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  • clojure: ExceptionInInitializerError in Namespace.<init> loading from a non-default classpath

    - by Charles Duffy
    In attempting to load an AOT-compiled class from a non-default classpath, I receive the following exception: Traceback (innermost last): File "test.jy", line 10, in ? at clojure.lang.Namespace.<init>(Namespace.java:34) at clojure.lang.Namespace.findOrCreate(Namespace.java:176) at clojure.lang.Var.internPrivate(Var.java:149) at aot_demo.JavaClass.<clinit>(Unknown Source) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Class.java:247) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) java.lang.ExceptionInInitializerError: java.lang.ExceptionInInitializerError I'm able to reproduce this with the following trivial project.clj: (defproject aot-demo "0.1.0-SNAPSHOT" :dependencies [[org.clojure/clojure "1.3.0"]] :aot [aot-demo.core]) ...and src/aot_demo/core.clj defined as follows: (ns aot-demo.core (:gen-class :name aot_demo.JavaClass :methods [#^{:static true} [lower [java.lang.String] java.lang.String]])) (defn -lower [str] (.toLower str)) The following Jython script is then sufficient to trigger the bug: #!/usr/bin/jython import java.lang.Class import java.net.URLClassLoader import java.net.URL import os cl = java.net.URLClassLoader( [java.net.URL('file://%s/target/aot-demo-0.1.0-SNAPSHOT-standalone.jar' % (os.getcwd()))]) java.lang.Class.forName('aot_demo.JavaClass', True, cl) However, the exception does not occur if the test script is started with the uberjar already in the CLASSPATH variable. What's going on here? I'm trying to write a plugin for the BaseX database in Clojure; the above accurately represents how their plugin-loading mechanism works for the purpose of providing a SSCE for this problem.

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  • Fluent NHibernate Repository with subclasses

    - by reallyJim
    Having some difficulty understanding the best way to implement subclasses with a generic repository using Fluent NHibernate. I have a base class and two subclasses, say: public abstract class Person { public virtual int PersonId { get; set; } public virtual string FirstName { get; set; } public virtual string LastName { get; set; } } public class Student : Person { public virtual decimal GPA { get; set; } } public class Teacher : Person { public virtual decimal Salary { get; set; } } My Mappings are as follows: public class PersonMap : ClassMap { public PersonMap() { Table("Persons"); Id(x => x.PersonId).GeneratedBy.Identity(); Map(x => x.FirstName); Map(x => x.LastName); } } public class StudentMap : SubclassMap<Student> { public StudentMap() { Table("Students"); KeyColumn("PersonId"); Map(x => x.GPA); } } public class TeacherMap : SubclassMap<Teacher> { public TeacherMap() { Table("Teachers"); KeyColumn("PersonId"); Map(x => x.Salary); } } I use a generic repository to save/retreive/update the entities, and it works great--provided I'm working with Repository--where I already know that I'm working with students or working with teachers. The problem I run into is this: What happens when I have an ID, and need to determine the TYPE of person? If a user comes to my site as PersonId = 23, how do I go about figuring out which type of person it is?

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  • jQuery: how to create a new div, assign some attributes, and create an id from some other elements a

    - by Ronedog
    jQuery: how to create a new div, assign some attributes, and create an id from some other elements attributes? How can I accomplish this. What I've tried below is not working and I'm unsure how to make it work. What I'm trying to do is create a div and assign it some attributes, then append this div to all the < li elements that are the on the last node of my unordered list. And lastly, but most important I want to retrieve the value of the attribute called "p_node" from the < li that is being appended to and insert it in as part of the ID of the newly created div. Here's my current jQuery code: $('<div />,{id:"'+ $("#nav li:not(:has(li))").attr("p_node").val() +'_p_cont_div", class:"property_position"}').appendTo("#nav li:not(:has(li))"); Here's the HTML before the div creation: <ul> <li p_node="98" class="page_name">Category A</li> </ul> <ul> <li p_node="99" class="page_name">Category B</li> </ul> Here's what I want it to look like after the new div creation: <ul> <li p_node="98" class="page_name">Category A</li> <div id="98_p_cont_div" class="property_position"></div> </ul> <ul> <li p_node="99" class="page_name">Category B</li> <div id="99_p_cont_div" class="property_position"></div> </ul>

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  • Searching with MATCH(), AGAINST() and AS score with mysqli and php

