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  • javascript singleton question

    - by Shawn
    I just read a few threads on the discussion of singleton design in javascript. I'm 100% new to the Design Pattern stuff but as I see since a Singleton by definition won't have the need to be instantiated, conceptually if it's not to be instantiated, in my opinion it doesn't have to be treated like conventional objects which are created from a blueprint(classes). So my wonder is why not just think of a singleton just as something statically available that is wrapped in some sort of scope and that should be all. From the threads I saw, most of them make a singleton though traditional javascript new function(){} followed by making a pseudo constructor. Well I just think an object literal is enough enough: var singleton = { dothis: function(){}, dothat: function(){} } right? Or anybody got better insights? [update] : Again my point is why don't people just use a simpler way to make singletons in javascript as I showed in the second snippet, if there's an absolute reason please tell me. I'm usually afraid of this kind of situation that I simplify things to much :D

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  • packing fields of a class into a byte array in c#

    - by alex
    Hi all: I am trying to create a fast way to convert c# classes into byte array. I thought of serializing the class directly to a byte array using an example I found: // Convert an object to a byte array private byte[] ObjectToByteArray(Object obj) { if(obj == null) return null; BinaryFormatter bf = new BinaryFormatter(); MemoryStream ms = new MemoryStream(); bf.Serialize(ms, obj); return ms.ToArray(); } But the byte array I got contains some other information that are not related to the fields in the class. I guess it is also converting the Properties of the class. Is there a way to serialize only the fields of the class to a byte array? Thanks

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  • Best way to insert items from a Derived class's constructor into a Base class's private std::vector?

    - by Will
    I have these classes: class Base { ... private: std::vector<X> v; }; class Derived { Derived(X*, int n); } where the constructor of Derived is passed an array of item Xs, which I need to insert into my vector v in the Base class. (X is a smart pointer) Currently I see two ways to do this: 1) Create a function in Base: InsertItem(X*) that will insert an item into the vector. 2) Create a vector in Derived that contains the full list, then get it into Base by moving the entire vector. I dont see any advantages to #2, but was wondering if #1 was a good solution, or if there are better ways to do this. Thanks!

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  • How can I require an attribute on a class definition?

    - by spoulson
    Is there a way to enforce a compile requirement for certain attributes on a class or interface implementation? For example, let's say my application uses a series of static classes that contain const int resource values. I'd like to decorate the class in a Description attribute to describe its contents. In concept, I'd like to apply this attribute requirement to an interface, then each static class would implement it with its required Description. I could write a run-time check or a unit test to check compliance. But really a compile-time check would be best. Is there such a thing?

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  • Is the a pattern for iterating over lists held by a class (dynamicly typed OO languages)

    - by Roman A. Taycher
    If I have a class that holds one or several lists is it better to allow other classes to fetch those lists(with a getter) or to implement a doXList/eachXList type method for that list that take a function and call that function on each element of the list contained by that object. I wrote a program that did a ton of this and I hated passing around all these lists sometimes with method in class a calling method in class B to return lists contained in class C, B contains a C or multiple C's (note question is about dynamically typed OO languages languages like ruby or smalltalk) ex. (that came up in my program) on a Person class containing scheduling preferences and a scheduler class needing to access them.

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  • Java CRTP: Works for container but not for methods?

    - by Daniel
    I have a baseclass with a protected static ArrayList. I want to have a seperate ArrayList for each kind of subclass that extends this baseclass. This is when I applied CRTP: public class BaseExample<T> { protected static ArrayList<Integer> data = new ArrayList<Integer>(); } This works just fine. However, when I try to implement the following static method in the same base class, it doesn't adhere to CRTP: public static void clear() { data.clear(); } For example: class SubExample extends BaseExample<SubExample> { // insertion methods accessing 'data' field // these work fine :) } SubExample.clear(); // does not seem to clear data container Do I need to somehow explicitly specify T in my baseclass clear method? Note: These are all pure static classes.

