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  • Use continue or Checked Exceptions when checking and processing objects

    - by Johan Pelgrim
    I'm processing, let's say a list of "Document" objects. Before I record the processing of the document successful I first want to check a couple of things. Let's say, the file referring to the document should be present and something in the document should be present. Just two simple checks for the example but think about 8 more checks before I have successfully processed my document. What would have your preference? for (Document document : List<Document> documents) { if (!fileIsPresent(document)) { doSomethingWithThisResult("File is not present"); continue; } if (!isSomethingInTheDocumentPresent(document)) { doSomethingWithThisResult("Something is not in the document"); continue; } doSomethingWithTheSucces(); } Or for (Document document : List<Document> documents) { try { fileIsPresent(document); isSomethingInTheDocumentPresent(document); doSomethingWithTheSucces(); } catch (ProcessingException e) { doSomethingWithTheExceptionalCase(e.getMessage()); } } public boolean fileIsPresent(Document document) throws ProcessingException { ... throw new ProcessingException("File is not present"); } public boolean isSomethingInTheDocumentPresent(Document document) throws ProcessingException { ... throw new ProcessingException("Something is not in the document"); } What is more readable. What is best? Is there even a better approach of doing this (maybe using a design pattern of some sort)? As far as readability goes my preference currently is the Exception variant... What is yours?

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  • Why do case class companion objects extend FunctionN?

    - by retronym
    When you create a case class, the compiler creates a corresponding companion object with a few of the case class goodies: an apply factory method matching the primary constructor, equals, hashCode, and copy. Somewhat oddly, this generated object extends FunctionN. scala> case class A(a: Int) defined class A scala> A: (Int => A) res0: (Int) => A = <function1> This is only the case if: There is no manually defined companion object There is exactly one parameter list There are no type arguments The case class isn't abstract. Seems like this was added about two years ago. The latest incarnation is here. Does anyone use this, or know why it was added? It increases the size of the generated bytecode a little with static forwarder methods, and shows up in the #toString() method of the companion objects: scala> case class A() defined class A scala> A.toString res12: java.lang.String = <function0>

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  • Delphi : Handling the fact that Strings are not Objects

    - by awmross
    I am trying to write a function that takes any TList and returns a String representation of all the elements of the TList. I tried a function like so function ListToString(list:TList<TObject>):String; This works fine, except you can't pass a TList to it. E2010 Incompatible types: 'TList<System.TObject>' and 'TList<System.string>' In Delphi, a String is not an Object. To solve this, I've written a second function: function StringListToString(list:TList<string>):String; Is this the only solution? Are there other ways to treat a String as more 'object-like'? In a similar vein, I also wanted to write an 'equals' function to compare two TLists. Again I run into the same problem function AreListsEqual(list1:TList<TObject>; list2:TList<TObject>):boolean; Is there any way to write this function (perhaps using generics?) so it can also handle a TList? Are there any other tricks or 'best practises' I should know about when trying to create code that handles both Strings and Objects? Or do I just create two versions of every function? Can generics help? I am from a Java background but now work in Delphi. It seems they are lately adding a lot of things to Delphi from the Java world (or perhaps the C# world, which copied them from Java). Like adding equals() and hashcode() to TObject, and creating a generic Collections framework etc. I'm wondering if these additions are very practical if you can't use Strings with them.

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  • Recycle Freed Objects

    - by uray
    suppose I need to allocate and delete object on heap frequently (of arbitrary size), is there any performance benefit if instead of deleting those objects, I will return it back to some "pool" to be reused later? would it give benefit by reduce heap allocation/deallocation?, or it will be slower compared to memory allocator performance, since the "pool" need to manage a dynamic collection of pointers. my use case: suppose I create a queue container based on linked list, and each node of that list are allocated on the heap, so every call to push() and pop() will allocate and deallocate that node: ` template <typename T> struct QueueNode { QueueNode<T>* next; T object; } template <typename T> class Queue { void push(T object) { QueueNode<T>* newNode = QueueNodePool<T>::get(); //get recycled node if(!newNode) { newNode = new QueueNode<T>(object); } // push newNode routine here.. } T pop() { //pop routine here... QueueNodePool<T>::store(unusedNode); //recycle node return unusedNode->object; } } `

