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  • Should I use a collection here?

    - by Eva
    So I have code set up like this: public interface IInterface { public void setField(Object field); } public abstract class AbstractClass extends JPanel implements IInterface { private Object field_; public void setField(Object field) { field_ = field; } } public class ClassA extends AbstractClass { public ClassA() { // unique ClassA constructor stuff } public Dimension getPreferredSize() { return new Dimension(1, 1); } } public class ClassB extends AbstractClass { public ClassB() { // unique ClassB constructor stuff } public Dimension getPreferredSize() { return new Dimension(42, 42); } } public class ConsumerA { public ConsumerA(Collection<AbstractClass> collection) { for (AbstractClass abstractClass : collection) { abstractClass.setField(this); abstractClass.repaint(); } } } All hunky-dory so far, until public class ConsumerB { // Option 1 public ConsumerB(ClassA a, ClassB b) { methodThatOnlyTakesA(a); methodThatOnlyTakesB(b); } // Option 2 public ConsumerB(Collection<AbstractClass> collection) { for (IInterface i : collection) { if (i instanceof ClassA) { methodThatOnlyTakesA((ClassA) i); else if (i instanceof ClassB) { methodThatOnlyTakesB((ClassB) i); } } } } public class UsingOption1 { public static void main(String[] args) { ClassA a = new ClassA(); ClassB b = new ClassB(); Collection<AbstractClass> collection = Arrays.asList(a, b); ConsumerA consumerA = new ConsumerA(collection); ConsumerB consumerB = new ConsumerB(a, b); } } public class UsingOption2 { public static void main(String[] args) { Collection<AbstractClass> collection = Arrays.asList(new ClassA(), new ClassB()); ConsumerA = new ConsumerA(collection); ConsumerB = new ConsumerB(collection); } } With a lot more classes extending AbstractClass, both options get unwieldly. Option1 would make the constructor of ConsumerB really long. Also UsingOption1 would get long too. Option2 would have way more if statements than I feel comfortable with. Is there a viable Option3? If it helps, ClassA and ClassB have all the same methods, they're just implemented differently. Thanks for slogging through my code!

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  • How would i go about showing the closest paragraph element to a unique link with jQuery?

    - by Nike
    The title is a bit rusty, sorry about that. Now let me explain what i'm trying to do. I have a few listed items, like this: <li> <a id="toggle" class="0"><h4>ämne<small>2010-04-17 kl 12:54</small></h4></a> <p id="meddel" class="0">text</p> </li> <li class='odd'> <a id="toggle" class="1"><h4>test<small>2010-04-17 kl 15:01</small></h4></a> <p id="meddel" class="1">test meddelande :) [a]http://youtube.com[/a]</p> </li> The function i'm trying to achieve, is that when a user clicks a "toggle" link (the h4 text), i want the paragraph element below it to fade in. I thought of the idea of giving both the toggle link and the paragraph the same class, and then somehow make it get the paragraph with the same class as the toggle link clicked, and show it? But i'm not entirely sure how to do that either, and tbh, it doesn't sound like the greatest idea, but maybe that's the only way? I don't know... Is there some way to just simply get the nearest paragraph (below the link) with the id "meddel" and fade it in? That sounds a bit easier... I hope you can at least give me a few hints. Thanks in advance, -Nike

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  • protected abstract override Foo(); &ndash; er... what?

    - by Muljadi Budiman
    A couple of weeks back, a co-worker was pondering a situation he was facing.  He was looking at the following class hierarchy: abstract class OriginalBase { protected virtual void Test() { } } abstract class SecondaryBase : OriginalBase { } class FirstConcrete : SecondaryBase { } class SecondConcrete : SecondaryBase { } Basically, the first 2 classes are abstract classes, but the OriginalBase class has Test implemented as a virtual method.  What he needed was to force concrete class implementations to provide a proper body for the Test method, but he can’t do mark the method as abstract since it is already implemented in the OriginalBase class. One way to solve this is to hide the original implementation and then force further derived classes to properly implemented another method that will replace it.  The code will look like the following: abstract class OriginalBase { protected virtual void Test() { } } abstract class SecondaryBase : OriginalBase { protected sealed override void Test() { Test2(); } protected abstract void Test2(); } class FirstConcrete : SecondaryBase { // Have to override Test2 here } class SecondConcrete : SecondaryBase { // Have to override Test2 here } With the above code, SecondaryBase class will seal the Test method so it can no longer be overridden.  Then it also made an abstract method Test2 available, which will force the concrete classes to override and provide the proper implementation.  Calling Test will properly call the proper Test2 implementation in each respective concrete classes. I was wondering if there’s a way to tell the compiler to treat the Test method in SecondaryBase as abstract, and apparently you can, by combining the abstract and override keywords.  The code looks like the following: abstract class OriginalBase { protected virtual void Test() { } } abstract class SecondaryBase : OriginalBase { protected abstract override void Test(); } class FirstConcrete : SecondaryBase { // Have to override Test here } class SecondConcrete : SecondaryBase { // Have to override Test here } The method signature makes it look a bit funky, because most people will treat the override keyword to mean you then need to provide the implementation as well, but the effect is exactly as we desired.  The concepts are still valid: you’re overriding the Test method from its original implementation in the OriginalBase class, but you don’t want to implement it, rather you want to classes that derive from SecondaryBase to provide the proper implementation, so you also make it as an abstract method. I don’t think I’ve ever seen this before in the wild, so it was pretty neat to find that the compiler does support this case.

