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• Problem creating XML using c#

  - by Pankaj

  I am searching a batter solution for creating xml through xml serialization. What i need, i have a given format like this <product Id="1"> <name>2 1/2 X 6 PVC NIPPLE TOE SCH 80</name> <notes> <note>!--note 1---</note> <note>!--note 2--</note> ...... </notes> </product> what i am doing here, i created a 2 classes like this public class product { [XmlElement("name")] public string Name { get; set; } [XmlArray("notes")] public List<notes> ListNotes { get; set; } } public class notes { [XmlIgnore] public string Note { get; set; } } when i am serializing this then i am getting xml in this formate <product Id="1"> <name>2 1/2 X 6 PVC NIPPLE TOE SCH 80</name> <notes> <notes> <note>!--note 1---</note> <note>!--note 2--</note> </notes> </notes> </product> i don't want extra <notes>. Any batter solution to solve this problem? Thanks

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• Basic PHP OOPS Query

  - by appu

  Ok. I am starting out OOPS in PHP. Created a couple of classes: customer(parent) and sales(child) class that inherits from parent class. Created another testcustomer.php in which a new sales object is created however the salesprint() function defined in the sales class does not echo out customer's name though it is set to be "Jane" in the class.customer.php(parent). My thinking is that when sales class extends customer class PHP automatically includes all the code from class.customer.php to sales.customer.php and therefore the constructor in parent class set $name to "Jane". Here is the code: class.customer.php <?php class customer{ private $name; private $cust_no; public function __construct($customerid) { $this->name = 'Jane'; $this->cust_no = $customerid; } } ?> class.sales.php <?php require_once('class.customer.php'); class sales extends customer{ public function salesprint($customerid) { echo "Hello $this->name this is a print of your purchased products"; } } ?> testcustomer.php require_once('class.sales.php'); $objsales = new sales(17); $objsales->salesprint(17); ?> The Output I get Hello this is a print of your purchased products. What am i doing wrong ? thanks romesh

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• What makes an effective UI for displaying versioning of structured hierarchical data

  - by Fadrian Sudaman

  Traditional version control system are displaying versioning information by grouping Projects-Folders-Files with Tree view on the left and details view on the right, then you will click on each item to look at revision history for that configuration history. Assuming that I have all the historical versioning information available for a project from Object-oriented model perspective (e.g. classes - methods - parameters and etc), what do you think will be the most effective way to present such information in UI so that you can easily navigate and access the snapshot view of the project and also the historical versioning information? Put yourself in the position that you are using a tool like this everyday in your job like you are currently using SVN, SS, Perforce or any VCS system, what will contribute to the usability, productivity and effectiveness of the tool. I personally find the classical way for display folders and files like above are very restrictive and less effective for displaying deep nested logical models. Assuming that this is a greenfield project and not restricted by specific technology, how do you think I should best approach this? I am looking for idea and input here to add values to my research project. Feel free to make any suggestions that you think is valuable. Thanks again for anyone that shares their thoughts.

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• Best way to create a SPARQL endpoint for a RDBMS (MySQL database)

  - by Ankur

  I am doing (want to do) some experiments with Linked Open Datasets particularly those put out by governments. I have a RDBMS (more specifically MySQL). I designed it with semantic web ideas in mind i.e. I have a information stored as objects, predicates and classes which define objects. In turn all objects are related to each other though statements of the form subject -- predicate -- object (where the subjects are from the objects table). I want to be able to query other RDF triple stores from my application and let other triple stores query my data. Is it possible to "set something up" so that this is possible? I have looked at Jena. Using Jena seems to mean I have to it as a storage application rather than MySQL - the only problem with this is that I include a new concept called a category (which I don't think is part of the semantic web languages). I will use categories to help with displaying information (they don't have any other meaning) but using Jena seems to mean that I can't organise predicates under categories for more convenient viewing. I am using Java so a JAVA API is preferred. It's also possible I misunderstood the purpose of Jena, and maybe that can be of use, but I am not sure how. I am sure four days from now this question will seem rather silly, but at the moment I am somewhat confused about how to proceed.