    - by Drew
    Below is the code I am using to search my table. I have made the relevant columns FULLTEXT in the table. This doesn't return me anything. Can someone tell me what it is that i'm doing wrong? Thanks in advance. $sql = 'SELECT id,uname,class,school, MATCH(uname, class, school) AGAINST(?) AS score FROM images WHERE MATCH(uname, class, school) AGAINST(? IN BOOLEAN MODE) ORDER BY score DES'; $stmt = $db_connection->prepare($sql); $stmt->bind_param('ss',$keyword,$keyword); $stmt->execute(); $stmt->store_result(); $stmt->bind_result($id,$uname,$class,$school); $xml = "<data>".PHP_EOL; while($stmt->fetch()){ $xml .= " <person>".PHP_EOL; $xml .= " <id>$id</id>".PHP_EOL; $xml .= " <name>$uname</name>".PHP_EOL; $xml .= " <class>$class</class>".PHP_EOL; $xml .= " <school>$school</school>".PHP_EOL; $xml .= " </person>".PHP_EOL; } $xml .= "</data>"; echo $xml; Below is an image of the indexes of the table:

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  • Best practice to structure large html-based project

    - by AntonAL
    I develop Rails based website, enjoying using partials for some common "components" Recently, i faced a problem, that states with CSS interference. Styles for one component (described in css) override styles for another components. For example, one component has ... <ul class="items"> ... and another component has it too. But that ul's has different meaning in these two components. On the other hand, i want to "inherit" some styles for one component from another. For example: Let, we have one component, called "post" <div class="post"> <!-- post's stuff --> <ul class="items"> ... </ul> </div And another component, called "new-post": <div class="new-post"> <!-- post's stuff --> <ul class="items"> ... </ul> <!-- new-post's stuff --> <div class="tools">...</div> </div Post and new-post have something similar ("post's stuff") and i want to make CSS rules to handle both "post" and "new-post" New post has "subcomponents", for example - editing tools, that has also: <ul class="items"> This is where CSS rules starting to interfer - some rules, targeted for ul.items (in post and new-post) applies subcomponent of new-post, called "tools" On the one hand - i want to inherit some styles On the other hand, i want to get better incapsulation What are the best practices, to avoid such kind of problems ?

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  • Visual Studio hangs when deploying a cube

    - by Richie
    Hello All, I'm having an issue with an Analysis Services project in Visual Studio 2005. My project always builds but only occasionally deploys. No errors are reported and VS just hangs. This is my first Analysis Services project so I am hoping that there is something obvious that I am just missing. Here is the situation I have a cube that I have successfully deployed. I then make some change, e.g., adding a hierarchy to a dimension. When I try to deploy again VS hangs. I have to restart Analysis Services to regain control of VS so I can shut it down. I restart everything sometimes once, sometimes twice or more before the project will eventually deploy. This happens with any change I make there seems to be no pattern to this behaviour. Sometimes I have to delete the cube from Analysis Services before restarting everything to get a successful deploy. Also I have successfully deployed the cube, and then subsequently successfully reprocessed a dimension then when I open a query window in SQL Server Management Studio it says that it can find any cubes. As a test I have deployed a cube successfully. I have then deleted it in Analysis Services and attempted to redeploy it, without making any changes to the cube, only to have the same behaviour mentioned above. VS just hangs with no reason so I have no idea where to start hunting down the problem. It is taking 15-20 minutes to make a change as simple as setting the NameColumn of a dimension attribute. As you can imagine this is taking hours of my time so I would greatly appreciate any assistance anyone can give me.

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  • How to use Nhibernate Validator + NHib component + ddl

    - by mynkow
    I just configured my NHibValidator. My NHibernate creates the DB schema. When I set MaxLenght="20" to some property of a class then in the database the length appears in the database column. I am doing this in the NHibValidator xml file. But the problem is that I have components and cannot figure out how to achieve this behaviour. The component is configured correctly in the Customer.hbm.xml file. EDIT: Well, I found that Hibernate Validator users had the same problem two years ago. http://opensource.atlassian.com/projects/hibernate/browse/HV-25 Is this an issue for NHibernate Validator or it is fixed. If it is working tell me how please. ----------------------------------------------------- public class Customer { public virtual string Name{get;set;} public virtual Contact Contacts{ get; } } ----------------------------------------------------- public class Contact { public virtual string Address{get;set;} } ----------------------------------------------------- <?xml version="1.0" encoding="utf-8" ?> <nhv-mapping xmlns="urn:nhibernate-validator-1.0" namespace="MyNamespace" assembly="MyAssembly"> <class name="Customer"> <property name="Name"> <length max="20"/> </property> <property name="Contacts"> <notNull/> <valid/> </property> </class> </nhv-mapping> ----------------------------------------------------- <?xml version="1.0" encoding="utf-8" ?> <nhv-mapping xmlns="urn:nhibernate-validator-1.0" namespace="MyNamespace" assembly="MyAssembly"> <class name="Contact"> <property name="Address"> <length max="50"/> <valid/> </property> </class> </nhv-mapping> -----------------------------------------------------

