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• Are document-oriented databases any more suitable than relational ones for persisting objects?

  - by Owen Fraser-Green

  In terms of database usage, the last decade was the age of the ORM with hundreds competing to persist our object graphs in plain old-fashioned RMDBS. Now we seem to be witnessing the coming of age of document-oriented databases. These databases are highly optimized for schema-free documents but are also very attractive for their ability to scale out and query a cluster in parallel. Document-oriented databases also hold a couple of advantages over RDBMS's for persisting data models in object-oriented designs. As the tables are schema-free, one can store objects belonging to different classes in an inheritance hierarchy side-by-side. Also, as the domain model changes, so long as the code can cope with getting back objects from an old version of the domain classes, one can avoid having to migrate the whole database at every change. On the other hand, the performance benefits of document-oriented databases mainly appear to come about when storing deeper documents. In object-oriented terms, classes which are composed of other classes, for example, a blog post and its comments. In most of the examples of this I can come up with though, such as the blog one, the gain in read access would appear to be offset by the penalty in having to write the whole blog post "document" every time a new comment is added. It looks to me as though document-oriented databases can bring significant benefits to object-oriented systems if one takes extreme care to organize the objects in deep graphs optimized for the way the data will be read and written but this means knowing the use cases up front. In the real world, we often don't know until we actually have a live implementation we can profile. So is the case of relational vs. document-oriented databases one of swings and roundabouts? I'm interested in people's opinions and advice, in particular if anyone has built any significant applications on a document-oriented database.

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• Free utility which runs in Linux to create a UML class diagram from Java source files

  - by DeletedAccount

  I prefer to jot down UML-diagrams on paper and then implement them using Java. It would be nice to have a utility which could create UML-diagrams for me which I may share on-line and include in the digital documentation. In other words: I want to create UML diagrams from Java source code. The utility must be able to: Run in Linux. Handle Generics, i.e show List<Foo correctly in parameters and return type. Show class inheritance and interface implementations. It's nice if the utility is able to: Run in Windows and Mac OS X. Display enums in some nice manner. Generate output in a diagram format which I may modify using some other utility. Run from the command line. Restrict the UML generation to a set of packages which I may specify. Handle classes/interfaces which are not part of my source code. It could include the first class/interface which is external in the UML diagram. Perhaps in another color to indicate it being a library/framework created by someone else. Focuses on this task and doesn't try to solve the whole issue of documentation.

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• In Java it seems Public constructors are always a bad coding practice

  - by Adam Gent

  This maybe a controversial question and may not be suited for this forum (so I will not be insulted if you choose to close this question). It seems given the current capabilities of Java there is no reason to make constructors public ... ever. Friendly, private, protected are OK but public no. It seems that its almost always a better idea to provide a public static method for creating objects. Every Java Bean serialization technology (JAXB, Jackson, Spring etc...) can call a protected or private no-arg constructor. My questions are: I have never seen this practice decreed or written down anywhere? Maybe Bloch mentions it but I don't own is book. Is there a use case other than perhaps not being super DRY that I missed? EDIT: I explain why static methods are better. .1. For one you get better type inference. For example See Guava's http://code.google.com/p/guava-libraries/wiki/CollectionUtilitiesExplained .2. As a designer of the class you can later change what is returned with a static method. .3. Dealing with constructor inheritance is painful especially if you have to pre-calculate something.

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• How to create instances of a class from a static method?

  - by Pierre

  Hello. Here is my problem. I have created a pretty heavy readonly class making many database calls with a static "factory" method. The goal of this method is to avoid killing the database by looking in a pool of already-created objects if an identical instance of the same object (same type, same init parameters) already exists. If something was found, the method will just return it. No problem. But if not, how may I create an instance of the object, in a way that works with inheritance? >>> class A(Object): >>> @classmethod >>> def get_cached_obj(self, some_identifier): >>> # Should do something like `return A(idenfier)`, but in a way that works >>> class B(A): >>> pass >>> A.get_cached_obj('foo') # Should do the same as A('foo') >>> A().get_cached_obj('foo') # Should do the same as A('foo') >>> B.get_cached_obj('bar') # Should do the same as B('bar') >>> B().get_cached_obj('bar') # Should do the same as B('bar') Thanks.