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  • Should accessible members of an internal class be internal too?

    - by Jeff Mercado
    I'm designing a set of APIs for some applications I'm working on. I want to keep the code style consistent in all the classes I write but I've found that there are a few inconsistencies that I'm introducing and I don't know what the best way to resolve them is. My example here is specific to C# but this would apply to any language with similar mechanisms. There are a few classes that I need for implementation purposes that I don't necessarily want to expose in the API so I make them internal whereever needed. Generally what I would do is design the class as I normally would (e.g., make members public/protected/private where necessary) and change the visibility level of the class itself to internal. So I might have a few classes that look like this: internal interface IMyItem { ItemSet AddTo(ItemSet set); } internal class _SmallItem : IMyItem { private readonly /* parameters */; public _SmallItem(/* small item parameters */) { /* ... */ } public ItemSet AddTo(ItemSet set) { /* ... */ } } internal abstract class _CompositeItem: IMyItem { private readonly /* parameters */; public _CompositeItem(/* composite item parameters */) { /* ... */ } public abstract object UsefulInformation { get; } protected void HelperMethod(/* parameters */) { /* ... */ } } internal class _BigItem : _CompositeItem { private readonly /* parameters */; public _BigItem(/* big item parameters */) { /* ... */ } public override object UsefulInformation { get { /* ... */ } } public ItemSet AddTo(ItemSet set) { /* ... */ } } In another generated class (part of a parser/scanner), there is a structure that contains fields for all possible values it can represent. The class generated is internal too but I have control over the visibility of the members and decided to make them internal as well. internal partial struct ValueType { internal string String; internal ItemSet ItemSet; internal IMyItem MyItem; } internal class TokenValue { internal static int EQ(ItemSetScanner scanner) { /* ... */ } internal static int NAME(ItemSetScanner scanner, string value) { /* ... */ } internal static int VALUE(ItemSetScanner scanner, string value) { /* ... */ } //... } To me, this feels odd because the first set of classes, I didn't necessarily have to make some members public, they very well could have been made internal. internal members of an internal type can only be accessed internally anyway so why make them public? I just don't like the idea that the way I write my classes has to change drastically (i.e., change all uses of public to internal) just because the class is internal. Any thoughts on what I should do here? It makes sense to me that I might want to make some members of a class declared public, internal. But it's less clear to me when the class is declared internal.

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  • Nullpointerexcption & abrupt IOStream closure with inheritence and subclasses

