type from a dropdown)? For example, a combobox has 3 identical table structures for Thing OtherThing SomeThing and on selection changed, I want to pull the data from whatever table was selected, to be able to do standard CRUD operations on any of these 3 tables, without having to create concrete classes for each view/viewmodel.

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• Data Flow Object Graph and An Execution Engine for it

  - by M Dotnet

  I would like to build a custom workflow engine from scratch. The input to this workflow is a data flow diagram which is composed of a series of activities connected together through lines where each each represent the data flow. Each activity can export multiple outputs. Activities are complex math functions but the logic is hidden from the user. My workflow engine job is to execute the given data flow diagram. Each activity within the data flow diagram is a custom activity and each activity can output different outputs. How do you suggest to model the data flow diagram object? I need to be able to construct the data flow diagram problematically (no need for drag and drop) but I need to display the final result graphically (for display and debugging purposes). Are there any libraries out there that I could use? Should I keep the workflow presentable as an xml? I know that there are many projects out there trying to essentially doing similar thing by building such workflow engines but I need something light weight and open source. I do not need any state machine execution engine and mine is primarily sequential workflow with fork and join capabilities. My activities are wrappable as basic C# classes and I do NOT want to use anything as heavy as .NET workflow foundation.

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• .net real time stream processing - needed huge and fast RAM buffer

  - by mack369

  The application I'm developing communicates with an digital audio device, which is capable of sending 24 different voice streams at the same time. The device is connected via USB, using FTDI device (serial port emulator) and D2XX Drivers (basic COM driver is to slow to handle transfer of 4.5Mbit). Basically the application consist of 3 threads: Main thread - GUI, control, ect. Bus reader - in this thread data is continuously read from the device and saved to a file buffer (there is no logic in this thread) Data interpreter - this thread reads the data from file buffer, converts to samples, does simple sample processing and saves the samples to separate wav files. The reason why I used file buffer is that I wanted to be sure that I won't loose any samples. The application doesn't use recording all the time, so I've chosen this solution because it was safe. The application works fine, except that buffered wave file generator is pretty slow. For 24 parallel records of 1 minute, it takes about 4 minutes to complete the recording. I'm pretty sure that eliminating the use of hard drive in this process will increase the speed much. The second problem is that the file buffer is really heavy for long records and I can't clean this up until the end of data processing (it would slow down the process even more). For RAM buffer I need at lest 1GB to make it work properly. What is the best way to allocate such a big amount of memory in .NET? I'm going to use this memory in 2 threads so a fast synchronization mechanism needed. I'm thinking about a cycle buffer: one big array, the Bus Reader saves the data, the Data Interpreter reads it. What do you think about it? [edit] Now for buffering I'm using classes BinaryReader and BinaryWriter based on a file.

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• problem with running Servlet on Tomcat: InvocationTargetException

  - by Fahim

  Hi, I am new to Tomcat, and trying to run a simple HelloWorld servlet. I have installed Tomcat 6, and Jdk1.6 on Mandriva Linux, set CLASSPATH and JAVA_HOME. I have the following files and directories: $CATALINA_HOME/webapps/MyApp/WEB_INF/classes/TestServlet.class $CATALINA_HOME/webapps/MyApp/WEB_INF/web.xml My web.xml file contains the following: http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5" <description>ZibJana Localization</description> <display-name>ZibJana Localization</display-name> <!-- Define the servlets for this application--> <servlet> <servlet-name>ZibJana</servlet-name> <servlet-class>TestServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>ZibJana</servlet-name> <url-pattern>*</url-pattern> </servlet-mapping> But when I try to invoke my servlet with url http://localhost:8080/MyApp, tomcat fails to launch launch the servlet. I checked in the $CATALINA_HOME/logs/catalina.out log-file and found the following error, which occurs every time I start tomcat service. INFO: Deploying web application directory MyApp 16-Mar-2010 12:05:38 AM org.apache.tomcat.util.digester.Digester endElement SEVERE: End event threw exception java.lang.reflect.InvocationTargetException at sun.reflect.GeneratedMethodAccessor18.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) Please let me know where my mistake is. Thanks in advance.

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• VB.NET switching from ADO.NET to LINQ

  - by Cj Anderson

  I'm VERY new to Linq. I have an application I wrote that is in VB.NET 2.0. Works great, but I'd like to switch this application to Linq. I use ADO.NET to load XML into a datatable. The XML file has about 90,000 records in it. I then use the Datatable.Select to perform searches against that Datatable. The search control is a free form textbox. So if the user types in terms it searches instantly. Any further terms that are typed in continue to restrict the results. So you can type in Bob, or type in Bob Barker. Or type in Bob Barker Price is Right. The more criteria typed in the more narrowed your result. I bind the results to a gridview. Moving forward what all do I need to do? From a high level, I assume I need to: 1) Go to Project Properties -- Advanced Compiler Settings and change the Target framework to 3.5 from 2.0. 2) Add the reference to System.XML.Linq, Add the Imports statement to the classes. So I'm not sure what the best approach is going forward after that. I assume I use XDocument.Load, then my search subroutine runs against the XDocument. Do I just do the standard Linq query for this sort of repeated search? Like so: var people = from phonebook in doc.Root.Elements("phonebook") where phonebook.Element("userid") = "whatever" select phonebook; Any tips on how to best implement?