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  • Java: jaxb Generircs

    - by Mac
    How can I get jaxb to bind to my Vector? I cannot seem to get it to bind a Vector that contains generics as it complains that it cannot recognize my class "shape" or any of its subtypes.. "[javax.xml.bind.JAXBException: class shape.shape nor any of its super class is known to this context.]"? import java.util.Vector; import javax.xml.bind.annotation.XmlAccessType; import javax.xml.bind.annotation.XmlAccessorType; import javax.xml.bind.annotation.XmlElement; import javax.xml.bind.annotation.XmlRootElement; @XmlAccessorType(XmlAccessType.NONE) @XmlRootElement(name = "XVector") public class XVector<shape> { private Vector<shape> q; public XVector() {} @XmlElement(name = "q") public Vector<shape> getVector() { return q; } public void setVector(Vector<shape> q) { this.q = q; } } I get the following errors: javax.xml.bind.MarshalException - with linked exception: [javax.xml.bind.JAXBException: class shape.Rectangle nor any of its super class is known to this context.] at com.sun.xml.internal.bind.v2.runtime.MarshallerImpl.write(MarshallerImpl.java:317) at com.sun.xml.internal.bind.v2.runtime.MarshallerImpl.marshal(MarshallerImpl.java:243) at javax.xml.bind.helpers.AbstractMarshallerImpl.marshal(AbstractMarshallerImpl.java:75) public void saveFile(File filename) { try { FileOutputStream fout = new FileOutputStream(filename); objs.setVector(objVec); JAXBContext context = JAXBContext.newInstance(XVector.class); Marshaller marshaller = context.createMarshaller(); marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true); marshaller.marshal(objs, fout); fout.close(); } catch (JAXBException e) { e.printStackTrace (); } catch (Exception ex) { JOptionPane.showMessageDialog(this, ex.toString(), "Error", JOptionPane.ERROR_MESSAGE); } }

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  • Dealing with multiple generics in a method call

    - by thaBadDawg
    I've been dealing a lot lately with abstract classes that use generics. This is all good and fine because I get a lot of utility out of these classes but now it's making for some rather ugly code down the line. For example: abstract class ClassBase<T> { T Property { get; set; } } class MyClass : ClassBase<string> { OtherClass PropertyDetail { get; set; } } This implementation isn't all that crazy, except when I want to reference the abstract class from a helper class and then I have to make a list of generics just to make reference to the implemented class, like this below. class Helper { void HelpMe<C, T>(object Value) where C : ClassBase<T>, new() { DoWork(); } } This is just a tame example, because I have some method calls where the list of where clauses end up being 5 or 6 lines long to handle all of the generic data. What I'd really like to do is class Helper { void HelpMe<C>(object Value) where C : ClassBase, new() { DoWork(); } } but it obviously won't compile. I want to reference ClassBase without having to pass it a whole array of generic classes to get the function to work, but I don't want to reference the higher level classes because there are a dozen of those. Am I the victim of my own cleverness or is there an avenue that I haven't considered yet?

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  • HTML/jQuery/CSS Drop Down Menu Issue / Safari