    - by user1401652
    A brief background before so we can communicate on the same wave length. I've had about 8-10 university courses on programming from data structure, to one on all languages, to specific ones such as java & c++. I'm a bit rusty because i usually take 2-3 month breaks from coding. This is a personal project that I started thinking of two years back. Okay down to the details, and a specific question, I'm having problems with my mutator functions. It seems to be that I am trying to access a private variable incorrectly. The question is, am I nesting my classes too much and trying to mutate a base class variable the incorrect way. If so point me in the way of the correct literature, or confirm this is my problem so I can restudy this information. Thanks package GroceryReceiptProgram; import java.io.*; import java.util.Vector; public class Date { private int hour, minute, day, month, year; Date() { try { BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in)); System.out.println("What's the hour? (Use 1-24 military notation"); hour = Integer.parseInt(keyboard.readLine()); System.out.println("what's the minute? "); minute = Integer.parseInt(keyboard.readLine()); System.out.println("What's the day of the month?"); day = Integer.parseInt(keyboard.readLine()); System.out.println("Which month of the year is it, use an integer"); month = Integer.parseInt(keyboard.readLine()); System.out.println("What year is it?"); year = Integer.parseInt(keyboard.readLine()); keyboard.close(); } catch (IOException e) { System.out.println("Yo houston we have a problem"); } } public void setHour(int hour) { this.hour = hour; } public void setHour() { try { BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in)); System.out.println("What hour, use military notation?"); this.hour = Integer.parseInt(keyboard.readLine()); keyboard.close(); } catch (NumberFormatException e) { System.out.println(e.toString() + ":doesnt seem to be a number"); } catch (IOException e) { System.out.println(e.toString()); } } public int getHour() { return hour; } public void setMinute(int minute) { this.minute = minute; } public void setMinute() { try (BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in))) { System.out.println("What minute?"); this.minute = Integer.parseInt(keyboard.readLine()); } catch (NumberFormatException e) { System.out.println(e.toString() + ": doesnt seem to be a number"); } catch (IOException e) { System.out.println(e.toString() + ": minute shall not cooperate"); } catch (NullPointerException e) { System.out.println(e.toString() + ": in the setMinute function of the Date class"); } } public int getMinute() { return minute; } public void setDay(int day) { this.day = day; } public void setDay() { try { BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in)); System.out.println("What day 0-6?"); this.day = Integer.parseInt(keyboard.readLine()); keyboard.close(); } catch (NumberFormatException e) { System.out.println(e.toString() + ":doesnt seem to be a number"); } catch (IOException e) { System.out.println(e.toString()); } } public int getDay() { return day; } public void setMonth(int month) { this.month = month; } public void setMonth() { try { BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in)); System.out.println("What month 0-11?"); this.month = Integer.parseInt(keyboard.readLine()); keyboard.close(); } catch (NumberFormatException e) { System.out.println(e.toString() + ":doesnt seem to be a number"); } catch (IOException e) { System.out.println(e.toString()); } } public int getMonth() { return month; } public void setYear(int year) { this.year = year; } public void setYear() { try { BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in)); System.out.println("What year?"); this.year = Integer.parseInt(keyboard.readLine()); keyboard.close(); } catch (NumberFormatException e) { System.out.println(e.toString() + ":doesnt seem to be a number"); } catch (IOException e) { System.out.println(e.toString()); } } public int getYear() { return year; } public void set() { setMinute(); setHour(); setDay(); setMonth(); setYear(); } public Vector<Integer> get() { Vector<Integer> holder = new Vector<Integer>(5); holder.add(hour); holder.add(minute); holder.add(month); holder.add(day); holder.add(year); return holder; } }; That is the Date class obviously, next is the other base class Location. package GroceryReceiptProgram; import java.io.*; import java.util.Vector; public class Location { String streetName, state, city, country; int zipCode, address; Location() { try { BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in)); System.out.println("What is the street name"); streetName = keyboard.readLine(); System.out.println("Which state?"); state = keyboard.readLine(); System.out.println("Which city?"); city = keyboard.readLine(); System.out.println("Which country?"); country = keyboard.readLine(); System.out.println("Which zipcode?");//if not u.s. continue around this step zipCode = Integer.parseInt(keyboard.readLine()); System.out.println("What address?"); address = Integer.parseInt(keyboard.readLine()); } catch (IOException e) { System.out.println(e.toString()); } } public void setZipCode(int zipCode) { this.zipCode = zipCode; } public void setZipCode() { try { BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in)); System.out.println("What zipCode?"); this.zipCode = Integer.parseInt(keyboard.readLine()); keyboard.close(); } catch (NumberFormatException e) { System.out.println(e.toString() + ":doesnt seem to be a number"); } catch (IOException e) { System.out.println(e.toString()); } } public void set() { setAddress(); setCity(); setCountry(); setState(); setStreetName(); setZipCode(); } public int getZipCode() { return zipCode; } public void setAddress(int address) { this.address = address; } public void setAddress() { try { BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in)); System.out.println("What minute?"); this.address = Integer.parseInt(keyboard.readLine()); keyboard.close(); } catch (NumberFormatException e) { System.out.println(e.toString() + ":doesnt seem to be a number"); } catch (IOException e) { System.out.println(e.toString()); } } public int getAddress() { return address; } public void setStreetName(String streetName) { this.streetName = streetName; } public void setStreetName() { try { BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in)); System.out.println("What minute?"); this.streetName = keyboard.readLine(); keyboard.close(); } catch (IOException e) { System.out.println(e.toString()); } } public String getStreetName() { return streetName; } public void setState(String state) { this.state = state; } public void setState() { try { BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in)); System.out.println("What minute?"); this.state = keyboard.readLine(); keyboard.close(); } catch (IOException e) { System.out.println(e.toString()); } } public String getState() { return state; } public void setCity(String city) { this.city = city; } public void setCity() { try { BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in)); System.out.println("What minute?"); this.city = keyboard.readLine(); keyboard.close(); } catch (IOException e) { System.out.println(e.toString()); } } public String getCity() { return city; } public void setCountry(String country) { this.country = country; } public void setCountry() { try { BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in)); System.out.println("What minute?"); this.country = keyboard.readLine(); keyboard.close(); } catch (IOException e) { System.out.println(e.toString()); } } public String getCountry() { return country; } }; their parent(What is the proper name?) class package GroceryReceiptProgram; import java.io.*; public class FoodGroup { private int price, count; private Date purchaseDate, expirationDate; private Location location; private String name; public FoodGroup() { try { setPrice(); setCount(); expirationDate.set(); purchaseDate.set(); location.set(); } catch (NullPointerException e) { System.out.println(e.toString() + ": in the constructor of the FoodGroup class"); } } public void setPrice(int price) { this.price = price; } public void setPrice() { try (BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in))) { System.out.println("What Price?"); price = Integer.parseInt(keyboard.readLine()); } catch (NumberFormatException e) { System.out.println(e.toString() + ":doesnt seem to be a number"); } catch (IOException e) { System.out.println(e.toString() + ": in the FoodGroup class, setPrice function"); } catch (NullPointerException e) { System.out.println(e.toString() + ": in FoodGroup class. SetPrice()"); } } public int getPrice() { return price; } public void setCount(int count) { this.count = count; } public void setCount() { try (BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in))) { System.out.println("What count?"); count = Integer.parseInt(keyboard.readLine()); } catch (NumberFormatException e) { System.out.println(e.toString() + ":doesnt seem to be a number"); } catch (IOException e) { System.out.println(e.toString() + ": in the FoodGroup class, setCount()"); } catch (NullPointerException e) { System.out.println(e.toString() + ": in FoodGroup class, setCount"); } } public int getCount() { return count; } public void setName(String name) { this.name = name; } public void setName() { try { BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in)); System.out.println("What minute?"); this.name = keyboard.readLine(); } catch (IOException e) { System.out.println(e.toString()); } } public String getName() { return name; } public void setLocation(Location location) { this.location = location; } public Location getLocation() { return location; } public void setPurchaseDate(Date purchaseDate) { this.purchaseDate = purchaseDate; } public void setPurchaseDate() { this.purchaseDate.set(); } public Date getPurchaseDate() { return purchaseDate; } public void setExpirationDate(Date expirationDate) { this.expirationDate = expirationDate; } public void setExpirationDate() { this.expirationDate.set(); } public Date getExpirationDate() { return expirationDate; } } and finally the main class, so I can get access to all of this work. package GroceryReceiptProgram; public class NewMain { public static void main(String[] args) { FoodGroup test = new FoodGroup(); } } If anyone is further interested, here is a link the UML for this. https://www.dropbox.com/s/1weigjnxih70tbv/GRP.dia

