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  • Jersey, JAXB and getting an objectextending an abstract class as a parameter

    - by krajol
    I want to get an object as a parameter of a POST request. I got an abstract superclass that is called Promotion and subclasses Product and Percent. Here's how I try to get a request: @POST @Consumes(MediaType.APPLICATION_XML) @Produces(MediaType.APPLICATION_XML) @Path("promotion/") public Promotion createPromotion(Promotion promotion) { Product p = (Product) promotion; System.out.println(p.getPriceAfter()); return promotion; } and here's how I use JAXB in classes' definitions: @XmlRootElement(name="promotion") @XmlSeeAlso({Product.class,Percent.class}) public abstract class Promotion { //body } @XmlRootElement(name="promotion") public class Product extends Promotion { //body } @XmlRootElement(name="promotion") public class Percent extends Promotion { //body } So the problem now is when I send a POST request with a body like this: <promotion> <priceBefore>34.5</priceBefore> <marked>false</marked> <distance>44</distance> </promotion> and I try to cast it to Product (as in this case, fields 'marked' and 'distance' are from Promotion class and 'priceBefore' is from Product class) I get an Exception: java.lang.ClassCastException: Percent cannot be cast to Product. It seems like Percent is chosen as a 'default' subclass. Why is that and how can I get an object that is a Product?

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  • Is private method in spring service implement class thread safe

    - by Roger Ray
    I got a service in an project using Spring framework. public class MyServiceImpl implements IMyService { public MyObject foo(SomeObject obj) { MyObject myobj = this.mapToMyObject(obj); myobj.setLastUpdatedDate(new Date()); return myobj; } private MyObject mapToMyObject(SomeObject obj){ MyObject myojb = new MyObject(); ConvertUtils.register(new MyNullConvertor(), String.class); ConvertUtils.register(new StringConvertorForDateType(), Date.class); BeanUtils.copyProperties(myojb , obj); ConvertUtils.deregister(Date.class); return myojb; } } Then I got a class to call foo() in multi-thread; There goes the problem. In some of the threads, I got error when calling BeanUtils.copyProperties(myojb , obj); saying Cannot invoke com.my.MyObject.setStartDate - java.lang.ClassCastException@2da93171 obviously, this is caused by ConvertUtils.deregister(Date.class) which is supposed to be called after BeanUtils.copyProperties(myojb , obj);. It looks like one of the threads deregistered the Date class out while another thread was just about to call BeanUtils.copyProperties(myojb , obj);. So My question is how do I make the private method mapToMyObject() thread safe? Or simply make the BeanUtils thread safe when it's used in a private method. And will the problem still be there if I keep the code this way but instead I call this foo() method in sevlet? If many sevlets call at the same time, would this be a multi-thread case as well?

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  • C++ Virtual Methods for Class-Specific Attributes or External Structure

    - by acanaday
    I have a set of classes which are all derived from a common base class. I want to use these classes polymorphically. The interface defines a set of getter methods whose return values are constant across a given derived class, but vary from one derived class to another. e.g.: enum AVal { A_VAL_ONE, A_VAL_TWO, A_VAL_THREE }; enum BVal { B_VAL_ONE, B_VAL_TWO, B_VAL_THREE }; class Base { //... virtual AVal getAVal() const = 0; virtual BVal getBVal() const = 0; //... }; class One : public Base { //... AVal getAVal() const { return A_VAL_ONE }; BVal getBVal() const { return B_VAL_ONE }; //... }; class Two : public Base { //... AVal getAVal() const { return A_VAL_TWO }; BVal getBVal() const { return B_VAL_TWO }; //... }; etc. Is this a common way of doing things? If performance is an important consideration, would I be better off pulling the attributes out into an external structure, e.g.: struct Vals { AVal a_val; VBal b_val; }; storing a Vals* in each instance, and rewriting Base as follows? class Base { //... public: AVal getAVal() const { return _vals->a_val; }; BVal getBVal() const { return _vals->b_val; }; //... private: Vals* _vals; }; Is the extra dereference essentially the same as the vtable lookup? What is the established idiom for this type of situation? Are both of these solutions dumb? Any insights are greatly appreciated

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  • NHibernate class referencing discriminator based subclass