    - by mmundiff
    I have a drop down menu that is coded in HTML, CSS, and jQuery and it works fine in Firefox and IE but not in Safari, and also not in Firefox on Mac. The drop down displays inline as opposed to list-item for the drop down in Safari. Any ideas why? <html> <head> <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.4/jquery.min.js"></script> <script type="text/javascript" > $(document).ready(function(){ $('#menu li').hover( function() { //$('ul', this).css('display', 'block'); $('ul', this).fadeIn(200); var src = $('img.item', this).attr('src').match(/[^\.]+/) + '_over.png'; $('img.item', this).attr('src', src); }, function() { //$('ul', this).css('display', 'none'); $('ul', this).fadeOut(350); var src = $('img.item', this).attr('src').replace('_over', ''); $('img.item', this).attr('src', src); }); }); </script> <style type="text/css"> /* General */ body { arial, sans-serif; background-color: white; } * { padding: 0; margin: 0; } #menu{ white-space:nowrap; list-style:none; margin-left: 1px; } #menu ul { list-style: none; position:absolute; left:0; display:none; margin:0 -3px 0 -1px; padding:0; background: #000000; z-index: 500; margin-top: -4px; } #menu li{ display:inline; float: left; /* Added */ position:relative; } #menu li a { display: block; } #menu ul li { width:116px; float:left; border-top:1px dotted #666666; display: block; } #menu li ul { display: none; border-top: 1px black solid; text-align: left; } #menu ul a:hover { text-decoration:none; background: #efda83; color: #000000; } #menu ul a { text-decoration:none; display:block; height:15px; padding: 8px 5px; color:#efda83; font-size: 12px; } img{ border: 0 none; } .clear{ clear: both; } </style> </head> <body> <div> <ul id="menu"> <li ><a href="index.php"><img src="images/ssr_nav_home.png" class="item" alt="Home" /></a> </li> <li ><a href="about.php"><img src="images/ssr_nav_about.png" class="item" alt="About" /></a> <ul> <li><a href="about_contributors.php">Contributors</a></li> <li><a href="about_behind.php">Behind the Exhibit</a></li> <li><a href="about_sponsors.php">Sponsors</a></li> </ul> <div class="clear"></div> </li> <li ><a href="exhibit_intro.php"><img class="item" src="images/ssr_nav_exhibit.png" alt="Exhibit" /></a> <ul> <li><a href="exhibit_intro.php">Intro</a></li> <li><a href="exhibit_silkroad.php">Silk Road</a></li> <li><a href="exhibit_western_regions.php">Western Regions</a></li> <li><a href="exhibit_daily_life.php">Daily Life</a></li> <li><a href="exhibit_burial_practices.php">Burial Practices</a></li> <li><a href="exhibit_relevance.php">Relevance</a></li> </ul> <div class="clear"></div> </li> <li ><a href="visit.php"><img class="item" src="images/ssr_nav_visit.png" alt="Visit" /></a> <ul> <li><a href="visit_tickets.php">Tickets</a></li> <li><a href="visit_specials.php">Special Offers</a></li> <li><a href="visit_tours.php">Tours</a></li> <li><a href="visit_groups.php">Groups</a></li> </ul> <div class="clear"></div> </li> <li ><a href="events.php"><img class="item" src="images/ssr_nav_events.png" alt="Events" /></a> <ul> <li><a href="events_lectures.php">Lecture Series</a></li> <li><a href="events_symposium.php">Symposium</a></li> <li><a href="kids_and_family.php">Kids &amp; Family</a></li> <li><a href="events_calendar.php">Event Calendar</a></li> </ul> <div class="clear"></div> </li> <li ><a href="gallery.php"><img class="item" src="images/ssr_nav_images.png" alt="Gallery" /></a></li> <li ><a href="resources.php"><img class="item" src="images/ssr_nav_resources.png" alt="Resources" /></a> <ul> <li><a href="resources_teachers.php">For Teachers</a></li> <li><a href="kids_and_family.php">Kids &amp; Family</a></li> <li><a href="http://www.penn.museum/podcasts-and-videos/819-secrets-of-the-silk-road.html" rel="external">Podcasts &amp; Videos</a></li> <!-- <li><a href="map.php">Silk Road Map</a></li> <li><a href="resources_timeline.php">Timeline</a></li> --> <li><a href="resources_quiz.php">Quiz</a></li> <li><a href="glossary.php">Glossary</a></li> <li><a href="blogs.php">Blog</a></li> </ul> <div class="clear"></div> </li> <li ><a href="press.php"><img class="item" src="images/ssr_nav_press.png" alt="Press" /></a> <ul> <li><a href="press_release.php">Press Release</a></li> <li><a href="press_images.php">Press Images</a></li> <li><a href="press_bloggers.php">Bloggers</a></li> </ul> <div class="clear"></div> </li> </ul> </div> </body> </html>

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  • c++ Design pattern for CoW, inherited classes, and variable shared data?

    - by krunk
    I've designed a copy-on-write base class. The class holds the default set of data needed by all children in a shared data model/CoW model. The derived classes also have data that only pertains to them, but should be CoW between other instances of that derived class. I'm looking for a clean way to implement this. If I had a base class FooInterface with shared data FooDataPrivate and a derived object FooDerived. I could create a FooDerivedDataPrivate. The underlying data structure would not effect the exposed getters/setters API, so it's not about how a user interfaces with the objects. I'm just wondering if this is a typical MO for such cases or if there's a better/cleaner way? What peeks my interest, is I see the potential of inheritance between the the private data classes. E.g. FooDerivedDataPrivate : public FooDataPrivate, but I'm not seeing a way to take advantage of that polymorphism in my derived classes. class FooDataPrivate { public: Ref ref; // atomic reference counting object int a; int b; int c; }; class FooInterface { public: // constructors and such // .... // methods are implemented to be copy on write. void setA(int val); void setB(int val); void setC(int val); // copy constructors, destructors, etc. all CoW friendly private: FooDataPrivate *data; }; class FooDerived : public FooInterface { public: FooDerived() : FooInterface() {} private: // need more shared data for FooDerived // this is the ???, how is this best done cleanly? };

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  • Doubt about instance creation by using Spring framework ???