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  • Mapping interface or abstract class component

    - by Yann Trevin
    Please consider the following simple use case: public class Foo { public virtual int Id { get; protected set; } public virtual IBar Bar { get; set; } } public interface IBar { string Text { get; set; } } public class Bar : IBar { public virtual string Text { get; set; } } And the fluent-nhibernate map class: public class FooMap : ClassMap<Foo> { public FooMap() { Id(x => x.Id); Component(x => x.Bar, m => { m.Map(x => x.Text); }); } } While running any query with configuration, I get the following exception: NHibernate.InstantiationException: "Cannot instantiate abstract class or interface: NHMappingTest.IBar" It seems that NHibernate tries to instantiate an IBar object instead of the Bar concrete class. How to let Fluent-NHibernate know which concrete class to instantiate when the property returns an interface or an abstract base class? EDIT: Explicitly specify the type of component by writing Component<Bar> (as suggested by Sly) has no effect and causes the same exception to occur. EDIT2: Thanks to vedklyv and Paul Batum: such a mapping should be soon is now possible.

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  • Java Swingworker: Not as encapsulated class

    - by Thomas Matthews
    I'm having problems passing information, updating progress and indicating "done" with a SwingWorker class that is not an encapsulated class. I have a simple class that processes files and directories on a hard drive. The user clicks on the Start button and that launches an instance of the SwingWorker. I would like to print the names of the files that are processed on the JTextArea in the Event Driven Thread from the SwingWorker as update a progress bar. All the examples on the web are for an nested class, and the nested class accesses variables in the outer class (such as the done method). I would also like to signal the Event Driven Thread that the SwingWorker is finished so the EDT can perform actions such as enabling the Start button (and clearing fields). Here are my questions: 1. How does the SwingWorker class put text into the JTextArea of the Event Driven Thread and update a progress bar? How does the EDT determine when the {external} SwingWorker thread is finished? {I don't want the SwingWorker as a nested class because there is a lot of code (and processing) done.}

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  • Validating DataAnnotations with Validator class

    - by Pablote
    I'm trying to validate a class decorated with dataannotation with the Validator class. It works fine when the attributes are applied to the same class. But when I try to use a metadata class it doesn't work. Is there anything I should do with the Validator so it uses the metadata class? Here's some code.. this works: public class Persona { [Required(AllowEmptyStrings = false, ErrorMessage = "El nombre es obligatorio")] public string Nombre { get; set; } [Range(0, int.MaxValue, ErrorMessage="La edad no puede ser negativa")] public int Edad { get; set; } } this doesnt work: [MetadataType(typeof(Persona_Validation))] public class Persona { public string Nombre { get; set; } public int Edad { get; set; } } public class Persona_Validation { [Required(AllowEmptyStrings = false, ErrorMessage = "El nombre es obligatorio")] public string Nombre { get; set; } [Range(0, int.MaxValue, ErrorMessage = "La edad no puede ser negativa")] public int Edad { get; set; } } this is how I validate the instances: ValidationContext context = new ValidationContext(p, null, null); List<ValidationResult> results = new List<ValidationResult>(); bool valid = Validator.TryValidateObject(p, context, results, true); thanks.

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  • How to befriend a templated class's constructor?

    - by Kyle
    Why does class A; template<typename T> class B { private: A* a; public: B(); }; class A : public B<int> { private: friend B<int>::B<int>(); int x; }; template<typename T> B<T>::B() { a = new A; a->x = 5; } int main() { return 0; } result in ../src/main.cpp:15: error: invalid use of constructor as a template ../src/main.cpp:15: note: use ‘B::B’ instead of ‘B::class B’ to name the constructor in a qualified name yet changing friend B<int>::B<int>() to friend B<int>::B() results in ../src/main.cpp:15: error: no ‘void B::B()’ member function declared in class ‘B’ while removing the template completely class A; class B { private: A* a; public: B(); }; class A : public B { private: friend B::B(); int x; }; B::B() { a = new A; a->x = 5; } int main() { return 0; } compiles and executes just fine -- despite my IDE saying friend B::B() is invalid syntax?