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• Help with Struts Action mapping

  - by nicotine

  I am having a problem with my struts application it is a class enrollment app and when the user clicks on a "show enrolled courses" button it is supposed to show the courses they are enrolled in but it shows nothing at the moment. Struts/Apache does not return any errors, it Just shows a blank page and I cannot figure out why. My action mapping in my struts-config: <action path="/showEnrolled" type="actions.ShowEnrolledAction" name="UserFormEnrolled" scope="request" validate="true" input="/students/StudentMenu.jsp"> <forward name="success" path="/students/enrolled.jsp"/> </action> My link to the jsp enrolled.jsp page: <li><html:form action="/showEnrolled"> <html:hidden property="id" value= "<%=request.getRemoteUser()%>"/> <html:submit value = "View Enrolled Classes"/> </html:form> </li> When I click the link I get nothing but my menu on the page. The text headings for the page are not even displayed.

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• C++ : Avoid lot of boolean variable for multiple verification conditions in trading app

  - by Naveen

  Hi i am a junior dev in trading app... we have a order refresh verification unit. It has to verify order confirmation from exchange. We send a bunch of different request in bulk ( NEW, MODIFY, CANCEL ) to exchange... Verification has to happen for max N times with each T intervals for all orders. if verification successful for all the order before N retry then fine.. otherwise we need to indicate as verification unsuccessfull. i hv done a basic coding done in very urgent like below for( N times ) { for_each ( sent_request_order ) // SENT { 1) get all the refreshed order from DB or shared mem i.e REFRESHED 2) find current sent order in REFRESHED if( not_found ) not refreshed from exchange, continue to next order if( found ) case NEW : //check for new status, mark verification done case MODIFY : //check for modified status.. //if not mark pending, go to next order, //revisit the same after T time case CANCEL : //check for cancelled status.. //if not mark pending, go to next order, //revisit the same after T time } if( all_verified ) exit from verification. wait ( T sec ) } order_verification_pending, order_verification_done, order_visited, order_not_visited, all_verified, all_not_verified ... lot of boolean flags used for indication.. is there any better approach for doing this.... splitting responsibilities across the classes......???? i know this is not a general question.... but still flags are making me tidious to handle...

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• Maven build fails on an Ant FTP task failure

  - by fraido

  I'm using the FTP Ant task with maven-antrun-plugin <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-antrun-plugin</artifactId> <executions> <execution> <id>ftp</id> <phase>generate-resources</phase> <configuration> <tasks> <ftp action="get" server="${ftp.server.ip}" userid="${ftp.server.userid}" password="${ftp.server.password}" remotedir="${ftp.server.remotedir}" depends="yes" verbose="yes" skipFailedTransfers="true" ignoreNoncriticalErrors="true"> <fileset dir="target/test-classes/testdata"> <include name="**/*.html" /> </fileset> </ftp> </tasks> </configuration> <goals> <goal>run</goal> </goals> </execution> </executions> ... the problem is that my build fails when the folder ${ftp.server.remotedir} doesn't exist. I tried to specify skipFailedTransfers="true" ignoreNoncriticalErrors="true but these don't fix the problem and the build keeps failing. An Ant BuildException has occured: could not change remote directory: 550 /myBadDir: The system cannot find the file specified. Do you know how to instruct my maven build to don't care about this Ant task error

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• FIFO dequeueing in python?

  - by Aaron Ramsey

  hello again everybody— I'm looking to make a functional (not necessarily optimally efficient, as I'm very new to programming) FIFO queue, and am having trouble with my dequeueing. My code looks like this: class QueueNode: def __init__(self, data): self.data = data self.next = None def __str__(self): return str(self.data) class Queue: def__init__(self): self.front = None self.rear = None self.size = 0 def enqueue(self, item) newnode = QueueNode(item) newnode.next = None if self.size == 0: self.front = self.rear = newnode else: self.rear = newnode self.rear.next = newnode.next self.size = self.size+1 def dequeue(self) dequeued = self.front.data del self.front self.size = self.size-1 if self.size == 0: self.rear = None print self.front #for testing if I do this, and dequeue an item, I get the error "AttributeError: Queue instance has no attribute 'front'." I guess my function doesn't properly assign the new front of the queue? I'm not sure how to fix it though. I don't really want to start from scratch, so if there's a tweak to my code that would work, I'd prefer that—I'm not trying to minimize runtime so much as just get a feel for classes and things of that nature. Thanks in advance for any help, you guys are the best.