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• WCF ServiceContract and svcutil issue

  - by Valko

  Hi, I have a public interface auto-generated bu svcutil: [System.ServiceModel.ServiceContractAttribute(Namespace="...", ConfigurationName="...")] public interface MyInterface Then I have asmx web service inheriting it and working fine. I am trying ot convert it to WCF but when I instrument the service (in asmx.cs code behind) with ServiceContract: [ServiceContract(Namespace = "...")] public class MyService : MyInterface Also I have cerated .svc file and added the system.serviceModel setting in the config file. The goal is to migrate the asmx service to WCF service. I've got this error: The service class of type MyService both defines a ServiceContract and inherits a ServiceContract from type MyInterface. Contract inheritance can only be used among interface types. If a class is marked with ServiceContractAttribute, it must be the only type in the hierarchy with ServiceContractAttribute. The asmx service is still working fine. Only the .svc is giving me issues. My question is how to fix that. MyInterface is an interface so I do not see what the problem is and why I've got the error anyway. Note I do not want to change MyInterface, because it is autogenerated from svcutil from my wsdl schema and I do not want this interface to be edited manually. The whole idea is to have the service types automatically genereted from WSDL and to save my team development efforts with manual editing. Any help is appreciated.

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• WM_NOTIFY and superclass chaining issue in Win32

  - by DasMonkeyman

  For reference I'm using the window superclass method outlined in this article. The specific issue occurs if I want to handle WM_NOTIFY messages (i.e. for custom drawing) from the base control in the superclass I either need to reflect them back from the parent window or set my own window as the parent (passed inside CREATESTRUCT for WM_(NC)CREATE to the base class). This method works fine if I have a single superclass. If I superclass my superclass then I run into a problem. Now 3 WindowProcs are operating in the same HWND, and when I reflect WM_NOTIFY messages (or have them sent to myself from the parent trick above) they always go to the outermost (most derived) WindowProc. I have no way to tell if they're messages intended for the inner superclass (base messages are supposed to go to the first superclass) or messages intended for the outer superclass (messages from the inner superclass are intended for the outer superclass). These messages are indistinguishable because they all come from the same HWND with the same control ID. Is there any way to resolve this without creating a new window to encapsulate each level of inheritance? Sorry about the wall of text. It's a difficult concept to explain. Here's a diagram. single superclass: SuperA::WindowProc() - Base::WindowProc()---\ ^--------WM_NOTIFY(Base)--------/ superclass of a superclass: SuperB::WindowProc() - SuperA::WindowProc() - Base::WindowProc()---\ ^--------WM_NOTIFY(Base)--------+-----------------------/ ^--------WM_NOTIFY(A)-----------/ The WM_NOTIFY messages in the second case all come from the same HWND and control ID, so I cannot distinguish between the messages intended for SuperA (from Base) and messages intended for SuperB (from SuperA). Any ideas?

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• C++: Calling class functions within a switch