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• Extracting function declarations from a PHP file

  - by byronh

  I'm looking to create an on-site API reference for my framework and application. Basically, say I have a class file model.class.php: class Model extends Object { ... code here ... // Separates results into pages. // Returns Paginator object. final public function paginate($perpage = 10) { ... more code here ... } } and I want to be able to generate a reference that my developers can refer to quickly in order to know which functions are available to be called. They only need to see the comments directly above each function and the declaration line. Something like this (similar to a C++ header file): // Separates results into pages. // Returns Paginator object. final public function paginate($perpage = 10); I've done some research and this answer looked pretty good (using Reflection classes), however, I'm not sure how I can keep the comments in. Any ideas? EDIT: Sorry, but I want to keep the current comment formatting. Myself and the people who are working on the code hate the verbosity associated with PHPDocumentor. Not to mention a comment-rewrite of the entire project would take years, so I want to preserve just the // comments in plaintext.

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• Desktop-like UI implementations for Java web applications?

  - by localshred

  At work we're discussing upgrading our view layer for our web application. We're currently running an old and "modified" version of FreeMarker Classic, which is a pain to work with. One of our developers suggested using a Component UI style architecture similar to desktop style environments. Essentially, this would mean that you would build custom HTML components as Java Classes that the controller would render into the Document view. This would completely take away the need to write HTML into a view layer. The Components would generate the view layer for you. For instance, the following rendered HTML: <h1>I am a title</h1> <p>I am a paragraph.</p> Would be generated by doing something like: String titleString = "I am a title"; html.elements.Heading heading = new html.elements.Heading(Heading.H1, titleString); String paraString = "I am a paragraph."; html.elements.Paragraph paragraph = new html.elements.Paragraph(paraString); PrintWriter somePrintWriter = new PrintWriter(); Document document = new Document(); document.addElement(heading); document.addElement(paragraph); document.compose(somePrintWriter); The above code is just an example, don't critique the names or style, I just wrote it for a quick demonstration of what we may be trying to accomplish. I'm trying to determine if this has been done before in Java, and if so if there are any links I can be pointed to. I've been researching it as much as I can, but haven't found any implementations that completely remove the template layer (such as JSP or JSF). Thanks!

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• Creating a complex tree model in Qt

  - by Zeke

  I'm writing an IRC Client (yes another one). Long story short. I'm writing a Server dialogue that keeps a list of this: Identity Networks Channels Addresses I have 3 different list views that will be for the Networks, Channels and Addresses. When the user changes the Identity (combo box). The network listview will lookup all the networks for that specific Identity. After it loads up the Networks it will automatically select the first network and then load all the channels and addresses for that specific network. The problem is I want to have 3 views for 1 model, to minimise all the memory and the loading of data. So that it makes it much easier to manage and not do a bunch of work. If you'd look at QColumnView it's the same exact thing. But I don't need it to be on one exact page since the views are on entirely different tabs to make it easier to go through the Server dialogue. I'm wondering what will be the best way to go about handling this complexity. The information is stored in a SQLite database. I already have the classes written to extract and store it. Just the modelling is the painful part of this solution.

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• Spawning a thread in python

  - by morpheous

  I have a series of 'tasks' that I would like to run in separate threads. The tasks are to be performed by separate modules. Each containing the business logic for processing their tasks. Given a tuple of tasks, I would like to be able to spawn a new thread for each module as follows. from foobar import alice, bob charles data = getWorkData() # these are enums (which I just found Python doesn't support natively) :( tasks = (alice, bob, charles) for task in tasks # Ok, just found out Python doesn't have a switch - @#$%! # yet another thing I'll need help with then ... switch case alice: #spawn thread here - how ? alice.spawnWorker(data) No prizes for guessing I am still thinking in C++. How can I write this in a Pythonic way using Pythonic 'enums' and 'switch'es, and be able to run a module in a new thread. Obviously, the modules will all have a class that is derived from a ABC (abstract base class) called Plugin. The spawnWorker() method will be declared on the Plugin interface and defined in the classes implemented in the various modules. Maybe, there is a better (i.e. Pythonic) way of doing all this?. I'd be interested in knowing

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• Static Variables somehow maintaining state?

