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• How to persist every new entity?

  - by simpatico

  I expect every instantiated entity to correspond to a tuple (& co) in the database. In the examples I see around, one always instantiates the entity (via a constructor) and then calls persist with that entity. I find this error-prone, and was wondering if it wasn't possible to have every instantiated entity automatically managed/persisted/reflected to the database (at least intended to). This also seems to prevent me from persisting instance variable entities. I.e. I've an entity which instantiates another (entities it has an association with) in its constructor.

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• Using Boost statechart, how can I transition to a state unconditionally?

  - by nickb

  I have a state A that I would like to transition to its next state B unconditionally, once the constructor of A has completed. Is this possible? I tried posting an event from the constructor, which does not work, even though it compiles. Thanks. Edit: Here is what I've tried so far: struct A : sc::simple_state< A, Active > { public: typedef sc::custom_reaction< EventDoneA > reactions; A() { std::cout << "Inside of A()" << std::endl; post_event( EventDoneA() ); } sc::result react( const EventDoneA & ) { return transit< B >(); } }; This yields the following runtime assertion failure: Assertion failed: get_pointer( pContext_ ) != 0, file /includ e/boost/statechart/simple_state.hpp, line 459

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• Returning and instance of a Class given its .class (MyClass.class)

  - by jax

  I have an enum that will hold my algorithms. I cannot instantiate these classes because I need the application context which is only available once the application has started. I want to load the class at runtime when I choose by calling getAlgorithm(Context cnx). How do I easily instantiate a class at runtime given its .class (and my constructor takes arguments)? All my classes are subclasses of Algorithm. public enum AlgorithmTypes { ALL_FROM_9_AND_LAST_FROM_10_ID(AlgorithmFactory.AlgorithmAllFrom9AndLastFrom10Impl.class), ALL_FROM_9_AND_LAST_FROM_10_CURRENCY_ID(AlgorithmFactory.AlgorithmAllFrom9AndLastFrom10Impl.class), DIVIDE_BY_9_LESS_THAN_100(AlgorithmFactory.AlgorithmAllFrom9AndLastFrom10Impl.class), TABLES_BEYOND_5_BY_5(AlgorithmFactory.AlgorithmAllFrom9AndLastFrom10Impl.class); private Class<? extends Algorithm> algorithm; AlgorithmTypes(Class<? extends Algorithm> c) { algorithm = c; } public Algorithm getAlgorithm(Context cnx) { return //needs to return the current algoriths constructor which takes the Context Algorithm(Context cnx); } }

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• Confusion over C++ new operator and classes

  - by Nils

  Hi all I created a simple class in C++ which has a private dynamic array. In the constructor I initialize the array using new and in the destructor I free it using delete. When I instantiate the class using Class a = Class(..); it works as expected, however it seems I cannot instantiate it using the new operator (Like Class *a = new Class(..);), I always get a segmentation fault. What I don't understand is when I should use new to instantiate a class and when just call the constructor or should it be possible to instantiate a class either with new or by just calling the constructor. float** A = new float*[3]; for (int i=0; i<3; i++) { A[i] = new float[3]; } A[0][0] = 3; A[0][1] = 3; A[0][2] = 4; A[1][0] = 5; A[1][1] = 6; A[1][2] = 7; A[2][0] = 1; A[2][1] = 2; A[2][2] = 3; Matrix *M = new Matrix(A, 3, 3); delete[] A; delete M; Below the class definition.. class Matrix { private: int width; int height; int stride; float* elements; public: Matrix(float** a, int n, int m); ~Matrix(); }; Matrix::Matrix(float** a, int n, int m) { // n: num rows // m: elem per rows elements = new float[n*m]; for (int i=0; i<n; i++) { for (int j=0; j<m; j++) { elements[i*n + j] = a[n][m]; } } } Matrix::~Matrix() { delete[] elements; }

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• How to avoid double construction of proxy with DynamicProxy::CreateClassProxyWithTarget?

  - by Belvasis

  I am decorating an existing object using the CreateClassProxyWithTarget method. However, the constructor and therefore, initialization code, is being called twice. I already have a "constructed" instance (the target). I understand why this happens, but is there a way to avoid it, other than using an empty constructor? Edit: Here is some code: First the proxy creation: public static T Create<T>(T i_pEntity) where T : class { object pResult = m_pGenerator.CreateClassProxyWithTarget(typeof(T), new[] { typeof(IEditableObject), typeof(INotifyPropertyChanged) , typeof(IMarkerInterface), typeof(IDataErrorInfo) }, i_pEntity, ProxyGenerationOptions.Default, new BindingEntityInterceptor<T>(i_pEntity)); return (T)pResult; } I use this for example with an object of the following class: public class KatalogBase : AuditableBaseEntity { public KatalogBase() { Values = new HashedSet<Values>(); Attributes = new HashedSet<Attributes>(); } ... } If i now call BindingFactory.Create(someKatalogBaseObject); the Values and Attributes properties are beeing initialized again.