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  • Creating instance of a service-side DataContract class on client-side in WCF

    - by hgulyan
    Hi, I have my custom class Customer with its properties. I added DataContract mark above the class and DataMember to properties and it was working fine, but I'm calling a service class's function, passing customer instance as parameter and some of my properties get 0 values. While debugging I can see my properties values and after it gets to the function, some properties' values are 0. Why it can be so? There's no code between this two actions. DataContract mark workes fine, everything's ok. Any suggestions on this issue? I tried to change ByRef to ByVal, but it doesn't change anything. Why it would pass other values right and some of integer types just 0? Maybe the answer is simple, but I can't figure it out. Thank You. <DataContract()> Public Class Customer Private Type_of_clientField As Integer = -1 <DataMember(Order:=1)> Public Property type_of_client() As Integer Get Return Type_of_clientField End Get Set(ByVal value As Integer) Type_of_clientField = value End Set End Property End Class <ServiceContract(SessionMode:=SessionMode.Allowed)> <DataContractFormat()> Public Interface CustomerService <OperationContract()> Function addCustomer(ByRef customer As Customer) As Long End Interface type_of_client properties value is 6 before I call addCustomer function. After it enters that function the value is 0. UPDATE: The issue is in instance creating. When I create an instance of a class on client side, that is stored on service side, some of my properties pass 0 or nothing, but when I call a function of a service class, that returns a new instance of that class, it works fine. What's is the difference? Could that be serialization issue?

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  • How to exclude R*.class files from a proguard build

    - by Jeremy Bell
    I am one step away from making the method described here: http://stackoverflow.com/questions/2761443/targeting-android-with-scala-2-8-trunk-builds work with a single project (vs one project for scala and one for android). I've come across a problem. Using this input file (arguments to) proguard: -injars bin;lib/scala-library.jar(!META-INF/MANIFEST.MF,!library.properties) -outjar lib/scandroid.jar -libraryjars lib/android.jar -dontwarn -dontoptimize -dontobfuscate -dontskipnonpubliclibraryclasses -dontskipnonpubliclibraryclassmembers -keepattributes Exceptions,InnerClasses,Signature,Deprecated, SourceFile,LineNumberTable,*Annotation*,EnclosingMethod -keep public class org.scala.jeb.** { public protected *; } -keep public class org.xml.sax.EntityResolver { public protected *; } Proguard successfully builds scandroid.jar, however it appears to have included the generated R classes that the android resource builder generates and compiles. In this case, they are located in bin/org/jeb/R*.class. This is not what I want. The android dalvik converter cannot build because it thinks there is a duplicate of the R class (it's in scandroid and also the R*.class files). How can I modify the above proguard arguments to exclude the R*.class files from the scandroid.jar so the dalvik converter is happy? Edit: I should note that I tried adding ;bin/org/jeb/R.class;etc... to the -libraryjars argument, and that only seemed to cause it to complain about duplicate classes, and in addition proguard decided to exclude my scala class files too.

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  • Base class deleted before subclass during python __del__ processing

    - by Oddthinking
    Context I am aware that if I ask a question about Python destructors, the standard argument will be to use contexts instead. Let me start by explaining why I am not doing that. I am writing a subclass to logging.Handler. When an instance is closed, it posts a sentinel value to a Queue.Queue. If it doesn't, a second thread will be left running forever, waiting for Queue.Queue.get() to complete. I am writing this with other developers in mind, so I don't want a failure to call close() on a handler object to cause the program to hang. Therefore, I am adding a check in __del__() to ensure the object was closed properly. I understand circular references may cause it to fail in some circumstances. There's not a lot I can do about that. Problem Here is some simple example code: explicit_delete = True class Base: def __del__(self): print "Base class cleaning up." class Sub(Base): def __del__(self): print "Sub-class cleaning up." Base.__del__(self) x = Sub() if explicit_delete: del x print "End of thread" When I run this I get, as expected: Sub-class cleaning up. Base class cleaning up. End of thread If I set explicit_delete to False in the first line, I get: End of thread Sub-class cleaning up. Exception AttributeError: "'NoneType' object has no attribute '__del__'" in <bound method Sub.__del__ of <__main__.Sub instance at 0x00F0B698>> ignored It seems the definition of Base is removed before the x._del_() is called. The Python Documentation on _del_() warns that the subclass needs to call the base-class to get a clean deletion, but here that appears to be impossible. Can you see where I made a bad step?

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  • matching an element's class to another element's ID, or *part* of another element's ID

    - by shecky
    hello again Such a simple concept but I'm struggling to express it ... apologies in advance for my verbosity. I have a container div with a class, e.g., ; I want to use that class to do two things: add a class (e.g., 'active') to the nav element whose ID matches the class of div#container (e.g., #nav-primary li# apples) add the same class to another element if part of this element's ID matches the class of #container (e.g., div#secondary-apples) I assume there's an .each() loop to check the primary nav's list items' IDs, and to check the div IDs of the secondary nav ... though the latter needs to have its prefix trimmed ... or should I say more simply if the secondary nav div IDs contain the class of div#container? I've tried a few variations of something like this: <script type="text/javascript"> $(document).ready(function() { $('#nav-primary li').each(function(){ var containerClass = $('#container').attr('class'); var secondaryID = $('#nav-primary li').attr('id'); // something like if ('#nav-primary li id' == (containerClass) { } // or should I first store a variable of the LI's ID and do something like this: if ( secondaryID == containerClass ) { } // and for the trickier part, how do I filter/trim the secondary nav div IDs, something like this: var secondaryNavID = $('#aux-left div[id ... something here to strip the 'secondary-' bit ... ]'); }); // end each }); // end doc.ready.func </script> The markup is, e.g.: ... ... ... ... ... ... ... Many thanks in advance for any suggestions, svs