  - by gfoley

  I am working on an existing project, setup by another coder. I'm having some trouble understanding how state is being maintained between pages. There is a Class library which has some helper objects. Mostly these objects are just used for there static methods and rarely instantiated or inherited. This is an example class I'm testing with. public sealed class Application { public static string Test; } Now when i run something like the following in the base class of my page, I would expect the result to be "1: 2:Test" all the time (note that "1" is empty), but strangly its only this way the first time it is run. Then every time afterwards its "1:Test 2:Test". Somehow its maintaining the state of the static variable between pages and being refreshed?? Response.Write("1:" + SharedLibrary.Application.Test); SharedLibrary.Application.Test = "Test"; Response.Write(" 2:" + SharedLibrary.Application.Test); I need to create more classes like this, but want to understand why this is occurring in the first place. Many Thanks

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• Adventures on Enterprise Library 5.0: Who moved my cheese (namespace)

  - by Junior Mayhé

  Jesus, Krishna, Budda! I've migrated to EntLib 5.0, but classes like ISymmetricCryptoProvider are not recognized anymore. Funny to say that Data, Logging and other blocks are working compiling fine. Here's the problematic class: using System; using System.Collections.Generic; using System.Text; using Microsoft.Practices.EnterpriseLibrary.Common.Configuration;//-->it's not working anymore using Microsoft.Practices.EnterpriseLibrary.Security.Cryptography;//-->it's not working anymore namespace MyClassLibrary.Security.EnterpriseLibrary { public sealed class Crypto { public static ISymmetricCryptoProvider MyProvider { get { //IConfigurationSource is not recognized either, neither SystemConfigurationSource IConfigurationSource cs = new SystemConfigurationSource(); SymmetricCryptoProviderFactory scpf = new SymmetricCryptoProviderFactory(cs); ISymmetricCryptoProvider p = scpf.CreateDefault(); return p; } } The references are fine on project too. I really don't know why this particular project it's causing too many trouble on VS2010! Older references were deleted, project was cleaned, rebuilt, but can't make it compile :-( The references are: Microsoft.Practices.EnterpriseLibrary.Common Microsoft.Practices.EnterpriseLibrary.Logging Microsoft.Practices.EnterpriseLibrary.Logging.Database Microsoft.Practices.EnterpriseLibrary.Security Microsoft.Practices.EnterpriseLibrary.Security.Cryptography Why some namespaces can be found while others can't?

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• How can I get type information at runtime from a DMP file in a Windbg extension?

  - by pj4533

  This is related to my previous question, regarding pulling objects from a dmp file. As I mentioned in the previous question, I can successfully pull object out of the dmp file by creating wrapper 'remote' objects. I have implemented several of these so far, and it seems to be working well. However I have run into a snag. In one case, a pointer is stored in a class, say of type 'SomeBaseClass', but that object is actually of the type 'SomeDerivedClass' which derives from 'SomeBaseClass'. For example it would be something like this: MyApplication!SomeObject +0x000 field1 : Ptr32 SomeBaseClass +0x004 field2 : Ptr32 SomeOtherClass +0x008 field3 : Ptr32 SomeOtherClass I need someway to find out what the ACTUAL type of 'field1' is. To be more specific, using example addresses: MyApplication!SomeObject +0x000 field1 : 0cae2e24 SomeBaseClass +0x004 field2 : 0x262c8d3c SomeOtherClass +0x008 field3 : 0x262c8d3c SomeOtherClass 0:000> dt SomeBaseClass 0cae2e24 MyApplication!SomeBaseClass +0x000 __VFN_table : 0x02de89e4 +0x038 basefield1 : (null) +0x03c basefield2 : 3 0:000> dt SomeDerivedClass 0cae2e24 MyApplication!SomeDerivedClass +0x000 __VFN_table : 0x02de89e4 +0x038 basefield1 : (null) +0x03c basefield2 : 3 +0x040 derivedfield1 : 357 +0x044 derivedfield2 : timecode_t When I am in WinDbg, I can do this: dt 0x02de89e4 And it will show the type: 0:000> dt 0x02de89e4 SomeDerivedClass::`vftable' Symbol not found. But how do get that inside an extension? Can I use SearchMemory() to look for 'SomeDerivedClass::`vftable'? If you follow my other question, I need this type information so I know what type of wrapper remote classes to create. I figure it might end up being some sort of case-statement, where I have to match a string to a type? I am ok with that, but I still don't know where I can get that string that represents the type of the object in question (ie SomeObject-field1 in the above example).