    - by Arthur Ronald F D Garcia
    Here goes a command object which needs to be populated from a Spring form public class Person { private String name; private Integer age; /** * on-demand initialized */ private Address address; // getter's and setter's } And Address public class Address { private String street; // getter's and setter's } Now suppose the following MultiActionController @Component public class PersonController extends MultiActionController { @Autowired @Qualifier("personRepository") private Repository<Person, Integer> personRepository; /** * mapped To /person/add */ public ModelAndView add(HttpServletRequest request, HttpServletResponse response, Person person) throws Exception { personRepository.add(person); return new ModelAndView("redirect:/home.htm"); } } Because Address attribute of Person needs to be initialized on-demand, i need to override newCommandObject to create an instance of Person to initiaze address property. Otherwise, i will get NullPointerException @Component public class PersonController extends MultiActionController { /** * code as shown above */ @Override public Object newCommandObject(Class clazz) thorws Exception { if(clazz.isAssignableFrom(Person.class)) { Person person = new Person(); person.setAddress(new Address()); return person; } } } Ok, Expert Spring MVC and Web Flow says Options for alternate object creation include pulling an instance from a BeanFactory or using method injection to transparently return a new instance. First option pulling an instance from a BeanFactory can be written as @Override public Object newCommandObject(Class clazz) thorws Exception { /** * Will retrieve a prototype instance from ApplicationContext whose name matchs its clazz.getSimpleName() */ getApplicationContext().getBean(clazz.getSimpleName()); } But what does he want to say by using method injection to transparently return a new instance ??? Can you show how i implement what he said ??? ATT: I know this funcionality can be filled by a SimpleFormController instead of MultiActionController. But it is shown just as an example, nothing else

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  • Prototype function to set onclick event observer in checkboxes

    - by xain
    Hi, I want to set an observer for each of the following checkboxes: <div id="listr"> <ul id="lr" style="list-style-type: none"> <p class="tir">Text 1</p> <li class="ro"><input type="checkbox" name="r1" id="r1"/>A1</li> <li class="ro"><input type="checkbox" name="r2" />A2</li> <p class="tir">Text 2</p> <li class="rubro"><input type="checkbox" name="r3" />B1</li> <p class="tir">Text 3</p> <li class="ro"><input type="checkbox" name="r4" />B2</li> </ul> </div> It works if I write one observer per checkbox, but I want to do it in a short fashion, so I need something like $$('listr.lr.li.input').invoke('observe',click,function(field) { alert(this.name + ' clicked ' + this.checked); // other stuff ... }); Which is not working Thanks in advance

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  • how to make a software and preserve database integrity and correctness and please help confused

    - by user287745
    i have made an application project in vs 08 c#, sql server from vs 08. the database has like 20 tables and many fields in each have made an interface for adding deleting editting and retrieving data according to predefined needs of the users. now i have to 1) make to project in to a software which i can deliver to professor. that is he can just double click the icon and the software simply starts. no vs 08 needed to start the debugging 2) the database will be on one powerful computer (dual core latest everything win xp) and the user will access it from another computer connected using LAN i am able to change the connection string to the shared database using vs 08/ debugger whenever the server changes but how am i supposed to do that when its a software? 3)there will by many clients am i supposed to give the same software to every one, so they all can connect to the database, how will the integrity and correctness of the database be maintained? i mean the db.mdf file will be in a folder which will be shared with read and write access. so its not necessary that only one user will write at a time. so is there any coding for this or? please help me out here i am stuck do not know what to do i have no practical experience, would appreciate all the help thank you

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  • Serializing Configurations for a Dependency Injection / Inversion of Control

    - by Joshua Starner
    I've been researching Dependency Injection and Inversion of Control practices lately in an effort to improve the architecture of our application framework and I can't seem to find a good answer to this question. It's very likely that I have my terminology confused, mixed up, or that I'm just naive to the concept right now, so any links or clarification would be appreciated. Many examples of DI and IoC containers don't illustrate how the container will connect things together when you have a "library" of possible "plugins", or how to "serialize" a given configuration. (From what I've read about MEF, having multiple declarations of [Export] for the same type will not work if your object only requires 1 [Import]). Maybe that's a different pattern or I'm blinded by my current way of thinking. Here's some code for an example reference: public abstract class Engine { } public class FastEngine : Engine { } public class MediumEngine : Engine { } public class SlowEngine : Engine { } public class Car { public Car(Engine e) { engine = e; } private Engine engine; } This post talks about "Fine-grained context" where 2 instances of the same object need different implementations of the "Engine" class: http://stackoverflow.com/questions/2176833/ioc-resolve-vs-constructor-injection Is there a good framework that helps you configure or serialize a configuration to achieve something like this without hard coding it or hand-rolling the code to do this? public class Application { public void Go() { Car c1 = new Car(new FastEngine()); Car c2 = new Car(new SlowEngine()); } } Sample XML: <XML> <Cars> <Car name="c1" engine="FastEngine" /> <Car name="c2" engine="SlowEngine" /> </Cars> </XML>

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  • Java - Call to start method on thread : how does it route to Runnable interface's run () ?