  - by user1446002

  i've been trying to study for my finals by practicing classes and inheritance, this is what I've come up with so far for inheritance and such however I'm unsure how to fix the error occuring below. #include<iostream> #include<iomanip> #include<cmath> #include<string.h> using namespace std; //BASE CLASS DEFINITION class hero { protected: string name; string mainAttr; int xp; double hp; double mana; double armour; int range; double attkDmg; bool attkType; public: void dumpData(); void getName(); void getMainAttr(); void getAttkData(); void setAttkData(string); void setBasics(string, string, double, double, double); void levelUp(); }; //CLASS FUNCTIONS void hero::dumpData() { cout << "Name: " << name << endl; cout << "Main Attribute: " << mainAttr << endl; cout << "XP: " << xp << endl; cout << "HP: " << hp << endl; cout << "Mana: " << mana << endl; cout << "Armour: " << armour << endl; cout << "Attack Range: " << range << endl; cout << "Attack Damage: " << attkDmg << endl; cout << "Attack Type: " << attkType << endl << endl; } void hero::getName() { cout << "Name: " << name << endl; } void hero::getMainAttr() { cout << "Main Attribute: " << mainAttr << endl; } void hero::getAttkData() { cout << "Attack Range: " << range << endl; cout << "Attack Damage: " << attkDmg << endl; cout << "Attack Type: " << attkType << endl; } void hero::setAttkData(string attr) { int choice = 0; if (attr == "Strength") { choice = 1; } if (attr == "Agility") { choice = 2; } if (attr == "Intelligence") { choice = 3; } switch (choice) { case 1: range = 128; attkDmg = 80.0; attkType = 0; break; case 2: range = 350; attkDmg = 60.0; attkType = 0; break; case 3: range = 600; attkDmg = 35.0; attkType = 1; break; default: break; } } void hero::setBasics(string heroName, string attribute, double health, double mp, double armourVal) { name = heroName; mainAttr = attribute; hp = health; mana = mp; armour = armourVal; } void hero::levelUp() { xp = 0; hp = hp + (hp * 0.1); mana = mana + (mana * 0.1); armour = armour + ((armour*0.1) + 1); attkDmg = attkDmg + (attkDmg * 0.05); } //INHERITED CLASS DEFINITION class neutHero : protected hero { protected: string drops; int xpGain; public: int giveXP(int); void dropItems(); }; //INHERITED CLASS FUNCTIONS int neutHero::giveXP(int exp) { xp += exp; } void neutHero::dropItems() { cout << name << " has dropped the following items: " << endl; cout << drops << endl; } /* END OF OO! */ //FUNCTION PROTOTYPES void dispMenu(); int main() { int exit=0, choice=0, mainAttrChoice=0, heroCreated=0; double health, mp, armourVal; string heroName, attribute; do { dispMenu(); cin >> choice; switch (choice) { case 1: system("cls"); cout << "Please enter your hero name: "; cin >> heroName; cout << "\nPlease enter your primary attribute\n"; cout << "1. Strength\n" << "2. Agility\n" << "3. Intelligence\n"; cin >> mainAttrChoice; switch (mainAttrChoice) { case 1: attribute = "Strength"; health = 750; mp = 150; armourVal = 2; break; case 2: attribute = "Agility"; health = 550; mp = 200; armourVal = 6; break; case 3: attribute = "Intelligence"; health = 450; mp = 450; armourVal = 1; break; default: cout << "Choice invalid, please try again."; exit = 1; break; hero player; player.setBasics(heroName, attribute, health, mp, armourVal); player.setAttkData(attribute); heroCreated=1; system("cls"); cout << "Your hero has been created!\n\n"; player.dumpData(); system("pause"); break; } case 2: system("cls"); if (heroCreated == 1) { cout << "Your hero has been detailed below.\n\n"; **player.dumpData(); //ERROR OCCURS HERE !** system("pause"); } else { cout << "You have not created a hero please exit this prompt " "and press 1 on the menu to create a hero."; } break; case 3: system("cls"); cout << "Still Under Development"; system("pause"); break; case 4: system("cls"); exit = 1; break; default: cout << "Your command has not been recognised, please try again.\n"; system("pause"); break; } } while (exit != 1); system("pause"); return 0; } void dispMenu() { system("cls"); cout << "1. Create New Hero\n" "2. View Current Hero\n" "3. Fight Stuff\n" "4. Exit\n\n" "Enter your choice: "; } However upon compilation I get the following errors: 220 `player' undeclared (first use this function) Unsure exactly how to fix it as I've only recently started using OO approach. The error has a comment next to it above and is in case 2 in the main. Cheers guys.