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• Servlet doPost() Method setup?

  - by Mark R

  I am interested in creating a web app that uses JSP, Servlets and XML. At the moment I have the following: JSP - Form input. Servlet - Retrieving Form data and sending that data to a java object. Java object (1) - Converts data into XML file....instantiates java object (2). Java object (2) - Sends that file to a database. On the returning side the database will send back another XML file that I will then process using XSLT to display back to the user. Can I place that XSLT code in the orignial Servlets doPost() method? So my doPost()` method would: Retrieve user inputted data from the form on my JSP page. Instantiate a java object to convert that data to XML, in-turn that object will instantiates another object to send the XML file to a database. Converts the resulting XML file sent from the database and displays it for the user. Can one servlet doPost() method handle all of this? If not, how would I set up my application and classes to handle this work flow? Thank you in advance

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• Searching in an Arraylist

  - by Puchatek

  Currently I have two classes. A Classroom class and a School class. I would like to write a method in the School class public void showClassRoomDetails which would find the classroom details by only using the teacherName. e.g. teacherName = Daniel className = Science teacherName = Bob className = Maths so when I input Bob, it would print out Bob and Maths many, thanks public class Classroom { private String classRoomName; private String teacherName; public void setClassRoomName(String newClassRoomName) { classRoomName = newClassRoomName; } public String returnClassRoomName() { return classRoomName; } public void setTeacherName(String newTeacherName) { teacherName = newTeacherName; } public String returnTeacherName() { return teacherName; } } import java.util.ArrayList; public class School { private ArrayList<Classroom> classrooms; private String classRoomName; private String teacherName; public School() { classrooms = new ArrayList<Classroom>(); } public void addClassRoom(Classroom newClassRoom, String theClassRoomName) { classrooms.add(newClassRoom); classRoomName = theClassRoomName; } public void addTeacherToClassRoom(int classroomId, String TeacherName) { if (classroomId < classrooms.size() ) { classrooms.get(classroomId).setTeacherName(TeacherName); } } public void showClassRoomDetails { //loop System.out.println(returnClassRoomName); System.out.println(returnTeacherName); } }

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• How do I add code automatically to a derived function in C++

  - by Ian

  I have code that's meant to manage operations on both a networked client and a server, since there is significant overlap between the two. However, there are a few functions here and there that are meant to be exclusively called by the client or server, and accidentally calling a client function on the server (or vice versa) is a significant source of bugs. To reduce these sorts of programming errors, I'm trying to tag functions so that they'll raise a ruckus if they're misused. My current solution is a simple macro at the start of each function that calls an assert if the client or server accesses members they shouldn't. However, this runs into problems when there are multiple derived instances of classes, in that I have to tag the implementation as client or server side in EVERY child class. What I'd like to be able to do is put a tag in the virtual member's signature in the base class, so that I only have to tag it once and not run into errors by forgetting to do it repeatedly. I've considered putting a check in a base class implementation and then referring to it with something like base::functionName, but that runs into the same issue as far as needing to manually add the function call to every implementation. Ideally, I'd be able to have parent versions of the function called automatically like default constructors do. Does anybody know how to achieve something like this in C++? Is there an alternate approach I should be considering? Thanks!

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• Hibernate saveorUpdate method problem