    - by Rich
    I have a generic class Lookup which contains code/value properties. The table PK is category/code. There are subclasses for each category of lookup, and I've set the discriminator column in the base class and its value in the subclass. See example below (only key pieces shown): public class Lookup { public string Category; public string Code; public string Description; } public class LookupClassMap { CompositeId() .KeyProperty(x = x.Category, "CATEGORY_ID") .KeyProperty(x = x.Code, "CODE_ID"); DiscriminateSubclassesBasedOnColumn("CATEGORY_ID"); } public class MaritalStatus: Lookup {} public class MartialStatusClassMap: SubclassMap { DiscriminatorValue(13); } This all works. Here's the problem. When a class has a property of type MaritalStatus, I create a reference based on the contained code ID column ("MARITAL_STATUS_CODE_ID"). NHibernate doesn't like it because I didn't map both primary key columns (Category ID & Code ID). But with the Reference being of type MaritalStatus, NHibernate should already know what the value of the category ID is going to be, because of the discriminator value. What am I missing?

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  • Cannot redeclare class on a copy of a site

    - by Polity
    I've developed a small SMS utility for a customer in PHP. The details are of non-importance. This project is hosted in: http://project.example.com/customer1 Now a second customer requests almost the same functionality, one cheap way of providing this is to copy the project from the first customer and modify it slightly. So i made a direct copy of the project for customer1 to another folder for customer 2. This project is hosted in: http://project.example.com/customer2 Now when i try and run the project for customer2 (calling a single page), i get the error message: Fatal error: Cannot redeclare class SmsService in /var/www/html/project/customer1/application/service.class.php on line 3 Here, service.class.php is a simple interface with 3 methods: interface SmsService { public function SendSms($mobile, $customerId, $customerName, $message); public function QueryIncomingResponse(); public function CleanExpiredConfirmations($maxConfirmationDays); } printing the backtrace in service.class.php reveals something interresting: #0 require_once() called at [/var/www/html/project/customer2/endpoint/queryIncomingResponse.php:2] Fatal error: Cannot redeclare class SmsService in /var/www/html/project/customer1/application/service.class.php on line 3 Line 2 in queryIncomingResponses is the very first require line there is. Line 3 in service.class.php is the first statement there is in the file (Line 2 is an empty line and line 1 is the php file opening tag). Naturally, I only work with relative requires (double checked this) so there is no way one include/require from customer2 actually refers to a file for customer1. It seems to me that in some way SmsService and other classes gets cached by PHP. (I have little control over the server environment). One solution to this would be namespaces. Unfortunatly, we work with PHP 5.1.7 where namespaces are not a part of the language feature just yet. Another way would be to mimic namespaces by prefixing all classes but this approach just feels dirty. Does anyone have more information on this problem and possibly solutions? Many thanks in advance!

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  • Managed WMI Event class is not an event class???

    - by galets
    I am using directions from here: http://msdn.microsoft.com/en-us/library/ms257351(VS.80).aspx to create a managed event class. Here's the code that I wrote: [ManagementEntity] [InstrumentationClass(InstrumentationType.Event)] public class MyEvent { [ManagementKey] public string ID { get; set; } [ManagementEnumerator] static public IEnumerable<MyEvent> EnumerateInstances() { var e = new MyEvent() { ID = "9A3C1B7E-8F3E-4C54-8030-B0169DE922C6" }; return new MyEvent[] { e }; } } class Program { static void Main(string[] args) { var thisAssembly = typeof(Program).Assembly; var wmi_installer = new AssemblyInstaller(thisAssembly, null); wmi_installer.Install(null); wmi_installer.Commit(null); InstrumentationManager.RegisterAssembly(thisAssembly); Console.Write("Press Enter..."); Console.ReadLine(); var e = new MyEvent() { ID = "A6144A9E-0667-415B-9903-220652AB7334" }; Instrumentation.Fire(e); Console.Write("Press Enter..."); Console.ReadLine(); wmi_installer.Uninstall(null); } } I can run a program, and it properly installs. Using wbemtest.exe I can browse to the event, and "show mof": [dynamic: ToInstance, provider("WmiTest, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null")] class MyEvent { [read, key] string ID; }; Notice, the class does not inherit from __ExtrinsicEvent, which is weird... I can also run select * from MyEvent, and get the result. Instrumentation.Fire() also returns no error. However, when I'm trying to subscribe to event using "Notification Query" option, I'm getting 0x80041059 Number: 0x80041059 Facility: WMI Description: Class is not an event class. What am I doing wrong, and is there a correct way to create managed WMI event?

