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  • Can a constructor return a NULL value?

    - by Sanctus2099
    I know constructors don't "return" anything but for instance if I call CMyClass *object = new CMyClass() is there any way to make object to be NULL if the constructor fails? In my case I have some images that have to be loaded and if the file reading fails I'd like it to return null. Is there any way to do that? Thanks in advance.

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  • With ARC why use @properties anymore?

    - by trapper
    In non-ARC code retained properties handily take care of memory management for you using the self.property = syntax, so we were taught to use them for practically everything. But now with ARC this memory management is no longer an issue, so does the reason for using properties evaporate? is there still any good reason (obviously other than providing public access to instance variables) to use properties anymore?

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  • Good design of mapping Java Domain objects to Tables (using Hibernate)

    - by M. McKenzie
    Hey guys, I have a question that is more in the realm of design, than implementation. I'm also happy for anyone to point out resources for the answer and I'll gladly, research for myself. Highly simplified Java and SQL: Say I have a business domain POJO called 'Picture' with three attributes. class Picture int idPicture String fileName long size Say I have another business domain POJO called "Item" with 3 attributes Class Item int idItem String itemName ArrayList itemPictures These would be a normal simple relationship. You could say that 'Picture' object, will never exist outside an 'Item' object. Assume a picture belongs only to a specific item, but that an item can have multiple pictures Now - using good database design (3rd Normal Form), we know that we should put items and pictures in their own tables. Here is what I assume would be correct. table Item int idItem (primary key) String itemName table Picture int idPicture (primary key) varchar(45) fileName long size int idItem (foreign key) Here is my question: If you are making Hibernate mapping files for these objects. In the data design, your Picture table needs a column to refer to the Item, so that a foreign key relation can be maintained. However,in your business domain objects - your Picture does not hold a reference/attribute to the idItem - and does not need to know it. A java Picture instance is always instantiated inside an Item instance. If you want to know the Item that the Picture belongs to you are already in the correct scope. Call myItem.getIdItem() and myItem.getItemPictures(),and you have the two pieces of information you need. I know that Hibernate tools have a generator that can auto make your POJO's from looking at your database. My problem stems from the fact that I planned out the data design for this experiment/project first. Then when I went to make the domain java objects, I realized that good design dictated that the objects hold other objects in a nested way. This is obviously different from the way that a database schema is - where all objects(tables) are flat and hold no other complex types within them. What is a good way to reconcile this? Would you: (A) Make the hibernate mapping files so that Picture.hbm.xml has a mapping to the POJO parent's idItem Field (if it's even possible) (B) Add an int attribute in the Picture class to refer to the idItem and set it at instantiation, thus simplifying the hbm.xml mapping file by having all table fields as local attributes in the class (C) Fix the database design because it is wrong, dork. I'd truly appreciate any feedback

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  • Dispose a Web Service Proxy class?

    - by Matt
    When you create and use a Web Service proxy class in the ASP.Net framework, the class ultimately inherits from Component, which implements IDisposable. I have never seen one example online where people dispose of a web proxy class, but was wondering if it really needs to be done. When I call only one method, I normally wrap it in a using statement, but if I have a need to call it several times throughout the page, I might end up using the same instance, and just wondered what the ramifications are of not disposing it.

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  • help me understand the method Validator.TryValidateObject()

    - by Benny
    this is the method definition: public static bool TryValidateObject( Object instance, ValidationContext validationContext, ICollection<ValidationResult> validationResults, bool validateAllProperties ) what i am confused is the validateAllProperties parameter, I understand when it is true-validate all properties. What about when it is false, not validate all properties, but which property will be validated?

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  • Spawning a interactive process

    - by notnoop
    How can a Java application spawn a new interactive application (e.g. an command line editor) from Java/Scala? When I use Runtime.getRuntime().exec("vim test"), I would only get a Process instance, while vim would be running in the background; rather then appear to the user.

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  • Alternative for assigns() in Cucumber with Capybara?

    - by thillerson
    I'm trying out capybara with cucumber to get some better javascript test coverage. I have a lot of steps that check or use things from the Rails integration test helpers, for instance: assigns(:current_user).should_not be_nil No matter how I call assigns, even if I say something like p assigns it errors with: undefined method `template' for nil:NilClass (NoMethodError) So, it seems that I can't do that anymore. Is there an alternative to introspecting what's going on in the controller, or maybe some way of at least running those steps in such a way that I have the integration test stuff back?

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  • Effect of 'myObj = [[[[MyClass alloc] init] autorelease] retain];'?

    - by filipe
    I've just downloaded the Facebook iOS SDK and I noticed that in the sample code that comes with the SDK whenever it creates an instance of the Facebook class it does it like this: _facebook = [[[[Facebook alloc] init] autorelease] retain]; where _facebook is a member variable of the calling object (i.e. not a local variable). Can anyone explain exactly what's the point of autoreleasing and then retaining it?