  - by umesh awasthi

  Hi all, i am trying to work on with Hibernate (Database side for first time) and some how struck in choosing best possible way to use saveOrUpdate or Save.Update i have a destination POJO class and its other attributes which needs to be updated along with the Destination entity. i am getting an XML file to be imported and i am using the following code to update/save the destination entity along with its attribute classes. try{ getSessionFactory().getCurrentSession().beginTransaction(); getSessionFactory().getCurrentSession().saveOrUpdate(entity); getSessionFactory().getCurrentSession().getTransaction().commit(); } catch(Exception e){ getSessionFactory().getCurrentSession().getTransaction().rollback(); } finally{ getSessionFactory().close(); } everything is working fine untill i am using the same session instance.but later on when i am using the same XML file to update the destination PO for certain attributes it giving me the following error. SEVERE: Duplicate entry 'MNLI' for key 'DESTINATIONID' 9 Jan, 2011 4:58:11 PM org.hibernate.event.def.AbstractFlushingEventListener performExecutions SEVERE: Could not synchronize database state with session org.hibernate.exception.ConstraintViolationException: Could not execute JDBC batch update at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:94) at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66) at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:275) at org.hibernate.jdbc.AbstractBatcher.prepareStatement(AbstractBatcher.java:114) at org.hibernate.jdbc.AbstractBatcher.prepareStatement(AbstractBatcher.java:109) at org.hibernate.jdbc.AbstractBatcher.prepareBatchStatement(AbstractBatcher.java:244) at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2242) at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2678) at org.hibernate.action.EntityInsertAction.execute(EntityInsertAction.java:79) i am using UUID as primary key for the Destination table and in destination table i have a destination id which is unique.but i can understand that in the secodn case hibernate is not able to find if there is already an entry for the same destination in the DB and trying to execute insert statement rather than update. one possible solution is i can user destinationid to check if there is already a destination inplace with the given id and based on the results i can issue save or update command. my question is can this be achieve by any other good way..? Thanks in advance

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• Foreign key relationships in Entity Framework

  - by Anders Svensson

  I'm trying to add an object created from Entity Data Model classes. I have a table called Users, which has turned into a User EDM class. And I also have a table Pages, which has become a Page EDM class. These tables have a foreign key relationship, so that each page is associated with many users. Now I want to be able to add a page, but I can't get how to do it. I get a nullreference exception on Users below. I'm still rather confused by all this, so I'm sure it's a simple error, but I just can't see how to do it. Also, by the way, the compiler requires that I set PageID in the object initializer, even though this field is set to be an automatic id in the table. Am I doing it right just setting it to 0, expecting it to be updated automatically in the table when saved, or how should I do that? Any help appreciated! The method in question: private Page GetPage(User currentUser) { string url = _request.ServerVariables["url"].ToLower(); var userPages = from p in _context.PageSet where p.Users.UserID == currentUser.UserID select p; var existingPage = userPages.FirstOrDefault(e => e.Url == url); //Could be combined with above, but hard to read? if (existingPage != null) return existingPage; Page page = new Page() { Count = 0, Url = _request.ServerVariables["url"].ToLower(), PageID = 0, //Only initial value, changed later? }; _context.AddToPageSet(page); page.Users.UserID = currentUser.UserID; //Here's the problem... return page; }

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• How do I build a filtered_streambuf based on basic_streambuf?

  - by swestrup

  I have a project that requires me to insert a filter into a stream so that outgoing data will be modified according to the filter. After some research, it seems that what I want to do is create a filtered_streambuf like this: template <class StreamBuf class filtered_streambuf: public StreamBuf { ... } And then insert a filtered_streambuf<> into whichever stream I need to be filtered. My problem is that I don't know what invariants I need to maintain while filtering a stream, in order to ensure that Derived classes can work as expected. In particular, I may find I have filtered_streambufs built over other filtered_streambufs. All the various stream inserters, extractors and manipulators work as expected. The trouble is that I just can't seem to work out what the minimal interface is that I need to supply in order to guarantee that an iostream will have what it needs to work correctly. In particular, do I need to fake the movement of the protected pointer variables, or not? Do I need a fake data buffer, or not? Can I just override the public functions, rewriting them in terms of the base streambuf, or is that too simplistic?