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• Trying to create XPath from this HTML snippet

  - by doneright

  I have played for a while writing XPath but am unable to come up with exactly what I want. I'm trying to write XPath for link(click1 and click2 in code snippet below) based on known text(myidentity in code snippet below). Can someone take a look into and suggest possible solution? HTML code snippet: <div class="abc"> <a onclick="mycontroller.goto('xx','yy'); return false;" href="#"> <img src="images/controls/inheritance.gif"/> </a> myidentity <span> <a onclick="mycontroller.goto('xx','yy'); return false;" href="#">click1</a> <a onclick="mycontroller.goto('xx','yy'); return false;" href="#">click2</a> </span> </div>

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• Retrieve only the superclass from a class hierarchy

  - by user1792724

  I have an scenario as the following: @Entity @Table(name = "ANIMAL") @Inheritance(strategy = InheritanceType.JOINED) public class Animal implements Serializable { @Id @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "S_ANIMAL") @SequenceGenerator(name = "S_ANIMAL", sequenceName = "S_ANIMAL", allocationSize = 1) public int getNumero() { return numero; } public void setNumero(int numero) { this.numero = numero; } . . . } and as the subclass: @Entity @Table(name = "DOG") public class Dog extends Animal { private static final long serialVersionUID = -7341592543130659641L; . . . } I have a JPA Select statement like this: SELECT a FROM Animal a; I'm using Hibernate 3.3.1 As I can see the framework retrieves instances of Animal and also of Dog using a left outer join. Is there a way to Select only the "part" Animal? I mean, the previous Select will get all the Animals, those that are only Animals but not Dogs and those that are Dogs. I want them all, but in the case of Dogs I want to only retrieve the "Animal part" of them. I found the @org.hibernate.annotations.Entity(polymorphism = PolymorphismType.EXPLICIT) but as I could see this only works if Animal isn't an @Entity. Thanks a lot.

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• how does one _model_ data from relational databases in clojure ?

  - by sandeep

  I have asked this question on twitter as well the #clojure IRC channel, yet got no responses. There have been several articles about Clojure-for-Ruby-programmers, Clojure-for-lisp-programmers.. but what is the missing part is Clojure for ActiveRecord programmers . There have been articles about interacting with MongoDB, Redis, etc. - but these are key value stores at the end of the day. However, coming from a Rails background, we are used to thinking about databases in terms of inheritance - has_many, polymorphic, belongs_to, etc. The few articles about Clojure/Compojure + MySQL (ffclassic) - delve right into sql. Of course, it might be that an ORM induces impedence mismatch, but the fact remains that after thinking like ActiveRecord, it is very difficult to think any other way. I believe that relational DBs, lend themselves very well to the object-oriented paradigm because of them being , essentially, Sets. Stuff like activerecord is very well suited for modelling this data. For e.g. a blog - simply put class Post < ActiveRecord::Base has_many :comments end class Comment < ActiveRecord::Base belongs_to :post end How does one model this in Clojure - which is so strictly anti-OO ? Perhaps the question would have been better if it referred to all functional programming languages, but I am more interested from a Clojure standpoint (and Clojure examples)

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• c++ Design pattern for CoW, inherited classes, and variable shared data?

  - by krunk

  I've designed a copy-on-write base class. The class holds the default set of data needed by all children in a shared data model/CoW model. The derived classes also have data that only pertains to them, but should be CoW between other instances of that derived class. I'm looking for a clean way to implement this. If I had a base class FooInterface with shared data FooDataPrivate and a derived object FooDerived. I could create a FooDerivedDataPrivate. The underlying data structure would not effect the exposed getters/setters API, so it's not about how a user interfaces with the objects. I'm just wondering if this is a typical MO for such cases or if there's a better/cleaner way? What peeks my interest, is I see the potential of inheritance between the the private data classes. E.g. FooDerivedDataPrivate : public FooDataPrivate, but I'm not seeing a way to take advantage of that polymorphism in my derived classes. class FooDataPrivate { public: Ref ref; // atomic reference counting object int a; int b; int c; }; class FooInterface { public: // constructors and such // .... // methods are implemented to be copy on write. void setA(int val); void setB(int val); void setC(int val); // copy constructors, destructors, etc. all CoW friendly private: FooDataPrivate *data; }; class FooDerived : public FooInterface { public: FooDerived() : FooInterface() {} private: // need more shared data for FooDerived // this is the ???, how is this best done cleanly? };