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  • Editing a .class file directly, playing around with opcodes

    - by echox
    Hi, today I just tried to play a little bit around with the opcodes in compiled java class file. After inserting iinc 1,1 the java virtual machine responds with: Exception in thread "main" java.lang.ClassFormatError: Truncated class file at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClassCond(ClassLoader.java:632) at java.lang.ClassLoader.defineClass(ClassLoader.java:616) at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141) at java.net.URLClassLoader.defineClass(URLClassLoader.java:283) at java.net.URLClassLoader.access$000(URLClassLoader.java:58) at java.net.URLClassLoader$1.run(URLClassLoader.java:197) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:190) at java.lang.ClassLoader.loadClass(ClassLoader.java:307) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301) at java.lang.ClassLoader.loadClass(ClassLoader.java:248) Could not find the main class: Test. Program will exit. This is my example source code: public class Test { public static void main(String[] args) { int i = 5; i++; i++; i++; System.out.println("Number: " + i + "\n"); } } The opcode for an increment is 0x84 + 2 bytes for operands. There's only one section in the resulting class file, which contains 0x84: [..] 8401 0184 0101 8401 01[..] So I would translate this as: iinc 1,1 iinc 1,1 iinc 1,1 corresponding to my i++; i++; i++; I then tried to append just 840101 to increment the variable once more, but that didn't work and resulted in the ClassFormatError. Is there anything like a checksum for the class file? I looked up the format of a classfile in http://java.sun.com/docs/books/jvms/second_edition/html/ClassFile.doc.html but could not find anything which points out to some kind of bytes_of_classfile or something. I also don't understand why the error is "Truncated Class File", because I did append something :-) I know its not a good idea to edit class files directly, but I'm just interested on the VM internals here.

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  • Cant' cast a class with multiple inheritance

    - by Jay S.
    I am trying to refactor some code while leaving existing functionality in tact. I'm having trouble casting a pointer to an object into a base interface and then getting the derived class out later. The program uses a factory object to create instances of these objects in certain cases. Here are some examples of the classes I'm working with. // This is the one I'm working with now that is causing all the trouble. // Some, but not all methods in NewAbstract and OldAbstract overlap, so I // used virtual inheritance. class MyObject : virtual public NewAbstract, virtual public OldAbstract { ... } // This is what it looked like before class MyObject : public OldAbstract { ... } // This is an example of most other classes that use the base interface class NormalObject : public ISerializable // The two abstract classes. They inherit from the same object. class NewAbstract : public ISerializable { ... } class OldAbstract : public ISerializable { ... } // A factory object used to create instances of ISerializable objects. template<class T> class Factory { public: ... virtual ISerializable* createObject() const { return static_cast<ISerializable*>(new T()); // current factory code } ... } This question has good information on what the different types of casting do, but it's not helping me figure out this situation. Using static_cast and regular casting give me error C2594: 'static_cast': ambiguous conversions from 'MyObject *' to 'ISerializable *'. Using dynamic_cast causes createObject() to return NULL. The NormalObject style classes and the old version of MyObject work with the existing static_cast in the factory. Is there a way to make this cast work? It seems like it should be possible.

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  • Case class copy() method abstraction.

    - by Joa Ebert
    I would like to know if it is possible to abstract the copy method of case classes. Basically I have something like sealed trait Op and then something like case class Push(value: Int) extends Op and case class Pop() extends Op. The first problem: A case class without arguments/members does not define a copy method. You can try this in the REPL. scala> case class Foo() defined class Foo scala> Foo().copy() <console>:8: error: value copy is not a member of Foo Foo().copy() ^ scala> case class Foo(x: Int) defined class Foo scala> Foo(0).copy() res1: Foo = Foo(0) Is there a reason why the compiler makes this exception? I think it is rather unituitive and I would expect every case class to define a copy method. The second problem: I have a method def ops: List[Op] and I would like to copy all ops like ops map { _.copy() }. How would I define the copy method in the Op trait? I get a "too many arguments" error if I say def copy(): this.type. However, since all copy() methods have only optional arguments: why is this incorrect? And, how do I do that correct? By making another method named def clone(): this.type and write everywhere def clone() = copy() for all the case classes? I hope not.

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  • Independent name of a class

    - by tobi
    We have class lua. In lua class there is a method registerFunc() which is defined: void lua::registerFun() { lua_register( luaState, "asd", luaApi::asd); lua_register( luaState, "zxc", luaApi::zxc); } lua_register is a built-in function from lua library: http://pgl.yoyo.org/luai/i/lua_register it takes static methods from luaApi class as an 3rd argument. Now some programmer wants to use the lua class, so he is forced to create his own class with definitions of the static methods, like: class luaApi { public: static int asd(); static int zxc(); }; and now is the point. I don't want (as a programmer) to create class named exactly "luaApi", but e.g. myClassForLuaApi. But for now it's not possible because it is explicitly written in the code - in lua class: lua_register( luaState, "asd", luaApi::asd); I would have to change it to: lua_register( luaState, "asd", myClassForLuaApi::asd); but I don't want to (let's assume that the programmer has no access there). If it's still not understandable, I give up. :) Thanks.