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• tomcat resource missing, servlet not running

  - by user2837260

  import javax.servlet.*; import java.io.*; public class MyServlet implements Servlet { public void init(ServletConfig con) {} public void service(ServletRequest req, ServletResponse res) throws IOException,ServletException { res.setContentType("text/html"); PrintWriter out=res.getWriter(); String s="blah"; String s1="blah"; out.println("<html><body>"); if((s.equals(req.getParameter("firstname")))&&(s1.equals(req.getParameter("pwd")))) out.println("passwords match"); else out.println("password and name combo does not match"); out.println("</body></html>"); } public void destroy() {} public ServletConfig getServletConfig() { return null;} public String getServletInfo() { return null;} } this is my java file with the servlet class.its saved with the name MyServlet.java and so is the class file. and here is the xml file: <web-app> <servlet> <servlet-name>demoo</servlet-name> <servlet-class>MyServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>demoo</servlet-name> <url-pattern>/demo</url-pattern> </servlet-mapping> </web-app> i have made the folder as WEB-INF and then classes... WEB-INF also contains the .xml file but when i try to run the servlet , it says resource not found ps- i am already looking for the servlet with the name :demo localhost:8081/s1/demo* s1 is the war file * a html file in the war file seems to run fine on the server though. *

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• Can ScalaCheck/Specs warnings safely be ignored when using SBT with ScalaTest?

  - by pdbartlett

  I have a simple FunSuite-based ScalaTest: package pdbartlett.hello_sbt import org.scalatest.FunSuite class SanityTest extends FunSuite { test("a simple test") { assert(true) } test("a very slightly more complicated test - purposely fails") { assert(42 === (6 * 9)) } } Which I'm running with the following SBT project config: import sbt._ class HelloSbtProject(info: ProjectInfo) extends DefaultProject(info) { // Dummy action, just to show config working OK. lazy val solveQ = task { println("42"); None } // Managed dependencies val scalatest = "org.scalatest" % "scalatest" % "1.0" % "test" } However, when I runsbt test I get the following warnings: ... [info] == test-compile == [info] Source analysis: 0 new/modified, 0 indirectly invalidated, 0 removed. [info] Compiling test sources... [info] Nothing to compile. [warn] Could not load superclass 'org.scalacheck.Properties' : java.lang.ClassNotFoundException: org.scalacheck.Properties [warn] Could not load superclass 'org.specs.Specification' : java.lang.ClassNotFoundException: org.specs.Specification [warn] Could not load superclass 'org.specs.Specification' : java.lang.ClassNotFoundException: org.specs.Specification [info] Post-analysis: 3 classes. [info] == test-compile == For the moment I'm assuming these are just "noise" (caused by the unified test interface?) and that I can safely ignore them. But it is slightly annoying to some inner OCD part of me (though not so annoying that I'm prepared to add dependencies for the other frameworks). Is this a correct assumption, or are there subtle errors in my test/config code? If it is safe to ignore, is there any other way to suppress these errors, or do people routinely include all three frameworks so they can pick and choose the best approach for different tests? TIA, Paul. (ADDED: scala v2.7.7 and sbt v0.7.4)

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• Structuring the UI code of a single-page EXTjs Web app using Rails?

  - by Daniel Beardsley

  I’m in the process of creating a large single-page web-app using ext-js for the UI components with Rails on the backend. I’ve come to good solutions for transferring data using Whorm gem and Rails support of RESTful Resources. What I haven’t come to a conclusion on is how to structure the UI and business logic aspects of the application. I’ve had a look at a few options, including Netzke but haven’t seen anything that I really think fits my needs. How should a web-application that uses ext-js components, layouts, and controls in the browser and Rails on the server best implement UI component re-use, good organization, and maintainability while maintaining a flexible layout design. Specifically I’m looking for best-practice suggestions for structuring the code that creates and configures UI components (many UI config options will be based on user data) Should EXT classes be extended in static JS for often re-used customizations and then instantiated with various configuration options by generated JS within html partials? Should partials create javascript blocks that instantiate EXT components? Should partials call helpers that return ruby hashes for EXT component config which is then dumped to Json? Something else entirely? There are many options and I'd love to hear from people who've been down this road and found some methodology that worked for them.

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• What is wrong with locking non-static fields? What is the correct way to lock a particular instance?