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• Namespace constraint with generic class decleration

  - by SomeGuy

  Good afternoon people, I would like to know if (and if so how) it is possible to define a namespace as a constraint parameter in a generic class declaration. What I have is this: namespace MyProject.Models.Entities <-- Contains my classes to be persisted in db namespace MyProject.Tests.BaseTest <-- Obvious i think Now the decleration of my 'BaseTest' class looks like so; public class BaseTest<T> This BaseTest does little more (at the time of writing) than remove all entities that were added to the database during testing. So typically I will have a test class declared as: public class MyEntityRepositoryTest : BaseTest<MyEntity> What i would LIKE to do is something similar to the following: public class BaseTest<T> where T : <is of the MyProject.Models.Entities namespace> Now i am aware that it would be entirely possible to simply declare a 'BaseEntity' class from which all entities created within the MyProject.Models.Entities namespace will inherit from; public class BaseTest<T> where T : MyBaseEntity but...I dont actually need to, or want to. Plus I am using an ORM and mapping entities with inheritance, although possible, adds a layer of complexity that is not required. So, is it possible to constrain a generic class parameter to a namespace and not a specific type ? Thank you for your time.

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• Find all CSS rules that apply to an element

  - by Carl Byström

  Many tools/APIs provide ways of selecting elements of specific classes or IDs. There's also possible to inspect the raw stylesheets loaded by the browser. However, for browsers to render an element, they'll compile all CSS rules (possibly from different stylesheet files) and apply it to the element. This is what you see with Firebug or the WebKit Inspector - the full CSS inheritance tree for an element. How can I reproduce this feature in pure JavaScript without requiring additional browser plugins? Perhaps an example can provide some clarification for what I'm looking for: <style type="text/css"> p { color :red; } #description { font-size: 20px; } </style> <p id="description">Lorem ipsum</p> Here the p#description element have two CSS rules applied: a red color and a font size of 20 px. I would like to find the source from where these computed CSS rules originate from (color comes the p rule and so on).

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• How to create a platform ontop of CSLA? <-- if in case it make sense

  - by Peejay

  Hi all! here is the senario, i'm developing an application using csla 3.8 / c#.net, the application will have different modules. its like an ERP, it will have accounting, daily time record, recruitment etc as modules. Now the requirement is to check for common entities per module and build a "platform" (<- the boss calls it that way) from it. for example, DTR will have an entity "employee", Recruitment will have "Applicant" so one common entity that you can derive from both that can be put in the platform is "Person". "Person" will contain typical info like name, address, contact info etc. I know it sounds like OOP 101. the thing is, i dont know how i am to go about it. how i wish it was just a simple inheritance but the requirement is like to create an API of some sort to be used by the modules using CSLA. in csla you create smart objects right, inheriting from the base classes of csla like businessListbase, readonlylistbase etc. right? what if for example i created a businessbase Applicant class, it will have properties like salary demand, availability date etc. now for the personal info i will need the "Person" from the "platform" and implement it to the applicant class. so in summary i have several questions: how to create such platform? if such platform is possible, how will it be implemented on each module's entities? (im already inheriting from base clases of csla) if incase 1 and 2 are possible, does it have advantages on development and maintenace of the app? the reason why i'm asking #3 is because the way i see it, even if i am able to create a platform for that, i will be needing to define properties of the platform entity on my module entities so to have validation and all. im sorry if i'm typing nonesense i'm really confused. hope someone could enlighten me. thank you all!