    - by Bhaskar
    Ok , I know the two standard ways to create a new thread and run it in Java : 1 Implement Runnable in a class , define run method ,and pass an instance of the class to a new Thread. When the start method on the thread instance is called , the run method of the class instance will be invoked. 2 Let the class derive from Thread, so it can to override the method run() and then when a new instance's start method is called , the call is routed to overridden method. In both methods , basically a new Thread object is created and its start method invoked. However , while in the second method , the mechanism of the call being routed to the user defined run() method is very clear ,( its a simple runtime polymorphism in play ), I dont understand how the call to start method on the Thread object gets routed to run() method of the class implementing Runnable interface. Does the Thread class have an private field of Type Runnable which it checks first , and if it is set then invokes the run method if it set to an object ? that would be a strange mechanism IMO. How does the call to start() on a thread get routed to the run method of the Runnable interface implemented by the class whose object is passed as a parameter when contructing the thread ?

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  • Observer pattern and violation of Single Responsibility Principle

    - by Devil Jin
    I have an applet which repaints itself once the text has changed Design 1: //MyApplet.java public class MyApplet extends Applet implements Listener{ private DynamicText text = null; public void init(){ text = new DynamicText("Welcome"); } public void paint(Graphics g){ g.drawString(text.getText(), 50, 30); } //implement Listener update() method public void update(){ repaint(); } } //DynamicText.java public class DynamicText implements Publisher{ // implements Publisher interface methods //notify listeners whenever text changes } Isn't this a violation of Single Responsibility Principle where my Applet not only acts as Applet but also has to do Listener job. Same way DynamicText class not only generates the dynamic text but updates the registered listeners. Design 2: //MyApplet.java public class MyApplet extends Applet{ private AppletListener appLstnr = null; public void init(){ appLstnr = new AppletListener(this); // applet stuff } } // AppletListener.java public class AppletListener implements Listener{ private Applet applet = null; public AppletListener(Applet applet){ this.applet = applet; } public void update(){ this.applet.repaint(); } } // DynamicText public class DynamicText{ private TextPublisher textPblshr = null; public DynamicText(TextPublisher txtPblshr){ this.textPblshr = txtPblshr; } // call textPblshr.notifyListeners whenever text changes } public class TextPublisher implments Publisher{ // implements publisher interface methods } Q1. Is design 1 a SPR violation? Q2. Is composition a better choice here to remove SPR violation as in design 2.

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  • Java abstract visitor - guarantueed to succeed? If so, why?

    - by disown
    I was dealing with hibernate, trying to figure out the run-time class behind proxied instances by using the visitor pattern. I then came up with an AbstractVisitable approach, but I wonder if it will always produce correct results. Consider the following code: interface Visitable { public void accept(Visitor v); } interface Visitor { public void visit(Visitable visitorHost); } abstract class AbstractVisitable implements Visitable { @Override public void accept(Visitor v) { v.visit(this); } } class ConcreteVisitable extends AbstractVisitable { public static void main(String[] args) { final Visitable visitable = new ConcreteVisitable(); final Visitable proxyVisitable = (Visitable) Proxy.newProxyInstance( Thread.currentThread().getContextClassLoader(), new Class<?>[] { Visitable.class }, new InvocationHandler() { @Override public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { return method.invoke(visitable, args); } }); proxyVisitable.accept(new Visitor() { @Override public void visit(Visitable visitorHost) { System.out.println(visitorHost.getClass()); } }); } } This makes a ConcreteVisitable which inherits the accept method from AbstractVisitable. In c++, I would consider this risky, since this in AbstractVisitable could be referencing to AbstractVisitable::this, and not ConcreteVisitable::this. I was worried that the code under certain circumstances would print class AbstractVisible. Yet the code above outputs class ConcreteVisitable, even though I hid the real type behind a dynamic proxy (the most difficult case I could come up with). Is the abstract visitor approach above guaranteed to work, or are there some pitfalls with this approach? What guarantees are given in Java with respect to the this pointer?