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  • Overriding to_xml for collection of ActiveRecord objects

    - by Chirantan
    Okay, I know you can override the to_xml method for a single instance of ActiveRecord object and it works just fine for me. But how would I go about overriding the to_xml method for collection of objects? Suppose for Task model instance, I implemented to_xml which looks like this. def to_xml super(:methods => [:tag_list], :include => {:project => {:include => {:folder => {}}}, :folder => {}}) end Works just fine when a single task is to be serialized to xml. But when my code runs for collection of tasks, like in the following piece of code render :xml => @tasks.to_xml I get wrong number of arguments (1 for 0) /home/chirantan/.gem/ruby/1.8/gems/activesupport-2.3.5/lib/active_support/core_ext/array/conversions.rb:189:in `to_xml' /home/chirantan/.gem/ruby/1.8/gems/activesupport-2.3.5/lib/active_support/core_ext/array/conversions.rb:189:in `to_xml' /home/chirantan/.gem/ruby/1.8/gems/activesupport-2.3.5/lib/active_support/core_ext/array/conversions.rb:189:in `each' /home/chirantan/.gem/ruby/1.8/gems/activesupport-2.3.5/lib/active_support/core_ext/array/conversions.rb:189:in `to_xml' /var/lib/gems/1.8/gems/builder-2.1.2/lib/builder/xmlbase.rb:134:in `call' /var/lib/gems/1.8/gems/builder-2.1.2/lib/builder/xmlbase.rb:134:in `_nested_structures' /var/lib/gems/1.8/gems/builder-2.1.2/lib/builder/xmlbase.rb:58:in `method_missing' /var/lib/gems/1.8/gems/builder-2.1.2/lib/builder/xmlbase.rb:31:in `tag!' /~/blah/app/controllers/tasks_controller.rb:412:in `completed' How do I make this work?

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  • Inereritance of clousure objects and overriding of methods

    - by bobikk
    I need to extend a class, which is encapsulated in a closure. This base class is following: var PageController = (function(){ // private static variable var _current_view; return function(request, new_view) { ... // priveleged public function, which has access to the _current_view this.execute = function() { alert("PageController::execute"); } } })();` Inheritance is realised using the following function: function extend(subClass, superClass){ var F = function(){ }; F.prototype = superClass.prototype; subClass.prototype = new F(); subClass.prototype.constructor = subClass; subClass.superclass = superClass.prototype; StartController.cache = ''; if (superClass.prototype.constructor == Object.prototype.constructor) { superClass.prototype.constructor = superClass; } } I subclass the PageController: var StartController = function(request){ // calling the constructor of the super class StartController.superclass.constructor.call(this, request, 'start-view'); } // extending the objects extend(StartController, PageController); // overriding the PageController::execute StartController.prototype.execute = function() { alert('StartController::execute'); } Inheritance is working. I can call every PageController's method from StartController's instance. However, method overriding doesn't work: var startCont = new StartController(); startCont.execute(); alerts "PageController::execute". How should I override this method?

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  • jquery - problem with executing annimation of two separate objects, one after another

    - by MoreThanChaos
    Hello I have problem to put together animations of two separate objects to second one start when first one ends. I tried to use callback but it seems that i make some syntax misteakes which crash jQuery or cause some unexpected behaviour. It seems that i'm stuck so I'd like to ask You for best way to put these animations together to act the way I want. in mouseenter 1st .pp grows, 2nd .tt fade in in mouseleave 1st .tt fade out, 2nd .pp shrink It's alsp relevant that animations doesn't pile up, i mean here animation called by one event doesnt wait until other animation in progress will end. In generall exactly what is below but yo be animated one after another, not simultanously. $('.pp').bind({ mouseenter: function() { $(this).animate({ width: $(this).children(".tt").outerWidth(), height: $(this).children(".tt").outerHeight() },{duration:1000,queue:false} ); $(this).children(".tt").animate({ opacity: 1.0 }, {duration:1000,queue:false}); }, mouseleave: function() { $(this).children(".tt").animate({ opacity: 0 }, {duration:1000,queue:false}); $(this).animate({ width: 17, height: 17 }, {duration:1000,queue:false}); } });