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• Use of 'super' keyword when accessing non-overridden superclass methods

  - by jonny

  I'm trying to get the hang of inheritance in Java and have learnt that when overriding methods (and hiding fields) in sub classes, they can still be accessed from the super class by using the 'super' keyword. What I want to know is, should the 'super' keyword be used for non-overridden methods? Is there any difference (for non-overridden methods / non-hidden fields)? I've put together an example below. public class Vehicle { public int tyreCost; public Vehicle(int tyreCost) { this.tyreCost = tyreCost; } public int getTyreCost() { return tyreCost; } } and public class Car extends Vehicle { public int wheelCount; public Vehicle(int tyreCost, int wheelCount) { super(tyreCost); this.wheelCount = wheelCount; } public int getTotalTyreReplacementCost() { return getTyreCost() * wheelCount; } } Specifically, given that getTyreCost() hasn't been overridden, should getTotalTyreReplacementCost() use getTyreCost(), or super.getTyreCost() ? I'm wondering whether super should be used in all instances where fields or methods of the superclass are accessed (to show in the code that you are accessing the superclass), or only in the overridden/hidden ones (so they stand out).

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• jQuery or CSS - How do you make a link in a table row appear underlined even when the cursor is in a

  - by adam

  I have a table of 3-4 columns, the central one being task names that are also links(yet another todo app..groan). Im trying to make it so that whenever the mouse hovers over any part of the table row - not just the link itself - the link will appear underlined. Its a small detail but its been annoying me like hell and i refuse to let it get the better of me now. At first i tried jQuery with a (forgive the obvious syntax errors but this is the jist) $('#row_in_question').hover( function(){ $(this).find(...the link..).toggleClass("highlighted") }, function(){ $(this).find(...the link..).toggleClass("highlighted") } ); with this as a styling for the a element in general .highlighted { text-decoration: underlined; } and it did indeed toggle the highlighted class on that link - however css inheritance got in the way and no visual changes made. Since i previously styled that link to have no underline when not hovered it wouldnt change the style. So how do i go about this? I dont want the whole row to become clickable, I just want the text to become underlined.

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• Is .NET 4.0 just a show?

  - by Will Marcouiller

  I went to a presentation about the .NET Framework and Visual Studio 2010, last night. The topis were: ASP.NET 4 - Some of the new features of ASP.NET 4 More control over ClientID's in WebForms; Output Caching; ... // Some other stuff I don't really remember being more in framework and WinForms world. Entity Framework 2.0 (.NET 4.0) T4 Templates; Domain driven development; Data driven development; Contexts (edmx files); Some of real-world limitations of EF4 (projects with over 70 to 75 tables); Better POCO support, despite there are still these hidden EntityObject and StructuralObject, but used differently in comparison to EF 1.0 so that it doesn't take off your inheritance; Allows to easily choose how to persist the hierarchy into the underlying database; Code only (start working with EF4 directly from your code!); Design by Contract (DbC). The most interesting feature is, and only, as far as I'm concerned, all related to parallelism made easier. Which really works! No additional assembly references to add. In conclusion, I'm far from impressed about .NET Framework 4.0, apart that it makes some things easier to do. But when you're used to make it a way, it doesn't really change much, in my opinion. Is it me who cannot foresee what .NET 4.0 has to offer? What would you guys base your decision on to migrate to .NET 4.0, in a practical way?

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• Is it poor design to create objects that only execute code during the constructor?

  - by Curtix

  In my design I am using objects that evaluate a data record. The constructor is called with the data record and type of evaluation as parameters and then the constructor calls all of the object's code necessary to evaluate the record. This includes using the type of evaluation to find additional parameter-like data in a text file. There are in the neighborhood of 250 unique evaluation types that use the same or similar code and unique parameters coming from the text file. Some of these evaluations use different code so I benefit a lot from this model because I can use inheritance and polymorphism. Once the object is created there isn't any need to execute additional code on the object (at least for now) and it is used more like a struct; its kept on a list and 3 properties are used later. I think this design is the easiest to understand, code, and read. A logical alternative I guess would be using functions that return score structs, but you can't inherit from methods so it would make it kind of sloppy imo. I am using vb.net and these classes will be used in an asp.net web app as well as in a distributed app. thanks for your input

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• JAXB code generation: how to remove a zero occurrence field?