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  • How do you pass a generic delegate argument to a method in .NET 2.0 - UPDATED

    - by Seth Spearman
    Hello, I have a class with a delegate declaration as follows... Public Class MyClass Public Delegate Function Getter(Of TResult)() As TResult ''#the following code works. Public Shared Sub MyMethod(ByVal g As Getter(Of Boolean)) ''#do stuff End Sub End Class However, I do not want to explicitly type the Getter delegate in the Method call. Why can I not declare the parameter as follows... ... (ByVal g As Getter(Of TResult)) Is there a way to do it? My end goal was to be able to set a delegate for property setters and getters in the called class. But my reading indicates you can't do that. So I put setter and getter methods in that class and then I want the calling class to set the delegate argument and then invoke. Is there a best practice for doing this. I realize in the above example that I can set set the delegate variable from the calling class...but I am trying to create a singleton with tight encapsulation. For the record, I can't use any of the new delegate types declared in .net35. Answers in C# are welcome. Any thoughts? Seth

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  • loopedSlider jQuery plugin problem

    - by kil4
    Hi i use loopedSlider link text and there is html source. <div id="loopedSlider"> <div class="container"> <div class="slides"> <div><img src="01.jpg" alt="" /></div> <div><img src="02.jpg" alt="" /></div> <div><img src="03.jpg" alt="" /></div> <div><img src="04.jpg" alt="" /></div> </div></div><a href="#" class="previous">previous</a> <a href="#" class="next">next</a><ul class="pagination"> <li><a href="#">1</a></li> <li><a href="#">2</a></li> <li><a href="#">3</a></li> <li><a href="#">4</a></li> Is there possible to insert div like this: <div class="slides"> <div> <div class="newdiv">Some text</div> </div> </div> If i insert this div "newdiv" inside is not showing? Any solution ?

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  • Ruby: how does constant-lookup work in instance_eval/class_eval?

    - by Alan O'Donnell
    I'm working my way through Pickaxe 1.9, and I'm a bit confused by constant-lookup in instance/class_eval blocks. I'm using 1.9.2. It seems that Ruby handles constant-lookup in *_eval blocks the same way it does method-lookup: look for a definition in receiver.singleton_class (plus mixins); then in receiver.singleton_class.superclass (plus mixins); then continue up the eigenchain until you get to #<Class:BasicObject>; whose superclass is Class; and then up the rest of the ancestor chain (including Object, which stores all the constants you define at the top-level), checking for mixins along the way Is this correct? The Pickaxe discussion is a bit terse. Some examples: class Foo CONST = 'Foo::CONST' class << self CONST = 'EigenFoo::CONST' end end Foo.instance_eval { CONST } # => 'EigenFoo::CONST' Foo.class_eval { CONST } # => 'EigenFoo::CONST', not 'Foo::CONST'! Foo.new.instance_eval { CONST } # => 'Foo::CONST' In the class_eval example, Foo-the-class isn't a stop along Foo-the-object's ancestor chain! And an example with mixins: module M CONST = "M::CONST" end module N CONST = "N::CONST" end class A include M extend N end A.instance_eval { CONST } # => "N::CONST", because N is mixed into A's eigenclass A.class_eval { CONST } # => "N::CONST", ditto A.new.instance_eval { CONST } # => "M::CONST", because A.new.class, A, mixes in M

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  • Fun with casting and inheritance

    - by Vaccano
    NOTE: This question is written in a C# like pseudo code, but I am really going to ask which languages have a solution. Please don't get hung up on syntax. Say I have two classes: class AngleLabel: CustomLabel { public bool Bold; // code to allow the label to be on an angle } class Label: CustomLabel { public bool Bold; // Code for a normal label // Maybe has code not in an AngleLabel (align for example). } They both decend from this class: class CustomLabel: Control { protected bool Bold; } The bold field is exposed as public in the descended classes. No interfaces are available on the classes. Now, I have a method that I want to beable to pass in a CustomLabel and set the Bold property. Can this be done without having to 1) find out what the real class of the object is and 2) cast to that object and then 3) make seperate code for each variable of each label type to set bold. Kind of like this: public void SetBold(customLabel: CustomLabel) { AngleLabel angleLabel; NormalLabel normalLabel; if (angleLabel is AngleLabel ) { angleLabel= customLabel as AngleLabel angleLabel.Bold = true; } if (label is Label) { normalLabel = customLabel as Label normalLabel .Bold = true; } } It would be nice to maybe make one cast and and then set bold on one variable. What I was musing about was to make a fourth class that just exposes the bold variable and cast my custom label to that class. Would that work? If so, which languages would it work for? (This example is drawn from an old version of Delphi (Delphi 5)). I don't know if it would work for that language, (I still need to try it out) but I am curious if it would work for C++, C# or Java. If not, any ideas on what would work? (Remember no interfaces are provided and I can not modify the classes.) Any one have a guess?