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  • Use .bat file to recursively loop through folders and get hold of .class files

    - by user320550
    HI all, This is what i'm trying to do. I have a .bat file which takes in a argument which is nothing but a folder name. What i do first is go one level up (cd ..). Now in this directory i have 3 folders and each folders have sub-folders and have .class files in them. What i want to do is recursively loop through the folders and get hold of the .class files. Once this is done i want to echo the target folder of the .class file as well as echo the name of the.class file. So c:\temp\potter\myclass.class. I would echo out c:\temp\potter\ and myclass. I'm able to do this by writing a separate bat file which works. But when i integrate this with the recursive function it seems to break. This is what i'm doing: :: call the junit classes... and save the results echo step 3... cd %1 cd .. for /r %%a in (*.class) do set Var=%%a echo Full file location %Var% for %%i in ("%Var%") do Set CF=%%~dpi Set CF=%CF:~0,-1% :LOOP If "%CF:~-1,1%"=="\" GoTo :DONE Set CF=%CF:~0,-1% GoTo :LOOP :DONE Set CF=%CF:~0,-1% echo Folder Location %CF% ::cd %CF% For %%j in ("%Var%") Do Set name=%%~nxj :: -6 because of Quotations Set name=%name:~0,-6% echo File Name %name% echo step 3 complete... However i only get the output of one directory, while i have multiple directories having .class files. This is the output i get: step 3... Full file location C:\NKCV\Project\MyActivities\6_Selenium\htmlTestCasesConve rted2JUnit\iexplore\flow2\testCase_app2.class Folder Location C:\NKCV\Project\MyActivities\6_Selenium\htmlTestCasesConverte d2JUnit\iexplore\flow2 File Name testCase_app2 step 3 complete... missing argument! usage htmltestCaseLocation for eg., "C:\NKCV\Project\MyActivities\6_Selenium\htmlTestCases" Could anyone please let me know whats wrong here? Thanks.

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  • Count the no of LI then add class to parent UL.

    - by Wazdesign
    <ul class="taglib-ratings thumbs"> <li id="qezr_yourRating"> <a href="javascript:;" class="rating rate-up "></a> </li> </ul> <ul class="taglib-ratings thumbs"> <li id="qezr_yourRating"> <a href="javascript:;" class="rating rate-up "></a> </li> <li id="qezr_yourRating"> <a href="javascript:;" class="rating rate-up "></a> </li> </ul> I want to apply the class to the UL on base of the Count of the Inner LIs. Like if it has two LI then the class should be like two-thumbs Like if it has one LI then the class should be like one-thumbs I am trying this JS but not working it returns 2 jQuery(document).ready(function(){ var countLi = $(".taglib-ratings > li").size(); alert(countLi); if(countLi == 2) { $(this).parent('.taglib-ratings').addClass('2-col'); alert ('this ul has 2 li'); } else if(countLi == 1) { $(this).parent('.taglib-ratings').addClass('2-col'); alert ('this ul has 1 li'); } else if(countLi > 2) { alert ('this ul has'+ countLi +' li'); } }); Here is the JSbin link to the same. http://jsbin.com/ofeda/edit

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  • Apply a specific class to the first item in a series with PHP

    - by Thomas
    I have a php script that echoes a series of uploaded images and I need to apply a class to the first image echoed in the series. Is this possible? For example, if I want to display 10 images and apply a class to only the first image, how would I go about it? Here is the code, I am working with: <div id="gallery"> <?php query_posts('cat=7'); while(have_posts()) { the_post(); $image_tag = wp_get_post_image('return_html=true'); $resized_img = getphpthumburl($image_tag,'h=387&w=587&zc=1'); $url = get_permalink(); $Price ='Price'; $Location = 'Location'; $title = $post->post_title; echo "<a href='$url'><img src='$resized_img' width='587' height='387' "; echo "rel=\"<div class='gallery_title'><h2>"; echo $title; echo "</h2></div>"; echo "<div class='pre_box'>Rate:</div><div class='entry'>\$"; echo get_post_meta($post->ID, $Price, true); echo "</div><div class='pre_box'>Location:</div><div class='entry'>"; echo get_post_meta($post->ID, $Location, true); echo "</div>\""; echo "'/></a>"; echo ""; } ?> On line 13, the code looks like this: echo "<a href='$url'><img src='$resized_img' width='587' height='387' "; For the first item only, I need it to look like this: echo "<a href='$url' class='show'><img src='$resized_img' width='587' height='387' ";

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  • jQuery class selectors with nested div's