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• Creating immutable objects from javabean

  - by redzedi

  Hi All, I am involved in this project where we are building on good bit of legacy code. I have a particular situation about one big java bean object which has to be transferred over wire. So my first thought was to make it immutable and serializable to do the trick .At this point I am faced with a few difficult choices :- 1 Ideally I want some way to automatically generate an immutable, serializable version of this class. I dont have the scope to refactor or alter this class in any way and i would really really hate to have to copy paste the class with a different name ?? 2 Assuming that i gave up on 1 i.e i actually chose to duplicate code of the HUGE javabean class , i still will be in the unsavoury situation of having to write a constructor with some 20-25 parameters to make this class immutable. what is a better way to make a class immutable other than constructor injection ?? Thanks and Regards,

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• Fast check if an object will be successfully instantiated in PHP?

  - by Gremo

  How can I check if an object will be successfully instantiated with the given argument, without actually creating the instance? Actually I'm only checking (didn't tested this code, but should work fine...) the number of required parameters, ignoring types: // Filter definition and arguments as per configuration $filter = $container->getDefinition($serviceId); $args = $activeFilters[$filterName]; // Check number of required arguments vs arguments in config $constructor = $reflector->getConstructor(); $numRequired = $constructor->getNumberOfRequiredParameters(); $numSpecified = is_array($args) ? count($args) : 1; if($numRequired < $numSpecified) { throw new InvalidFilterDefinitionException( $serviceId, $numRequired, $numSpecified ); }

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• i need help to designe code in c++

  - by user344987

  ) Design and implement a Graph data structure. Use adjacency matrix to implement the unweighted graph edges. The Graph must support the following operations: 1.Constructor 2.Destructor 3.Copy constructor 4.A function to add an edge between two nodes in the graph 5.A display function that outputs all the edges of the graph 6.A function edge that accepts two nodes, the function returns true if there is an edge between the passed nodes, and returns false otherwise. B.(100 points) Depth first search and Breadth first search functions. C.(100 points) A function to output a spanning tree of the graph, use any algorithm you find appropriate, also, make the necessary changes on the data structure in A to implement your algorithm.

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• Constructors + Dependency Injection

  - by Sunny

  If I am writing up a class with more than 1 constructor parameter like: class A{ public A(Dependency1 d1, Dependency2 d2, ...){} } I usually create a "argument holder"-type of class like: class AArgs{ public Dependency1 d1 { get; private set; } public Dependency2 d2 { get; private set; } ... } and then: class A{ public A(AArgs args){} } Typically, using a DI-container I can configure the constructor for dependencies & resolve them & so there is minimum impact when the constructors need to change. Is this considered an anti-pattern and/or any arguments against doing this?

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• Where to register for C# events?

  - by themaninthesuitcase

  I am currently transitioning from VB to C# and am having some issues with regards to registering my interest in an event. When using VB it was simply a case of specifying that a method Handles and event, often this was generated by using the object events list. While I can easily use the Class.event += delegate in C# I am unsure where the best place is to place the code to do this. Am I best placing it inside of the InitializeComponent() as per the generated code (say if you select the event in the from designer) or should I place it inside the constructor for better readability/maintenance. If inside the constructor, should it be before or after the call to InitializeComponent()?

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• Why can't I enforce derived classes to have parameterless constructors?

  - by FrisbeeBen

  I am trying to do the following: public class foo<T> where T : bar, new() { public foo() { _t = new T(); } private T _t; } public abstract class bar { public abstract void someMethod(); // Some implementation } public class baz : bar { public overide someMethod(){//Implementation} } And I am attempting to use it as follows: foo<baz> fooObject = new foo<baz>(); And I get an error explaining that 'T' must be a non-abstract type with a public parameterless constructor in order to use it as parameter 'T' in the generic type or method. I fully understand why this must be, and also understand that I could pass a pre-initialized object of type 'T' in as a constructor argument to avoid having to 'new' it, but is there any way around this? any way to enforce classes that derive from 'bar' to supply parameterless constructors?