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  • How to provide an inline model field with a queryset choices without losing field value for inline r

    - by Judith Boonstra
    The code displayed below is providing the choices I need for the app field, and the choices I need for the attr field when using Admin. I am having a problem with the attr field on the inline form for already saved records. The attr selected for these saved does show in small print above the field, but not within the field itself. # MODELS: Class Vocab(models.Model): entity = models.Charfield, max_length = 40, unique = True) Class App(models.Model): name = models.ForeignKey(Vocab, related_name = 'vocab_appname', unique = True) app = SelfForeignKey('self, verbose_name = 'parent', blank = True, null = True) attr = models.ManyToManyField(Vocab, related_name = 'vocab_appattr', through ='AppAttr' def parqs(self): a method that provides a queryset consisting of available apps from vocab, excluding self and any apps within the current app's dependent line. def attrqs(self): a method that provides a queryset consisting of available attr from vocab excluding those already selected by current app, 2) those already selected by any apps within the current app's parent line, and 3) those selected by any apps within the current app's dependent line. Class AppAttr(models.Model): app = models.ForeignKey(App) attr = models.ForeignKey(Vocab) # FORMS: from models import AppAttr def appattr_form_callback(instance, field, *args, **kwargs) if field.name = 'attr': if instance: return field.formfield(queryset = instance.attrqs(), *kwargs) return field.formfield(*kwargs) # ADMIN: necessary imports class AppAttrInline(admin.TabularInline): model = AppAttr def get_formset(self, request, obj = None, **kwargs): kwargs['formfield_callback'] = curry(appattr_form_callback, obj) return super(AppAttrInline, self).get_formset(request, obj, **kwargs) class AppForm(forms.ModelForm): class Meta: model = App def __init__(self, *args, **kwargs): super(AppForm, self).__init__(*args, **kwargs) if self.instance.id is None: working = App.objects.all() else: thisrec = App.objects.get(id = self.instance.id) working = thisrec.parqs() self.fields['par'].queryset = working class AppAdmin(admin.ModelAdmin): form = AppForm inlines = [AppAttrInline,] fieldsets = .......... necessary register statements

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  • C++ Implicit Conversion Operators

    - by Imbue
    I'm trying to find a nice inheritance solution in C++. I have a Rectangle class and a Square class. The Square class can't publicly inherit from Rectangle, because it cannot completely fulfill the rectangle's requirements. For example, a Rectangle can have it's width and height each set separately, and this of course is impossible with a Square. So, my dilemma. Square obviously will share a lot of code with Rectangle; they are quite similar. For examlpe, if I have a function like: bool IsPointInRectangle(const Rectangle& rect); it should work for a square too. In fact, I have a ton of such functions. So in making my Square class, I figured I would use private inheritance with a publicly accessible Rectangle conversion operator. So my square class looks like: class Square : private Rectangle { public: operator const Rectangle&() const; }; However, when I try to pass a Square to the IsPointInRectangle function, my compiler just complains that "Rectangle is an inaccessible base" in that context. I expect it to notice the Rectangle operator and use that instead. Is what I'm trying to do even possible? If this can't work I'm probably going to refactor part of Rectangle into MutableRectangle class. Thanks.

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  • Whose fault is a NullReferenceException?

    - by stefan.at.wpf
    I'm currently working on a class which exposes an internal List through a property. The List shall and can be modified. The problem is, entries in the internal list could be set to null from outside the class. My code actually looks like this: class ClassWithList { List<object> _list = new List<object>(); // get accessor, which however returns the reference to the list, // therefore the list can be modified (this is intended) public List<object> Data { get { return _list; } } private void doSomeWorkWithTheList() { foreach(object obj in _list) // do some work with the objects in the list without checking for null. } } So now in the doSomeWorkWithTheList() I could always check whether the current list entry is null or I could just asume that the person using this class doesn't have the great idea to set entries to null. So finally the questions end up in: Whose fault is a NullReferenceException in this case? Is it the fault of the class developer not checking everything for null (which would make code generally - not only in this class - more complex) or is it the fault of the user of this class, as setting a List entry to null doesn't really make sense? I'd tend to generally not check values for null except in some really special cases. Is this a bad style or de facto standard / standard in praxis? I know there's probably no ultimate answer for this, I'm just missing enough experience for such thing and therefore wondering what other developers think about such cases and want to hear what's done in reality about checking null (or not).

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