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  • Binding JBoss to IP Address

    - by Anand
    Hi, I am running a JBoss instance on a linux server I am using the ./run.sh -b This is not working what could be the reason. I am unable to share the error message details as of now will post it when I can, till then any alternatives or solutions ?

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  • Why do encodeXxx methods in UIComponent accept FacesContext parameter?

    - by Roman
    I haven't ever before created custom components in JSF so I've noticed only now that methods like encodeBegin(), encodeEnd() etc accept FacesContext parameter. FacesContext instance can usually be received with FacesContext.getCurrentInstance(). So, I wonder whether these methods have FacesContext parameter just for convenience or some different objects can be passed there (maybe from external resources..). If the latter is possible then could you give an example pls.

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  • Kohana 3 - Getting value from URL

    - by pigfox
    I have log in functionality that will check for a session, if it not there the user will be redirected via Request::instance()-redirect('managers/error/1'); In the error action in the managers controller I can't get the value 1 which represents a specific error msg. How can I capture the value "1" from the url, I'm only using standard routes.

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  • Why is C# statically typed?

    - by terrani
    I am a PHP web programmer who is trying to learn C#. I would like to know why C# requires me to specify the data type when creating a variable. Class classInstance = new Class(); Why do we need to know the data type before a class instance?

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  • Filename of script that instantiates an object

    - by Calvin L
    In PHP, is it possible to get the file name of the script that instantiated an object? For example I have a script called file.php that creates a new instance of class Class. The class has an Error object that, when triggered, returns some error information. I would like to show that file.php triggered the error.

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  • Injection of class with multiple constructors

    - by Jax
    Resolving a class that has multiple constructors with NInject doesn't seem to work. public class Class1 : IClass { public Class1(int param) {...} public Class1(int param2, string param3) { .. } } the following doesn’t seem to work: IClass1 instance = IocContainer.Get<IClass>(With.Parameters.ConstructorArgument(“param”, 1)); The hook in the module is simple, and worked before I added the extra constructor: Bind().To(); Thanks in advance...

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  • Need Help About Using XPathNavigator in C#?

    - by Nano HE
    Hello. My XML file as below. It mixed schema and normal elements. <?xml version="1.0" encoding="utf-8"?> <!-- R1 --> <ax:root xmlns:ax="http://amecn/software/realtime/ax"> <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <xsd:element name="EquipmentConstants"> <xsd:complexType> <xsd:sequence> <xsd:element minOccurs="0" maxOccurs="unbounded" ref="EquipmentConstant" /> </xsd:sequence> </xsd:complexType> <xsd:unique name="id"> <xsd:selector xpath=".//EquipmentConstant" /> <xsd:field xpath="@id" /> </xsd:unique> </xsd:element> ...... ...... </xsd:schema> <EquipmentConstants xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <EquipmentConstant id="0"> <Name>SerialNumber</Name> <Group>SYSTEM</Group> <Data> <Value min="0" max="10000000" scale_factor="0" unit="U_NO_UNITS" permission="NolimitedAndNoChangeable" type="xsd_string" enum="" flag="0">0</Value> </Data> <Description>Serial Number</Description> </EquipmentConstant> ..... ..... </EquipmentConstants> </ax:root> My C# code as below. I want to loop the elements from <EquipmentConstants xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> XPathDocument doc = new XPathDocument("test.xml"); XPathNavigator navigator = doc.CreateNavigator(); navigator.MoveToRoot(); // <?xml version="1.0" encoding="utf-8"?> //navigator.MoveToFirstChild(); // <!-- R1 --> // 1st, I tried to use MoveToChield(), But I failed to move there. navigator.MoveToChild("EquipmentConstants"); // Then, I also tried to use SelectSingleNode(). But I failed too. navigator.SelectSingleNode("ax/EquipmentConstants"); while (navigator.MoveToNext()) { // do something. } Could you please give me some suggestion. Thank you.

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  • Add rel="xx" to jQuery a.link elements

    - by Xavier
    I use a little jQuery script to run a simple music player, but I'd like to add a rel="player" to the links in this jQuery script (the play/stop button for instance). This way I can exclude these rel="player" links from another jQuery script I use, because I don't want it to take the rel="player" elements into account. I reckon this is fair simple but i don't really know how to to it. Here is the jQuery script of the player, if it's ever necessary: http://hyker.be/cv/js/jquery.simpleplayer.min.js

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  • Different ways of accessing configuration parameters from a JAX-WS service

    - by ecerulm
    As far as I know I can access the web.xml <context-param>s by making my class implement ServletContextListener and use the ServletContext.getInitParam(String) to read them, but it´s cumbersome as only one instance of the class will receive the contextInitialized(ServletContextEvent sce) call, so I need to make the ServletContext an static member of the class. What other ways exist of setting conf params at deployment time and what are the recommended ones?

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