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• how to create a dynamic class at runtime in Java

  - by Mrityunjay

  hi, is it possible to create a new java file from existing java file after changing some of its attributes at runtime?? Suppose i have a java file pubic class Student{ private int rollNo; private String name; // getters and setters // constructor } is it possible to create something like this, provided that rollNo is key element for the table.. public class Student { private StudentKey key; private String name; //getters and setters //constructor } public class StudentKey { private int rollNo; // getters and setters // construcotors } please help..

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• How to access the service instance from host object in WCF?

  - by user1048677

  I am trying to incarnate some sort of ad hoc WCF service. I already managed to launch it and make it call its own web methods as some other guy's methods. The issue that I am facing is instance management. I have set [ServiceBehavior(InstanceContextMode = InstanceContextMode.Single)] so it now has a global instance with the same properties for all clients. But besides that I need it to call other services of its kind while listening to incoming requests from clients (similar crazy services). While debugging I noticed that the ServiceHost's constructor calls the constructor of the service class. So, I assumed it has access to the global instance of this class and I need to find a way to call methods of this instance. Please don't ask what I have been smoking, I just have to make it ad hoc.

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• How can Java assignment be made to point to an object instead of making a copy?

  - by Matthew Piziak

  In a class, I have: private Foo bar; public Constructor(Foo bar) { this.bar = bar; } Instead of creating a copy of bar from the object provided in the parameter, is it possible to include a pointer to bar in the constructor such that changing the original bar changes the field in this object? Another way of putting it: int x = 7; int y = x; x = 9; System.out.print(y); //Prints 7. It is possible to set it up so that printing y prints 9 instead of 7?

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• Django GenericRelation doesn't save related object's id - is this a bug or am I doing it wrong?

  - by pinkeen

  I have a model with a generic relation (call it A), when creating an instance of this object I pass an instance of another model (call it B) as the initializer of the content_object field (via kwargs of the constructor). If I don't save B before creating A then when saving A the content_object_id is saved to the db as NULL. If I save B before passing it to the constructor of A then everything's allright. It's not logical. I assumed that the ID of the related object (B) is fetched when doing A.save() and it should throw some kind of an exception if B isn't saved yet but it just fails silently. I don't like the current solution (saving B beforhand) because we don't know yet if I will be always willing to keep the object, not just scrap it, and there are performance considerations - what if I will add some another data and save it once more shortly after. class BaseNodeData(models.Model): ... extnodedata_content_type = models.ForeignKey(ContentType, null=True) extnodedata_object_id = models.PositiveIntegerField(null=True) extnodedata = generic.GenericForeignKey(ct_field='extnodedata_content_type', fk_field='extnodedata_object_id') class MarkupNodeData(models.Model): raw_content = models.TextField() Suppose we do: markup = MarkupNodeData(raw_content='...') base = BaseNodeData(..., extnodedata=markup) markup.save() base.save() # both records are inserted to the DB but base is stored with extnodedata_object_id=NULL markup = MarkupNodeData(raw_content='...') base = BaseNodeData(..., extnodedata=markup) base.save() markup.save() # no exception is thrown and everything is the same as above markup = MarkupNodeData(raw_content='...') markup.save() base = BaseNodeData(..., extnodedata=markup) base.save() # this works as expected Of course I can do it this way, but it doesn't change anything: base = BaseNodeData(...) base.extnodedata = markup My question is - is this a bug in django which I should report or maybe I'm doing something wrong. Docs on GenericRelations aren't exactly verbose.

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• as3 this.graphics calls do nothing

  - by zzz

  class A: [SWF(width='800',height='600',frameRate='24')] public class A extends MovieClip { private var b:B; public function A(){ super(); b = new B(); addChild(b); addEventListener(Event.ENTER_FRAME, update); } private function update(e:Event):void { b.draw(); } } class B: public class B extends MovieClip { public function draw():void { //! following code works well if put in constructor, but not here this.graphics.beginFill(0xff0000); this.graphics.drawCircle(200,200,50); } } this.graphics calls do nothing in draw method, but work fine inside B`s constructor, what i am doing wrong ?

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• Can a static member be overloaded?

  - by Daniel

  type A() = static member B() = () static member B(x) = B() //ERROR: The value or constructor 'B' is not defined

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• Javascript: Inherit method from base class and return the subclass's private variable

  - by marisbest2

  I have the following BaseClass defined: function BaseClass (arg1,arg2,arg3) { //constructor code here then - var privateVar = 7500; this.getPrivateVar = function() { return privateVar; }; } I want to have the following subclass which allows changing privateVar like so: function SubClass (arg1,arg2,arg3,privateVar) { //constructor code here then - var privateVar = privateVar; } SubClass.prototype = new BaseClass(); Now I want SubClass to inherit the getPrivateVar method. However, when I try this, it always returns 7500 which is the value in the BaseClass and not the value of privateVar. In other words, is it possible to inherit a BaseClass's public methods but have any references in them refer to the SubClass's properties? And how would I do that?