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  • iphone NSMutableArray loses objects at end of method

    - by Brodie4598
    Hello - in my app, an NSMutableArray is populated with an object in viewDidLoad (eventually there will be many objects but I'm just doing one til I get it working right). I also start a timer that starts a method that needs to access the NSMutableArray every few seconds. The NSMutableArray works fine in viewDidLoad, but as soon as that method is finished, it loses the object. myApp.h @interface MyApp : UIViewController { NSMutableArray *myMutableArray; NSTimer *timer; } @property (nonatomic, retain) NSMutableArray *myMutableArray; @property (nonatomic, retain) NSTimer *timer; @end myApp.m #import "MyApp.h" @implementation MyApp @synthesize myMutableArray; - (void) viewDidLoad { cycleTimer = [NSTimer scheduledTimerWithTimeInterval:4.0 target:self selector:@selector(newCycle) userInfo: nil repeats:YES]; MyObject *myCustomUIViewObject = [[MyObject alloc]init]; [myMutableArray addObject:myCustomUIViewObject]; [myCustomUIViewObject release]; NSLog(@"%i",[myMutableArray count]); /////outputs "1" } -(void) newCycle { NSLog(@"%i",[myMutableArray count]); /////outputs "0" ?? why is this?? }

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  • How to add objects to NSArray from a different class with ARC

    - by Space Dust
    I needed to convert my code to ARC. I have an NSArray that I use to draw a path. I fill the objects of NSArray values from a different class. Problem is after converting to ARC, NSArray returns always null I can not see what I am doing wrong. bug.h @interface Ladybug : CCSprite <CCTargetedTouchDelegate>{ CCArray *linePathPosition; } @property (nonatomic, strong) CCArray *linePathPosition; @end bug.m @synthesize linePathPosition; -(id) init { if( (self=[super init] )) { self.linePathPosition = [[CCArray alloc] init]; } return self; } -(void) updatePosition:(CGPoint) position { [self.linePathPosition addObject:[NSValue valueWithCGPoint:position]]; NSLog(@"line path %@",linePathPosition); } -(void) breakMoveLadyBug { [self.linePathPosition removeAllObjects]; } In main .m - (void)ccTouchMoved:(UITouch *)touch withEvent:(UIEvent *)event { Ladybug *ladybug1 = (Ladybug *)[self getChildByTag:99]; CCMotionStreak* streak = (CCMotionStreak *)[self getChildByTag:999]; CGPoint touchLocation = [touch locationInView: [touch view]]; CGPoint curPosition = [[CCDirector sharedDirector] convertToGL:touchLocation]; if (ladybug1.isSelected) { streak.position = curPosition; [ladybug1 updatePosition:curPosition]; NSLog(@"Cur position %@",NSStringFromCGPoint(curPosition)); if (!ladybug1.isMoving) { [ladybug1 startMoveLadyBug]; } } } Log: Cur position {331, 110} line path (null) What am I doing wrong? What is the proper way to define and init NSArray with ARC?

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  • Hibernate: Querying objects by attributes of inherited classes