  - by reef

  Hi all, I use JAXB 2.1 to generate Java classes from several XSD files, and I have a problem related to complex type restriction. On of the restrictions modifies the occurence configuration from minOccurs="0" maxOccurs="unbounded" to minOccurs="0" maxOccurs="0". Thus this field is not needed anymore in the restricted type. But actually JAXB generates the restricted class with a [0..1] cardinality instead of 0. By the way the generation is tuned with <xjc:treatRestrictionLikeNewType / so that a XSD restriction is not mapped to a Java class inheritance. Here is an example: Here is the way a field is defined in a complex type A: <element name="qualifier" type="CR" maxOccurs="unbounded" minOccurs="0"/ Here is the way the same field is restricted in another complex type B that restricts A: <element name="qualifier" type="CR" minOccurs="0" maxOccurs="0"/ In the A generated class I have: @XmlElement(name = "qualifier") protected List<CR qualifiers; And in the B generated class I have: protected CR qualifiers; With my poor understanding of JAXB the absence of the XmlElement annotation tells JAXB not to marshall/unmarshall this field. Am I wrong? If I am right is there a way to tell JAXB not to generate the qualifiers field at all? This would be in my opinion a much better generation as it respects the constraints. Any idea, thougths on the topic? Thanks!!

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• CreateProcess() fails with an access violation

  - by John Doe

  My aim is to execute an external executable in my program. First, I used system() function, but I don't want the console to be seen to the user. So, I searched a bit, and found CreateProcess() function. However, when I try to pass a parameter to it, I don't know why, it fails. I took this code from MSDN, and changed a bit: #include <windows.h> #include <stdio.h> #include <tchar.h> void _tmain( int argc, TCHAR *argv[] ) { STARTUPINFO si; PROCESS_INFORMATION pi; ZeroMemory( &si, sizeof(si) ); si.cb = sizeof(si); ZeroMemory( &pi, sizeof(pi) ); /* if( argc != 2 ) { printf("Usage: %s [cmdline]\n", argv[0]); return; } */ // Start the child process. if( !CreateProcess( NULL, // No module name (use command line) L"c:\\users\\e\\desktop\\mspaint.exe", // Command line NULL, // Process handle not inheritable NULL, // Thread handle not inheritable FALSE, // Set handle inheritance to FALSE 0, // No creation flags NULL, // Use parent's environment block NULL, // Use parent's starting directory &si, // Pointer to STARTUPINFO structure &pi ) // Pointer to PROCESS_INFORMATION structure ) { printf( "CreateProcess failed (%d).\n", GetLastError() ); return; } // Wait until child process exits. WaitForSingleObject( pi.hProcess, INFINITE ); // Close process and thread handles. CloseHandle( pi.hProcess ); CloseHandle( pi.hThread ); } However, this code crated access violation somehow. Can I execute mspaint without showing user the console? Thank you very much.

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• C++ design related question

  - by Kotti

  Hi! Here is the question's plot: suppose I have some abstract classes for objects, let's call it Object. It's definition would include 2D position and dimensions. Let it also have some virtual void Render(Backend& backend) const = 0 method used for rendering. Now I specialize my inheritance tree and add Rectangle and Ellipse class. Guess they won't have their own properties, but they will have their own virtual void Render method. Let's say I implemented these methods, so that Render for Rectangle actually draws some rectangle, and the same for ellipse. Now, I add some object called Plane, which is defined as class Plane : public Rectangle and has a private member of std::vector<Object*> plane_objects; Right after that I add a method to add some object to my plane. And here comes the question. If I design this method as void AddObject(Object& object) I would face trouble like I won't be able to call virtual functions, because I would have to do something like plane_objects.push_back(new Object(object)); and this should be push_back(new Rectangle(object)) for rectangles and new Circle(...) for circles. If I implement this method as void AddObject(Object* object), it looks good, but then somewhere else this means making call like plane.AddObject(new Rectangle(params)); and this is generally a mess because then it's not clear which part of my program should free the allocated memory. ["when destroying the plane? why? are we sure that calls to AddObject were only done as AddObject(new something).] I guess the problems caused by using the second approach could be solved using smart pointers, but I am sure there have to be something better. Any ideas?