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• Changing the value of a macro at run time

  - by BrandiNo

  I'm working in Visual Studio 2010, using C++ code. What I'm trying to do is change the value of a preprocessor directive during run time, not sure if it's possible but i've tried this.. somefile.h static int mValue = 0; #define POO = mValue; ... #if POO 0 //define class methods #else //define class methods differently } main.cpp main() { //Code calls constructor and methods allowed when POO is 0 //Code increments mValue //Code calls constructor and methods allowed when POO is 1 } How can POO be changed so that class objects uses a different implementation of other methods? Or if it's not possible, what's a another approach to this?

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• Create Object using ObjectBuilder

  - by dhinesh

  Want to create objects using ObjectBuilder or ObjectBuilder2. I do not want to use StructureMap I was able to create the object having parameterless constructor using the code mentioned below. public class ObjectFactory : BuilderBase<BuilderStage> { public static T BuildUp<T>() { var builder = new Builder(); var locator = new Locator { { typeof(ILifetimeContainer), new LifetimeContainer() } }; var buildUp = builder.BuildUp<T>(locator, null, null); return buildUp; } for creating object of customer you just call ObjectFactory.BuildUp<Customer> However this creates object of class which has no parameters, however I need to create object which are having constructor with parameters.

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• Daisy Chain a VNC

  - by mastercork889

  Part 1. Theoretically, would daisy chaining a VNC work? EG, If I wanted to VNC into a specific computer on a different network could I VNC into a computer onto that network and ultimately get into the computer I need? So computers A, B, C, D, and E, are all on different networks from one another. I'm at A, could I VNC into B, then C, then D, then E. I understand that I can just VNC into E, but this question is a theoretical question. Part 2. Could I do a sub-looped daisy chain with VNCs? EG, A B C D C B E? Could that theoretically work, or would it screw up somewhere along the trail?

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• usb vs firewire for connecting two RAID 0 disks

  - by Arne

  I have a 2TB and a 4TB RAID 0 external drives (both have two physical hard drives in them). Both have a FW800, FW400, and USB port. My MacBook Pro has one FW800 port and two USB ports. I want to copy data from the 4TB drive to the 2TB drive. Is it better to A - connect both directly to the laptop, one with USB and one with FW800 or B - connect the 4TB drive to laptop with FW800 and the 2TB drive to the 4TB drive using a FW400 cable? Anyone have problems daisy-chaining RAID 0 disks using FW? Thanks!

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• Avoiding double NAT with PPPoA connection

  - by user498429

  I've got an ASUS RT-N56U wending its way to me and have been thinking about how to set this up on my home network. I currently have a Netgear DG634g V5 and was hoping to use this device as a modem only, with everything else being done by the router. Problem is, my ISP uses PPPoA and the asus seems only to support PPPoE. I'm aware that a double NAT configuration should be avoided and I've seen some instructions here: http://www.tomshardware.co.uk/forum/33700-17-ultimate-modem-router-setup-thread Specifically, I was going to follow the guidance in the section entitled "Chaining Two Networks Together In a Cascading Fashion (Modem handles PPPoA)". That seems like it could work. However, is this a double NAT configuration or even a good way to do it? Would UPnP still work? The other option, I understand, is to buy the Draytek Vigor 120 but I'd ideally like to avoid the cost of that if its not necessary.

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• Changing encryption settings for Microsoft Office 2010/2013

  - by iridescent

  Although there are Office 2013 settings to change how encryption is performed, when you encrypt Open XML Format files (.docx, .xslx, .pptx, and so on) the default values — AES (Advanced Encryption Standard), 128-bit key length, SHA1, and CBC (cipher block chaining) — provide strong encryption and should be fine for most organizations. Quoted from http://technet.microsoft.com/en-us/library/cc179125.aspx . I can't figure out where is the setting to change how encryption is performed. Is there any possible to change the encryption algorithm being used instead of the default AES-128 ? Thanks.

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• is it possible to use multiple proxies for different target websites?

  - by fduff

  Typically I'd like to know if it's possible to have a setup where it maps some IPs with a particular proxy and other IPs using another proxy? Proxy Chaining isn't really what I'm looking for (well I don't think it is) because each address could be resolved with or without a proxy but their content may not be accessible without the right proxy. This setup could be part of home network, so that the relevant proxy s/w could be installed and setup on a Linux box for ex. Ex: website-A via proxy-1 website-B via proxy-2 all others via no-proxy

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