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  • mysql eliminate responses under certain condition with join

    - by Dustin
    Forgive me if this is an easy question. I teach classes and want to be able to select those students who have taken one class, but not another class. I have two tables: lessons_slots which is the table for every class such as: -------------------- -ID name slots- -1 basics 10 - -2 advanced 10 - -3 basics 10 - --------------------- The other table is class_roll, which holds enrollment info, such as: -------------------- -sID classid firstname lastname- -1 1 Jo Schmo -2 1 Person Two ... -13 2 Jo Schmo --------------------- What I want to do, I select everyone who has not had the advanced class (for example). I've tried doing SELECT * FROM lessons_slots LEFT JOIN class_roll ON lessons_slots.ID = class_roll.classid WHERE lessons_slots.name != 'advanced' But that doesn't work. Any ideas?

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  • How to set variable before callback is called?

    - by user1995327
    I'm trying to design a webpage... I have a function that I call get all info needed for an idividuals home page. A snippet of the codes is: exports.getHomePageData = function(userId, cb) { var pageData = {}; pageData.userFullName = dbUtil.findNameByUserId(userId, function(err){ if (err) cb(err); }); pageData.classes = dbUtil.findUserClassesByUserId(userId, function(err){ if (err) cb(err); }); cb(pageData); } The problem I'm having is the cb(pageData) is being called before I even finish setting the elements. I've seen that people use the async library to solve this but I was wondering if there was any other way for me to do it without needing more modules... Thanks!

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  • Spring & Hibernate EJB Events

    - by Miguel Ping
    Is it possible to define a spring-managed EJB3 hibernate listener? I have this definition in my persistence.xml: <properties> <property name="hibernate.ejb.interceptor" value="my.class.HibernateAuditInterceptor" /> <property name="hibernate.ejb.event.post-update" value="my.class.HibernateAuditTrailEventListener" /> </properties> But I would like to manage HibernateAuditInterceptor and HibernateAuditTrailEventListener with spring, so I can do some bean injection (ex: session-scoped bean) within these classes. Is this possible?

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  • Visual Studio: Link executable

    - by smerlin
    Lets say I have: a static library project called "LIB" a application project called "LIBAPP" a application project called "APP" a application project called "APPTEST" When i add "LIB" to LIBAPP Project Dependencies, Visual Studio automatically links "LIBAPP" against LIB. But when i add APP to APPTEST Project Dependencies, it doesnt. Since i am doing unit tests of APP's classes in APPTEST, i have to link against APP, therefore i am currently manually linking against all *.obj files of APP (hundreds...) Since i have to change the link targets of APPTEST everytime i add or remove a *.cpp file from APP, this isnt a nice solution. So is there a way to force Visual Studio to do this for me automatically, like it does when adding a static library Project Dependency ?

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  • Using a backwards relation (i.e FOO_set) for ModelChoiceField in Django

    - by Bwmat
    I have a model called Movie, which has a ManyToManyField called director to a model called Person, and I'm trying to create a form with ModelChoiceField like so: class MovieSearchForm(forms.Form): producer = forms.ModelChoiceField(label='Produced by', queryset=movies.models.Person.producer_set, required=False) but this seems to be failing to compile (I'm getting a ViewDoesNotExist exception for the view that uses the form, but it goes away if I just replace the queryset with all the person objects), I'm guessing because '.producer_set' is being evaluated too 'early'. How can I get this work? here are the relevant parts of the movie/person classes: class Person(models.Model): name = models.CharField(max_length=100) class Movie(models.Model): ... producer = models.ForeignKey(Person, related_name="producers") director = models.ForeignKey(Person, related_name="directors") What I'm trying to do is get ever Person who is used in the producer field of some Movie.

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  • how to selfhost wcf without iis

    - by dotnetcoder
    Reading up on WCF we have self hosting option available , one limitation here is we have to manage the host process lifecycle ourselves. What I am exploring here is to run the service without IIS and do a self hosting. Few things come to mind - How will request management work here. In case of IIS it manages the request and give control to dotnet on a particular thread. In absence of IIS do we need to write code ourselves to manage incoming requests ( say on a tcp port ) or WCF provides some classes to manage request and spawn threads to process each thread. I am aware that in case of self hosting this needs to be a windows service. In case of self hosting how can me tap on the number of simultaneous requests on the sever , it can be managed by limiting the thread pool ? or we can configure this via wcf ? Thanks dc

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  • Can i access outer class objects in inner class

    - by Shantanu Gupta
    I have three classes like this. class A { public class innerB { //Do something } public class innerC { //trying to access objB here directly or indirectly over here. //I dont have to create an object of innerB, but to access the object created by A //i.e. innerB objInnerB = objB; //not like this innerB objInnerB= new innerB(); } public innerB objB{get;set;} } I want to access the object of class B in Class C that is created by class A. Is it possible somehow to make changes on object of Class A in Class C. Can i get Class A's object by creating event or anyhow.