    - by MichaelD
    Hi all, I ran into a problem with Hibernate concerning queries on classes which use inheritance. Basically I've the following class hierarchy: @Entity @Table( name = "recording" ) class Recording { ClassA attributeSet; ... } @Entity @Inheritance( strategy = InheritanceType.JOINED ) @Table( name = "classA" ) public class ClassA { String Id; ... } @Entity @Table( name = "ClassB1" ) @PrimaryKeyJoinColumn( name = "Id" ) public class ClassB1 extends ClassA { private Double P1300; private Double P2000; } @Entity @Table( name = "ClassB2" ) @PrimaryKeyJoinColumn( name = "Id" ) public class ClassB2 extends ClassA { private Double P1300; private Double P3000; } The hierarchy is already given like this and I cannot change it easily. As you can see ClassB1 and ClassB2 inherit from ClassA. Both classes contain a set of attributes which sometimes even have the same names (but I can't move them to ClassA since there are possible more sub-classes which do not use them). The Recording class references one instance of one of this classes. Now my question: What I want to do is selecting all Recording objects in my database which refer to an instance of either ClassB1 or ClassB2 with e.g. the field P1300 == 15.5 (so this could be ClassB1 or ClassB2 instances since the P1300 attribute is declared in both classes). What I tried is something like this: Criteria criteria = session.createCriteria(Recording.class); criteria.add( Restrictions.eq( "attributeSet.P1300", new Double(15.5) ) ); criteria.list(); But since P1300 is not an attribute of ClassA hibernate throws an exception telling me: could not resolve property: P1300 of: ClassA How can I tell hibernate that it should search in all subclasses to find the attribute I want to filter? Thanks MichaelD

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  • Remove duplicate records/objects uniquely identified by multiple attributes

    - by keruilin
    I have a model called HeroStatus with the following attributes: id user_id recordable_type hero_type (can be NULL!) recordable_id created_at There are over 100 hero_statuses, and a user can have many hero_statuses, but can't have the same hero_status more than once. A user's hero_status is uniquely identified by the combination of recordable_type + hero_type + recordable_id. What I'm trying to say essentially is that there can't be a duplicate hero_status for a specific user. Unfortunately, I didn't have a validation in place to assure this, so I got some duplicate hero_statuses for users after I made some code changes. For example: user_id = 18 recordable_type = 'Evil' hero_type = 'Halitosis' recordable_id = 1 created_at = '2010-05-03 18:30:30' user_id = 18 recordable_type = 'Evil' hero_type = 'Halitosis' recordable_id = 1 created_at = '2009-03-03 15:30:00' user_id = 18 recordable_type = 'Good' hero_type = 'Hugs' recordable_id = 1 created_at = '2009-02-03 12:30:00' user_id = 18 recordable_type = 'Good' hero_type = NULL recordable_id = 2 created_at = '2009-012-03 08:30:00' (Last two are not a dups obviously. First two are.) So what I want to do is get rid of the duplicate hero_status. Which one? The one with the most-recent date. I have three questions: How do I remove the duplicates using a SQL-only approach? How do I remove the duplicates using a pure Ruby solution? Something similar to this: http://stackoverflow.com/questions/2790004/removing-duplicate-objects. How do I put a validation in place to prevent duplicate entries in the future?

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  • How to store child objects on GAE using JDO from Scala

    - by Gero
    Hi, I'm have a parent-child relation between 2 classes, but the child objects are never stored. I do get an warning: "org.datanucleus.store.appengine.MetaDataValidator checkForIllegalChildField: Unable to validate relation net.vermaas.kivanotify.model.UserCriteria.internalCriteria" but it is unclear to me why this occurs. Already tried several alternatives without luck. The parent class is "UserCriteria" which has a List of "Criteria" as children. The classes are defined as follows (Scala): class UserCriteria(tu: String, crit: Map[String, String]) extends LogHelper { @PrimaryKey @Persistent{val valueStrategy = IdGeneratorStrategy.IDENTITY} var id = KeyFactory.createKey("UserCriteria", System.nanoTime) @Persistent var twitterUser = tu @Persistent var internalCriteria: java.util.List[Criteria] = flatten(crit) def flatten(crits: Map[String, String]) : java.util.List[Criteria] = { val list = new java.util.ArrayList[Criteria] for (key <- crits.keySet) { list.add(new Criteria(this, key, crits(key))) } list } def criteria: Map[String, String] = { val crits = mutable.Map.empty[String, String] for (i <- 0 to internalCriteria.size-1) { crits(internalCriteria.get(i).name) = internalCriteria.get(i).value } Map.empty ++ crits } // Stripped the equals, canEquals, hashCode, toString code to keep the code snippet short... } @PersistenceCapable @EmbeddedOnly class Criteria(uc: UserCriteria, nm: String, vl: String) { @Persistent var userCriteria = uc @Persistent var name = nm @Persistent var value = vl override def toString = { "Criteria name: " + name + " value: " + value } } Any ideas why the childs are not stored? Or why I get the error message? Thanks, Gero