    - by mboles57
    This is part of some HTML from which I need to retrieve a piece of data. The HTML is assigned to a variable called fullDescription. <p>testing</p> <div class="field field-type-text field-field-video-short-desc"> <div class="field-label">Short Description:&nbsp;</div> <div class="field-items"> <div class="field-item odd"> Demonstrates the basics of using the Content section of App Cloud Studio </div> </div> </div> <div class="field field-type-text field-field-video-id"> <div class="field-label">Video ID:&nbsp;</div> <div class="field-items"> <div class="field-item odd"> 1251462871001 </div> </div> </div> I wish to retrieve the video ID number (1251462871001). I was thinking something like this: var videoID = $(fullDescription).find(".field.field-type-text.field-field-video-id").find(".field-item.odd").html(); Although it does not generate any syntax errors, it does not retrieve the number. Thanks for helping out a jQuery noob! -Matt

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  • C++ Matrix class hierachy

    - by bpw1621
    Should a matrix software library have a root class (e.g., MatrixBase) from which more specialized (or more constrained) matrix classes (e.g., SparseMatrix, UpperTriangluarMatrix, etc.) derive? If so, should the derived classes be derived publicly/protectively/privately? If not, should they be composed with a implementation class encapsulating common functionality and be otherwise unrelated? Something else? I was having a conversation about this with a software developer colleague (I am not per se) who mentioned that it is a common programming design mistake to derive a more restricted class from a more general one (e.g., he used the example of how it was not a good idea to derive a Circle class from an Ellipse class as similar to the matrix design issue) even when it is true that a SparseMatrix "IS A" MatrixBase. The interface presented by both the base and derived classes should be the same for basic operations; for specialized operations, a derived class would have additional functionality that might not be possible to implement for an arbitrary MatrixBase object. For example, we can compute the cholesky decomposition only for a PositiveDefiniteMatrix class object; however, multiplication by a scalar should work the same way for both the base and derived classes. Also, even if the underlying data storage implementation differs the operator()(int,int) should work as expected for any type of matrix class. I have started looking at a few open-source matrix libraries and it appears like this is kind of a mixed bag (or maybe I'm looking at a mixed bag of libraries). I am planning on helping out with a refactoring of a math library where this has been a point of contention and I'd like to have opinions (that is unless there really is an objective right answer to this question) as to what design philosophy would be best and what are the pros and cons to any reasonable approach.

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  • How does object of sub-class record information about its super-class the in a Virtual Inheritance

    - by Summer_More_More_Tea
    Hi there: I encounter this problem when tackling with virtual inheritance. I remember that in a non-virtual inheritance hierarchy, object of sub-class hold an object of its direct super-class. What about virtual inheritance? In this situation, does object of sub-class hold an object of its super-class directly or just hold a pointer pointing to an object of its super-class? By the way, why the output of the following code is: sizeof(A): 8 sizeof(B): 20 sizeof(C): 32 Code: #include <iostream> using namespace std; class A{ char k[ 3 ]; public: virtual void a(){}; }; class B : public virtual A{ char j[ 3 ]; public: virtual void b(){}; }; class C : public virtual B{ char i[ 3 ]; public: virtual void c(){}; }; int main( int argc, char *argv[] ){ cout << "sizeof(A): " << sizeof( A ) << endl; cout << "sizeof(B): " << sizeof( B ) << endl; cout << "sizeof(C): " << sizeof( C ) << endl; return 0; } Thanks in advance. Kind regards.

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  • Printing the "source" class in a log statement with a log4j wrapper

    - by Dur4ndal
    My application has a homebrew logging class that I'm migrating to using log4j under the covers. However, since I'm using the homebrew class to pass the rest of the application's logging statements to log4j, the output statements are logged as coming from the wrapper class instead of the source class. Is there a way to ensure that the "correct" source is being shown besides creating new org.apache.log4j.Logger instances for every log statement? I've also tried using the Logger.log(String callerFQCN, Priority level, Object message, Throwable t) method, but it doesnt seem to be working, for example: public class Logger2 { public static org.apache.log4j.Logger log4JLogger = org.apache.log4j.Logger.getLogger(Logger2.class); public static void warning(Object source, String message) { log(source, message, Level.WARN, null) } private static void log(Object source, String message, Level level, Throwable t) { String className = source.getClass().getName(); System.out.println("Logging class should be " + className); log4JLogger.log(className, loggingLevel, message, t); } } When called by: public void testWarning() { Logger2.warning(new Integer(3), "This should warn"); } Prints: Logging class should be java.lang.Integer 2010-05-25 10:49:57,152 WARN test.Logger2 - This should warn

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  • Get the parent class of a null object (C# Reflection)

    - by Nick
    How would I get the parent class of an object that has a value of null? For example... 'Class A' contains 'int? i' which is not set to any value when the class is created. Then in some other place in the code I want to pass in 'i' as a parameter to some function. Using 'i' as the only info, I want to be able to figure out that 'Class A' "owns" 'i'. The reason for this is because 'Class A' also contains some other object, and I want to call this other object's value from that same function mentioned in the above paragraph. Could also be: public class A { public class B { public int? i; public int? j; } B classBInstance = new B(); public string s; } { ... A someClassAInstance = new A(); ... doSomething(someClassAInstance.classBInstance.i); ... } public static bool doSomething(object theObject) { string s = /* SOMETHING on theObject to get to "s" from Class A */; int someValue = (int)theObject; }

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