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  • Multiple loadmovie() ends up with multiple videos played at the same time!

    - by David
    Hi, i'm using loadmovie() to load a youtube video player inside my flash website but when i load another video the old one doesn't stop, so i tried unloadmovie to destroy it but it seems that i did a mistake in my code This is how the code looks to stop the old one an load the new: vloader.unloadMovie(); vloader.loadMovie("http://www.youtube.com/v/Alw5hs0chj0&hl=fr&fs=1hJ-mPcGtC"); How to do that? please don't suggest me to use other objects or classes, i only want to edit that code. Note: I have an empty CLIP called "vloader" where i load the video player. Thank you

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  • How to sort a list by the 2nd tuple element in python and C#

    - by user350468
    I had a list of tuples where every tuple consists of two integers and I wanted to sort by the 2nd integer. After looking in the python help I got this: sorted(myList, key=lambda x: x[1]) which is great. My question is, is there an equally succinct way of doing this in C# (the language I have to work in)? I know the obvious answer involving creating classes and specifying an anonymous delegate for the whole compare step but perhaps there is a linq oriented way as well. Thanks in advance for any suggestions.

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  • Python metaprogramming help

    - by Timmy
    im looking into mongoengine, and i wanted to make a class an "EmbeddedDocument" dynamically, so i do this def custom(cls): cls = type( cls.__name__, (EmbeddedDocument,), cls.__dict__.copy() ) cls.a = FloatField(required=True) cls.b = FloatField(required=True) return cls A = custom( A ) and tried it on some classes, but its not doing some of the base class's init or sumthing in BaseDocument def __init__(self, **values): self._data = {} # Assign initial values to instance for attr_name, attr_value in self._fields.items(): if attr_name in values: setattr(self, attr_name, values.pop(attr_name)) else: # Use default value if present value = getattr(self, attr_name, None) setattr(self, attr_name, value) but this never gets used, thus never setting ._data, and giving me errors. how do i do this?

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  • Using a proxy for NSURLConnection

    - by SideSwipe
    Is there any way to get the content of a webfile (namely a .html Document) using a proxy, which is not defined in the system settings? I know that NSURLConnection is the right way to download a web file into a variable and not into a file (for which we should use NSURLDownload), but I don't find a way to use a proxy for it. Are there some unofficial APIs, Libraries or Classes or such I could use for what I want to do? I'm not that pro in Mac Programming, so I'm searching for something more or less simple. SideSwipe

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  • Auto wiring of Property does not work for me

    - by Xabatcha
    Hi All, In my Asp.Net project I wanna use Property Auto-wiring, e.g. for my ILogger. Basically I placed Property into my base classes. One for Page, one for UserControl. Like below. public class UserControlBase : UserControl { public ILogger CLogger { get; set; } .... } However when calling in inherited control, logger is null. I checked the container and it'a definitely set. Below is setting which is called from Global.asax. public static void SetupForIoC() { Debug.WriteLine("SetupForIoC"); ObjectFactory.Initialize(x => { x.FillAllPropertiesOfType<ILogger>().TheDefaultIsConcreteType<EntLibLogger>().AsSingletons(); x.FillAllPropertiesOfType<ISiteService>().TheDefaultIsConcreteType<SiteService>().AsSingletons(); }); Debug.WriteLine(ObjectFactory.WhatDoIHave()); } Thanks for any advice, tip? X.

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  • What should happen when a reference is deleted?

    - by Apeksha
    I have a vb.net 3.5 application which references a dll (abc.dll, also in .net 3.5) This dll is accessed by the application from time to time. If at anytime during execution, if I delete the dll, I expect the application to throw an error the next time it tries to use a class from the dll. But, this is not the behaviour I see. If I delete the dll before startup, the application throws an error at startup. But not when the dll is deleted after startup. Is this the standard behaviour, or am I doing something wrong? Can I get the app to throw an error if the dll is not found when it tries to use its classes? Thanks in advance.