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  • how to read in a list of custom configuration objects

    - by Johnny
    hi, I want to implement Craig Andera's custom XML configuration handler in a slightly different scenario. What I want to be able to do is to read in a list of arbitrary length of custom objects defined as: public class TextFileInfo { public string Name { get; set; } public string TextFilePath { get; set; } public string XmlFilePath { get; set; } } I managed to replicate Craig's solution for one custom object but what if I want several? Craig's deserialization code is: public class XmlSerializerSectionHandler : IConfigurationSectionHandler { public object Create(object parent, object configContext, XmlNode section) { XPathNavigator nav = section.CreateNavigator(); string typename = (string)nav.Evaluate("string(@type)"); Type t = Type.GetType(typename); XmlSerializer ser = new XmlSerializer(t); return ser.Deserialize(new XmlNodeReader(section)); } } I think I could do this if I could get Type t = Type.GetType("System.Collections.Generic.List<TextFileInfo>") to work but it throws Could not load type 'System.Collections.Generic.List<Test1.TextFileInfo>' from assembly 'Test1, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'.

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  • Access modifiers - Property on business objects - getting and setting

    - by Mike
    Hi, I am using LINQ to SQL for the DataAccess layer. I have similar business objects to what is in the data access layer. I have got the dataprovider getting the message #23. On instantiation of the message, in the message constructor, it gets the MessageType and makes a new instance of MessageType class and fills in the MessageType information from the database. Therefore; I want this to get the Name of the MessageType of the Message. user.Messages[23].MessageType.Name I also want an administrator to set the MessageType user.Messages[23].MessageType = MessageTypes.LoadType(3); but I don't want the user to publicly set the MessageType.Name. But when I make a new MessageType instance, the access modifier for the Name property is public because I want to set that from an external class (my data access layer). I could change this to property to internal, so that my class can access it like a public variable, and not allow my other application access to modify it. This still doesn't feel right as it seems like a public property. Are public access modifiers in this situation bad? Any tips or suggestions would be appreciated. Thanks.

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  • Property on business objects - getting and setting

    - by Mike
    Hi, I am using LINQ to SQL for the DataAccess layer. I have similar business objects to what is in the data access layer. I have got the dataprovider getting the message #23. On instantiation of the message, in the message constructor, it gets the MessageType and makes a new instance of MessageType class and fills in the MessageType information from the database. Therefore; I want this to get the Name of the MessageType of the Message. user.Messages[23].MessageType.Name I also want an administrator to set the MessageType user.Messages[23].MessageType = MessageTypes.LoadType(3); but I don't want the user to publicly set the MessageType.Name. But when I make a new MessageType instance, the access modifier for the Name property is public because I want to set that from an external class (my data access layer). I could change this to property to internal, so that my class can access it like a public variable, and not allow my other application access to modify it. This still doesn't feel right as it seems like a public property. Are public access modifiers in this situation bad? Any tips or suggestions would be appreciated. Thanks.

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  • Expression Blend doesn't recognize command objects declared in code behind file

    - by Brian Ensink
    I have a WPF UserControl. The code behind file declares some RoutedUICommand objects which are referenced in the XAML. The application builds and runs just fine. However Expression Blend 3 cannot load the XAML in the designer and gives errors like this one: The member "ResetCameraCommand" is not recognized or accessible. The class and the member are both public. Building and rebuilding the project in Blend and restarting Blend hasn't helped. Any ideas what the problem is? Here are fragments of my XAML ... <UserControl x:Class="CAP.Visual.CameraAndLightingControl" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="clr-namespace:CAP.Visual;assembly=VisualApp" Height="100" Width="700"> <UserControl.CommandBindings> <CommandBinding Command="local:CameraAndLightingControl.ResetCameraCommand" Executed="ResetCamera_Executed" CanExecute="ResetCamera_CanExecute"/> </UserControl.CommandBindings> .... ... and the code behind C# namespace CAP.Visual { public partial class CameraAndLightingControl : UserControl { public readonly static RoutedUICommand ResetCameraCommand; static CameraAndLightingControl() { ResetCameraCommand = new RoutedUICommand("Reset Camera", "ResetCamera", typeof(CameraAndLightingControl)); }