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• Can not find Driver when using generic database bundle

  - by Marc

  I have a project that is build up from several OSGi bundles. One of them is a generic Database bundle that defines a DataSource that can be used throughout the project. The spring bean definition of this service is: <osgi:service interface="javax.sql.DataSource"> <bean class="org.postgresql.ds.PGPoolingDataSource"> <property name="databaseName" value="xxx" /> <property name="serverName" value="xxx" /> <property name="user" value="xxx" /> <property name="password" value="xxx" /> </bean> </osgi:service> Now, when using this DataSource is a different bundle, we get an error: No suitable driver found for jdbc:postgresql://localhost/xxx I have tried the following to add the org.postgresql.Driver to the DriverManager: Instantiated an empty bean for that Driver in the spring context, like this: <bean class="org.postgresql.Driver" /> Instantiated the Driver statically in one of the classes, like this: Class.forName("org.postgresql.Driver"); Added a file META-INF\services\java.sql.Driver with the content org.postgresql.Driver None of these solutions seems to help.

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• Should a new language compiler target the JVM?

  - by Pindatjuh

  I'm developing a new language. My initial target was to compile to native x86 for the Windows platform, but now I am in doubt. I've seen some new languages target the JVM (most notable Scala and Clojure). Ofcourse it's not possible to port every language easily to the JVM; to do so, it may lead to small changes to the language and it's design. So that's the reason behind this doubt, and thus this question: Is targetting the JVM a good idea, when creating a compiler for a new language? Or should I stick with x86? I have experience in generating JVM bytecode. Are there any workarounds to JVM's GC? The language has deterministic implicit memory management. How to produce JIT-compatible bytecode, such that it will get the highest speedup? Is it similar to compiling for IA-32, such as the 4-1-1 muops pattern on Pentium? I can imagine some advantages (please correct me if I'm wrong): JVM bytecode is easier than x86. Like x86 communicates with Windows, JVM communicates with the Java Foundation Classes. To provide I/O, Threading, GUI, etc. Implementing "lightweight"-threads.I've seen a very clever implementation of this at http://www.malhar.net/sriram/kilim/. Most advantages of the Java Runtime (portability, etc.) The disadvantages, as I imagined, are: Less freedom? On x86 it'll be more easy to create low-level constructs, while JVM has a higher level (more abstract) processor. Most disadvantages of the Java Runtime (no native dynamic typing, etc.)

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• Should a setter return immediately if assigned the same value?

  - by Andrei Rinea

  In classes that implement INotifyPropertyChanged I often see this pattern : public string FirstName { get { return _customer.FirstName; } set { if (value == _customer.FirstName) return; _customer.FirstName = value; base.OnPropertyChanged("FirstName"); } } Precisely the lines if (value == _customer.FirstName) return; are bothering me. I've often did this but I am not that sure it's needed nor good. After all if a caller assigns the very same value I don't want to reassign the field and, especially, notify my subscribers that the property has changed when, semantically it didn't. Except saving some CPU/RAM/etc by freeing the UI from updating something that will probably look the same on the screen/whatever_medium what do we obtain? Could some people force a refresh by reassigning the same value on a property (NOT THAT THIS WOULD BE A GOOD PRACTICE HOWEVER)? 1. Should we do it or shouldn't we? 2. Why?

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• Best way to get a single value from a DataTable?

  - by PiersMyers

  I have a number of static classes that contain tables like this: using System; using System.Data; using System.Globalization; public static class TableFoo { private static readonly DataTable ItemTable; static TableFoo() { ItemTable = new DataTable("TableFoo") { Locale = CultureInfo.InvariantCulture }; ItemTable.Columns.Add("Id", typeof(int)); ItemTable.Columns["Id"].Unique = true; ItemTable.Columns.Add("Description", typeof(string)); ItemTable.Columns.Add("Data1", typeof(int)); ItemTable.Columns.Add("Data2", typeof(double)); ItemTable.Rows.Add(0, "Item 1", 1, 1.0); ItemTable.Rows.Add(1, "Item 2", 1, 1.0); ItemTable.Rows.Add(2, "Item 3", 2, 0.75); ItemTable.Rows.Add(3, "Item 4", 4, 0.25); ItemTable.Rows.Add(4, "Item 5", 1, 1.0); } public static DataTable GetItemTable() { return ItemTable; } public static int Data1(int id) { DataRow[] dr = ItemTable.Select("Id = " + id); if (dr.Length == 0) { throw new ArgumentOutOfRangeException("id", "Out of range."); } return (int)dr[0]["Data1"]; } public static double Data2(int id) { DataRow[] dr = ItemTable.Select("Id = " + id); if (dr.Length == 0) { throw new ArgumentOutOfRangeException("id", "Out of range."); } return (double)dr[0]["Data2"]; } } Is there a better way of writing the Data1 or Data2 methods that return a single value from a single row that matches the given id?

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