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  • How to set order of appearance for fields when using Html.EditorFor in MVC 2?

    - by Anrie
    I have the following classes in my Model: public abstract class Entity : IEntity { [ScaffoldColumn(false)] public int Id { get; set; } [Required,StringLength(500)] public string Name { get; set; } } and public class Model : SortableEntity { [Required] public ModelType Type { get; set; } [ListRequired] public List<Producer> Producers { get; set; } public List<PrintArea> PrintAreas { get; set; } public List<Color> Colors { get; set; } } To display the "Model" class in the view I simply call Html.EditorFor(model=model), but the "Name" property of the base class is rendered last, which is not the desired behaviour. Is it possible to influenece on the order of displayed fields somehow?

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  • Navigation properties not set when using ADO.NET Mocking Context Generator

    - by olenak
    I am using ADO.NET Mocking Context Generator plugin for my Entity Framework model. I have not started on using mocks yet, just trying to fix generated entity and context classes to make application run as before without exceptions. I've already fixed T4 template to support SaveChanges method. Now I've got another problem: when I try to access any navigation property it is set to null. All the primitive fields inherited from DB table are set and correct. So what I am doing is the following using (var context = MyContext()) { var order = context.Orders.Where(p => p.Id == 7); var product = order.Products; } in this case product is set to null. But that was not a case while using default code generator, it used to return real product object. Thanks ahead for any suggestions!

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  • External GUI/Helper Library for Visual C++?

    - by Psychic
    I am looking for some kind of library, either open source or bought in, that provides advanced GUI components, helper functions & classes etc. It needs to be something that integrates relatively easily into Visual Studio, and should be based around C++ and Windows. Cross platform isn't needed, and can somtimes make things a little more complex and restricted than single platform, but it is still acceptable. It also needs to be up-to-date and active. There appears to be a number of 'retired' libraries that offer little or no support, so these would not be suitable, as I'm going to need help every now and then! It also needs good documentation. I know about wxWidgets but I'm wondering what other alternatives there are? At first glance, wxWidgets doesn't strike me as what I want/need, especially in the GUI area where the visual components seem striking similar to the stock components. I want more custimization! Is there much out there that meets these requirements?

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  • What comes first in Ruby's object model?

    - by Timothy
    I've been reading Metaprogramming Ruby and the object model like the chicken or egg dilemma. In Ruby 1.8, the Object class is an instance of Class. Module's superclass is Object and is an instance of Class. Class' superclass is Module, and it is an instance of Class (self-referential). Say class SomeClass; end is defined somewhere; SomeClass is an instance of Class, however its superclass is Object. Why does an instance of Class have Object as the superclass instead of nil? Also, if Object is to exist, then Class has to exist, but then Module has to exist, but for Module to exist Object has to exist. How are these classes created?

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  • Forcing GWT to assume List is implemented as ArrayList

    - by joecks
    For some reason I'm stucked with model classes using List as Collection Type and I would like to use the model on the client side. However GWT of course fails serializing java.util.List. However all implementations of List in this model are based on ArrayList. So is it possible to tell GWT to assume List is ArrayList? Edit GWT fails on compile time, since a possible candidate for List is also java.util.Collections.SingeltonList - which can not be compiled. I'm using GWT 2.1 and Java 1.6 .

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  • how to get an instance of an XMLEventAllocator?

    - by kostja
    I am trying to follow the recommended way of parsing XML with StAX using sun's Cursor-to-Event Example for Java EE 5. You are supposed to traverse the XML via the Cursor API and allocate an XMLEventusing an XMLEventAllocator when necessary. Awkwardly, sun's own example does not compile (at least not with JDK 1.6, even with 1.5 code compliance). The example tries to instantiate an allocator via new, but the according implementation classes in the JDK are not accessible externally. After reading the JavaDocs and searching the web I have found literally nothing. One could implement the XMLEventAllocator interface from scratch, but it seems really wrong, when there are perfectly good implementations in the JDK, besides not being an expert in StAX makes it difficult to get it right.

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