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  • Assign sage variable values into R objects via sagetex and Sweave

    - by sheed03
    I am writing a short Sweave document that outputs into a Beamer presentation, in which I am using the sagetex package to solve an equation for two parameters in the beta binomial distribution, and I need to assign the parameter values into the R session so I can do additional processing on those values. The following code excerpt shows how I am interacting with sage: <<echo=false,results=hide>>= mean.raw <- c(5, 3.5, 2) theta <- 0.5 var.raw <- mean.raw + ((mean.raw^2)/theta) @ \begin{frame}[fragile] \frametitle{Test of Sage 2} \begin{sagesilent} var('a1, b1, a2, b2, a3, b3') eqn1 = [1000*a1/(a1+b1)==\Sexpr{mean.raw[1]}, ((1000*a1*b1)*(1000+a1+b1))/((a1+b1)^2*(a1+b1+1))==\Sexpr{var.raw[1]}] eqn2 = [1000*a2/(a2+b2)==\Sexpr{mean.raw[2]}, ((1000*a2*b2)*(1000+a2+b2))/((a2+b2)^2*(a2+b2+1))==\Sexpr{var.raw[2]}] eqn3 = [1000*a3/(a3+b3)==\Sexpr{mean.raw[3]}, ((1000*a3*b3)*(1000+a3+b3))/((a3+b3)^2*(a3+b3+1))==\Sexpr{var.raw[3]}] s1 = solve(eqn1, a1,b1) s2 = solve(eqn2, a2,b2) s3 = solve(eqn3, a3,b3) \end{sagesilent} Solutions of Beta Binomial Parameters: \begin{itemize} \item $\sage{s1[0]}$ \item $\sage{s2[0]}$ \item $\sage{s3[0]}$ \end{itemize} \end{frame} Everything compiles just fine, and in that slide I am able to see the solutions to the three equations respective parameters in that itemized list (for example the first item in the itemized list from that beamer slide is outputted as [a1=(328/667), b1=(65272/667)] (I am not able to post an image of the beamer slide but I hope you get the idea). I would like to save the parameter values a1,b1,a2,b2,a3,b3 into R objects so that I can use them in simulations. I cannot find any documentation in the sagetex package on how to save output from sage commands into variables for use with other programs (in this case R). Any suggestions on how to get these values into R?

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  • Is there a pattern for initializing objects created wth a DI container

    - by Igor Zevaka
    I am trying to get Unity to manage the creation of my objects and I want to have some initialization parameters that are not known until run-time: At the moment the only way I could think of the way to do it is to have an Init method on the interface. interface IMyIntf { void Initialize(string runTimeParam); string RunTimeParam { get; } } Then to use it (in Unity) I would do this: var IMyIntf = unityContainer.Resolve<IMyIntf>(); IMyIntf.Initialize("somevalue"); In this scenario runTimeParam param is determined at run-time based on user input. The trivial case here simply returns the value of runTimeParam but in reality the parameter will be something like file name and initialize method will do something with the file. This creates a number of issues, namely that the Initialize method is available on the interface and can be called multiple times. Setting a flag in the implementation and throwing exception on repeated call to Initialize seems way clunky. At the point where I resolve my interface I don't want to know anything about the implementation of IMyIntf. What I do want, though, is the knowledge that this interface needs certain one time initialization parameters. Is there a way to somehow annotate(attributes?) the interface with this information and pass those to framework when the object is created? Edit: Described the interface a bit more.