  - by smartcaveman

  Why is it considered bad practice to lock non-static fields? And, if I am not locking non-static fields, then how do I lock an instance method without locking the method on all other instances of the same or derived class? I wrote an example to make my question more clear. public abstract class BaseClass { private readonly object NonStaticLockObject = new object(); private static readonly object StaticLockObject = new object(); protected void DoThreadSafeAction<T>(Action<T> action) where T: BaseClass { var derived = this as T; if(derived == null) { throw new Exception(); } lock(NonStaticLockObject) { action(derived); } } } public class DerivedClass :BaseClass { private readonly Queue<object> _queue; public void Enqueue(object obj) { DoThreadSafeAction<DerivedClass>(x=>x._queue.Enqueue(obj)); } } If I make the lock on the StaticLockObject, then the DoThreadSafeAction method will be locked for all instances of all classes that derive from BaseClass and that is not what I want. I want to make sure that no other threads can call a method on a particular instance of an object while it is locked.

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• Problem with loading a PNG image in JApplet.

  - by Bruce

  Hi there, I'm trying to load a PNG image from JAR file when running JApplet. The file is, I think, loaded properly - there are no errors. However it is not displayed. img.png is placed in the same directory as MainClass.java file. Here is the code: InputStream imageURL = this.getClass().getResourceAsStream("img.png" ); byte[] bytes = null; try {bytes = new byte[imageURL.available()]; System.out.println(imageURL.available()); imageURL.read(bytes);} catch(Exception e) {System.out.println("bleah");} Image image = Toolkit.getDefaultToolkit().createImage(bytes); Image imageScaled = me.getScaledInstance( 100, 150, Image.SCALE_SMOOTH ); jLabel6 = new javax.swing.JLabel( new ImageIcon( imageScaled) ); and the HTML exerpt: <APPLET codebase="classes" code="myapplet/MainClass.class" archive ="LittleApplet.jar" width=700 height=500> The image, as I wrote, is probably read, but not displayed in JLabel. What am I missing/doing wrong? Thanks in advance for the reply!

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• Why doesn't the Java Collections API include a Graph implementation?

  - by dvanaria

  I’m currently learning the Java Collections API and feel I have a good understanding of the basics, but I’ve never understood why this standard API doesn’t include a Graph implementation. The three base classes are easily understandable (List, Set, and Map) and all their implementations in the API are mostly straightforward and consistent. Considering how often graphs come up as a potential way to model a given problem, this just doesn’t make sense to me (it’s possible it does exist in the API and I’m not looking in the right place of course). Steve Yegge suggests in one of his blog posts that a programmer should consider graphs first when attacking a problem, and if the problem domain doesn’t fit naturally into this data structure, only then consider the alternative structures. My first guess is that there is no universal way to represent graphs, or that their interfaces may not be generic enough for an API implementation to be useful? But if you strip down a graph to its basic components (vertices and a set of edges that connect some or all of the vertices) and consider the ways that graphs are commonly constructed (methods like addVertex(v) and insertEdge(v1, v2)) it seems that a generic Graph implementation would be possible and useful. Thanks for helping me understand this better.

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• Am I doing it right?

  - by LuckySlevin

  I have situation. I have to create a Sports Club system in JAVA. There should be a class your for keeping track of club name, president name and braches the club has. For each sports branch also there should be a class for keeping track of a list of players. Also each player should have a name, number, position and salary. So, I come up with this. Three seperate classes: public class Team { String clubName; String preName; Branch []branches; } public class Branch { Player[] players; } public class Player { String name; String pos; int salary; int number; } The problems are creating Branch[] in another class and same for the Player[]. Is there any simplier thing to do this? For example, I want to add info for only the club name, president name and branches of the club, in this situation, won't i have to enter players,names,salaries etc. since they are nested in each other. I hope i could be clear. For further questions you can ask.

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• Appengine JDO dataclasses to python model

  - by M.A. Cape

  Does anyone have tried to implement an app in GAE having both java and python? I have an existing app and my front end is in java. Now I want to use the existing datastore to be interfaced by python. My problem is i don't know how to define the relationships and model that would be equivalent to the one in java. I have tried the one-to-many relationship in python but when stored in the datastore, the fields are different than the one-to-many of java. My data classes are as follows. //one-to-many owned Parent Class public class Parent{ @PrimaryKey @Persistent private String unitID; //some other fields... @Persistent @Order(extensions = @Extension(vendorName="datanucleus", key="list-ordering", value="dateCreated desc")) private List <Child> child; //methods & constructors were omitted } Child public class Child{ @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) private Key uId; @Persistent private String name; /* etc... */ }

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