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• interface variables are final and static by default and methods are public and abstract

  - by sap

  The question is why it's been decided to have variable as final and static and methods as public and abstract by default. Is there any particular reason for making them implicit,variable as final and static and methods as public and abstract. Why they are not allowing static method but allowing static variable? We have interface to have feature of multiple inheritance in Java and to avoid diamond problem. But how it solves diamond problem,since it does not allow static methods. In the following program, both interfaces have method with the same name..but while implementing only one we implement...is this how diamond problem is solved? interface testInt{ int m = 0; void testMethod(); } interface testInt1{ int m = 10; void testMethod(); } public class interfaceCheck implements testInt, testInt1{ public void testMethod(){ System . out . println ( "m is"+ testInt.m ); System . out . println ( "Hi World!" ); } }

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• JPA: persisting object, parent is ok but child not updated

  - by James.Elsey

  Hello, I have my domain object, Client, I've got a form on my JSP that is pre-populated with its data, I can take in amended values, and persist the object. Client has an abstract entity called MarketResearch, which is then extended by one of three more concrete sub-classes. I have a form to pre-populate some MarketResearch data, but when I make changes and try to persist the Client, it doesn't get saved, can someone give me some pointers on where I've gone wrong? My 3 domain classes are as follows (removed accessors etc) public class Client extends NamedEntity { @OneToOne @JoinColumn(name = "MARKET_RESEARCH_ID") private MarketResearch marketResearch; ... } @Inheritance(strategy = InheritanceType.JOINED) public abstract class MarketResearch extends AbstractEntity { ... } @Entity(name="MARKETRESEARCHLG") public class MarketResearchLocalGovernment extends MarketResearch { @Column(name = "CURRENT_HR_SYSTEM") private String currentHRSystem; ... } This is how I'm persisting public void persistClient(Client client) { if (client.getId() != null) { getJpaTemplate().merge(client); getJpaTemplate().flush(); } else { getJpaTemplate().persist(client); } } To summarize, if I change something on the parent object, it persists, but if I change something on the child object it doesn't. Have I missed something blatantly obvious? Thanks

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• Database choices

  - by flobadob

  I have a prickly design issue regarding the choice of database technologies to use for a group of new applications. The final suite of applications would have the following database requirements... Central databases (more than one database) using mysql (myst be mysql due to justhost.com). An application to be written which accesses the multiple mysql databases on the web host. This application will also write to local serverless database (sqlite/firebird/vistadb/whatever). Different flavors of this application will be created for windows (.NET), windows mobile, android if possible, iphone if possible. So, the design task is to minimise the quantity of code to achieve this. This is going to be tricky since the languages used are already c# / java (android) and objc (iphone). Not too worried about that, but can the work required to implement the various database access layers be minimised? The serverless database will hold similar data to the mysql server, so some kind of inheritance in the DAL would be useful. Looking at hibernate/nhibernate and there is linq to whatever. So many choices!

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• Why do I have to specify pure virtual functions in the declaration of a derived class in Visual C++?

  - by neuviemeporte

  Given the base class A and the derived class B: class A { public: virtual void f() = 0; }; class B : public A { public: void g(); }; void B::g() { cout << "Yay!"; } void B::f() { cout << "Argh!"; } I get errors saying that f() is not declared in B while trying do define void B::f(). Do I have to declare f() explicitly in B? I think that if the interface changes I shouldn't have to correct the declarations in every single class deriving from it. Is there no way for B to get all the virtual functions' declarations from A automatically? EDIT: I found an article that says the inheritance of pure virtual functions is dependent on the compiler: http://www.objectmentor.com/resources/articles/abcpvf.pdf I'm using VC++2008, wonder if there's an option for this.

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