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  • Java: creating objects of arrays with different names at runtime and accessing/updating them

    - by scriptingalias
    Hello, I'm trying to create a class that can instantiate arrays at runtime by giving each array a "name" created by the createtempobjectname() method. I'm having trouble making this program run. I would also like to see how I could access specific objects that were created during runtime and accessing those arrays by either changing value or accessing them. This is my mess so far, which compiles but gets a runtime exception. import java.lang.reflect.Array; public class arrays { private static String temp; public static int name = 0; public static Object o; public static Class c; public static void main(String... args) { assignobjectname(); //getclassname();//this is supposed to get the name of the object and somehow //allow the arrays to become updated using more code? } public static void getclassname() { String s = c.getName(); System.out.println(s); } public static void assignobjectname()//this creates the object by the name returned { //createtempobjectname() try { String object = createtempobjectname(); c = Class.forName(object); o = Array.newInstance(c, 20); } catch (ClassNotFoundException exception) { exception.printStackTrace(); } } public static String createtempobjectname() { name++; temp = Integer.toString(name); return temp; } }

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  • computes the number of possible orderings of n objects under the relations < and =

    - by hilal
    Here is the problem : Give a algorithm that takes a positive integer n as input, and computes the number of possible orderings of n objects under the relations < and =. For example, if n = 3 the 13 possible orderings are as follows: a = b = c, a = b < c, a < b = c, a < b < c, a < c < b, a = c < b, b < a = c, b < a < c, b < c < a, b = c < a, c < a = b, c < a < b, c < b < a. Your algorithm should run in time polynomial in n. I'm null to this problem. Can you find any solution to this dynamic-programming problem?

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  • changing the serialization procedure for a graph of objects (.net framework)

    - by pierusch
    Hello I'm developing a scientific application using .net framework. The application depends heavily upon a large data structure (a tree like structure) that has been serialized using a standard binaryformatter object. The graph structure looks like this: <serializable()>Public class BigObjet inherits list(of smallObject) end class <serializable()>public class smallObject inherits list(of otherSmallerObjects) end class ... The binaryFormatter object does a nice job but it's not optimized at all and the entire data structure reaches around 100Mb on my filesystem. Deserialization works too but it's pretty slow (around 30seconds on my quad core). I've found a nice .dll on codeproject (see "optimizing serialization...") so I wrote a modified version of the classes above overriding the default serialization/deserialization procedure reaching very good results. The problem is this: I can't lose the data previosly serialized with the old version and I'd like to be able to use the new serialization/deserialization method. I have some ideas but I'm pretty sure someone will be able to give me a proper and better advice ! use an "helper" graph of objects who takes care of the entire serialization/deserialization procedure reading data from the old format and converting them into the classes I nedd. This could work but the binaryformatter "needs" to know the types being serialized so........ :( modify the "old" graph to include a modified version of serialization procedure...so I'll be able to deserialize old file and save them with the new format......this doesn't sound too good imho. well any help will be higly highly appreciated :)

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  • Memory management of objects returned by methods (iOS / Objective-C)

    - by iOSNewb
    I am learning Objective-C and iOS programming through the terrific iTunesU course posted by Stanford (http://www.stanford.edu/class/cs193p/cgi-bin/drupal/) Assignment 2 is to create a calculator with variable buttons. The chain of commands (e.g. 3+x-y) is stored in a NSMutableArray as "anExpression", and then we sub in random values for x and y based on an NSDictionary to get a solution. This part of the assignment is tripping me up: The final two [methods] “convert” anExpression to/from a property list: + (id)propertyListForExpression:(id)anExpression; + (id)expressionForPropertyList:(id)propertyList; You’ll remember from lecture that a property list is just any combination of NSArray, NSDictionary, NSString, NSNumber, etc., so why do we even need this method since anExpression is already a property list? (Since the expressions we build are NSMutableArrays that contain only NSString and NSNumber objects, they are, indeed, already property lists.) Well, because the caller of our API has no idea that anExpression is a property list. That’s an internal implementation detail we have chosen not to expose to callers. Even so, you may think, the implementation of these two methods is easy because anExpression is already a property list so we can just return the argument right back, right? Well, yes and no. The memory management on this one is a bit tricky. We’ll leave it up to you to figure out. Give it your best shot. Obviously, I am missing something with respect to memory management because I don't see why I can't just return the passed arguments right back. Thanks in advance for any answers!

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  • linq delegate function checking from objects

    - by Philip
    I am trying to find the list of objects which can be replaced. Class Letter{ int ID; string Name; string AdvCode; int isDeleted; } Class Replacers{ int ID; string MainAdvCode; string ReplacesAdvCode; } example data: Replacers 0 455 400 1 955 400 2 955 455 such that if a Letter has and Advcode of 455 and another has a code of 400 the 400 gets marked for deletion. And then if another Letter has a 955 then the 455 gets marked for deletion and the 400 (which is already marked) is marked for deletion. The problem is with my current code the 400 and 455 is marking itself for deletion?!?!? Public class Main{ List<Letter> Letters; List<Replacers> replaces; //select the ones to replace the replacements aka the little guys //check if the replacements replacer exists if yes mark deleted var filterMethodReplacements = new Func<Letter, bool>(IsAdvInReplacements);//Working var filterMethodReplacers = new Func<Letter, bool>(IsAdvInReplacers);//NOT WORKING???? var resReplacements=letters.Where(filterMethodReplacements);//working foreach (Letter letter in resReplacements) { //select the Replacers aka the ones that contain the little guys var resReplacers = letters.Where(filterMethodReplacers); if (resReplacers != null) letter.isDeleted = 1; } } } private bool IsAdvInReplacements(Letter letter) { return (from a in Replacables where a.ReplaceAdvCode == letter.AdvCode select a).Any(); } private bool IsAdvInReplacers(Letter letter) { //?????????????????????????????? return (from a in Replacables where a.MainAdvCode == letter.AdvCode select a).Any(); } }

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  • Javascript Getting Objects to Fallback to One Another

    - by Ian
    Here's a ugly bit of Javascript it would be nice to find a workaround. Javascript has no classes, and that is a good thing. But it implements fallback between objects in a rather ugly way. The foundational construct should be to have one object that, when a property fails to be found, it falls back to another object. So if we want a to fall back to b we would want to do something like: a = {sun:1}; b = {dock:2}; a.__fallback__ = b; then a.dock == 2; But, Javascript instead provides a new operator and prototypes. So we do the far less elegant: function A(sun) { this.sun = sun; }; A.prototype.dock = 2; a = new A(1); a.dock == 2; But aside from elegance, this is also strictly less powerful, because it means that anything created with A gets the same fallback object. What I would like to do is liberate Javascript from this artificial limitation and have the ability to give any individual object any other individual object as its fallback. That way I could keep the current behavior when it makes sense, but use object-level inheritance when that makes sense. My initial approach is to create a dummy constructor function: function setFallback(from_obj, to_obj) { from_obj.constructor = function () {}; from_obj.constructor.prototype = to_obj; } a = {sun:1}; b = {dock:2}; setFallback(a, b); But unfortunately: a.dock == undefined; Any ideas why this doesn't work, or any solutions for an implementation of setFallback? (I'm running on V8, via node.js, in case this is platform dependent)

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  • Problem with passing vector of pointers to objects to member function of another object

    - by Jamesz
    Hi, I have a vector of pointers to Mouse objects called 'mice'. I'm passing the mice to the cat by reference. vector <Mouse*> mice; Cat * c; c->lookForMouse(&mice); And here's my lookForMouse() member function void Cat::lookForMouse(vector <Mouse*> *mice) { ... } And now to the problem! Within the function above, I can't seem to access my mice. This below will not work mice[i]->isActive(); The error message I receive suggests to use mice[i].isActive(), but this throws an error saying isActive() is not a member of std::vector<_Ty ... This works though... vector <Mouse*> miceCopy = *mice; miceCopy[i]->isActive(); I understand that I shouldn't be creating another vector of mice here, it defeats the whole point of passing it by reference (let me know if I'm wrong)... Why can't I do mice[i]-isActive() What should I be doing? Thanks for your time and help :D James.

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