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  • how to do validations when composing object of a class in other class ?

    - by haansi
    Hi, I have an IPAddress class which has one property named ip and in its setter I am validating data coming and if data is invalid it throws an error. (Its code is as the following): private string ip; public string IP { get { return ip; } set { string PartsOfIP = value.Split('.'); if (PartsOfIP.Length == 4) { foreach (string part in PartsOfIP) { int a = 0; bool result = int.TryParse(part, out a); if (result != true) { throw new Exception("Invalid IP"); } else { ip = value; } } } else { throw new Exception("Invalid IP"); } } In User Class I want to compose an object of IPAddress class. I am doing validations for properties of User in User class and validations of Ip in IPAddress class. My question is how I will compose IPAddress object in UserClass and what will be syntax for this ? If I again mention get and set here with IPAddress object in User class will my earlier mentioned (in IPAddress class) getter and setter work ? plz advice me in details thanks

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  • C# Casting system.__comobject to class type

    - by ijrufus
    I have an Excel Add-In that I'm currently trying to set up a unit test framework for. For the unit tests I've followed this guide: http://blogs.msdn.com/b/varsha/archive/2010/08/17/writing-automated-test-cases-for-vsto-application.aspx It seems to work fine, until I want to return a class object from my interface. Specifying the class object as the return type throws a "return argument has an invalid type" exception when calling the method. Changing the return type from the class to an object allows me to call the method and get the object, but now I'm unable to cast it as the class and use it as intended, getting this exception message when I try: > Unable to cast COM object of type 'System.__ComObject' to class type > 'anaplan.Utility.XYCoordinates'. Instances of types that represent COM > components cannot be cast to types that do not represent COM > components; however they can be cast to interfaces as long as the > underlying COM component supports QueryInterface calls for the IID of > the interface. I've retrieved the Type name using VisualBasic.Information.TypeName and it's showing it as the class I expect. Is there any way to get the comobject cast back to the class? Or another way to access the properties it has? Or am I just being a bit stupid here?

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  • Java program using a class from a JAR file

    - by Myn
    Hi guys, I'll try to phrase this as best I can. I have a program which has an API-like functionality - it uses reflection to dynamically call methods from within a class. In this instance: Server.java public static void main(String[] args) { Class<?> clazz = Class.forName("DiHandler"); StHandler out = (StHandler) clazz; out.read(); DiHandler.java // implements StHandler import edu.ds.*; public void read() { Ds aType = new Ds(); aType = "134"; } So DiHandler has a method read() which can contain anything, it doesn't matter to Server.java after compile time. My problem is: DiHandler.java uses the class Ds from a JAR file. When I'm working on DiHandler.java in Eclipse (in a separate project from the project Server.java is in) I can add this JAR without a problem. But when I move DiHandler.class, after it's compiled, to be used by Server.class, how can it still use the JAR file? I hope this makes some sense, I suppose another way to phrase it would be how can I allow DiHandler to call on a class from the JAR without editing the classpath? Thanks very much in advance and sorry for any confusion or poor phrasing, I can only offer thanks and the customary offer of a pint for any assistance. M

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  • Array Indexing Properties of A Class

    - by Chris
    I have a class that has several properties: class Person { string Name; int Age; DateTime BirthDate; } Then I have a sort of wrapper class with a List<Person>. Within this wrapper class I want to be able to do something like Wrapper["Name"] that returns a new List<string> using .Select(x=>x.Name). How do I create a wrapper class around an IEnumerable that supports mapping a string to the Property name? Something like the pseudo code below, but obviously it doesn't work. I'm 99.9% sure the solution will have to use Reflection and thats fine. class Wrapper { List<Person> PersonList; List<dynamic> this[string Column] { return PersonList.Select(x => x.[Column]).ToList(); } } This may not seem like a good design, but its a fix to eventually enable the correct design from .NET 2.0 days. As I have it right now, the data is stored in Columns, so there is actually a List of Lists within my class right now. Using the above example there would be three ILists (with a string Title) Name, Age, and Birthdate. Everything is currently predicated on addressing the columns by their "string" name. I'm trying to convert the data structure to row based with an IEnumberable interface to allow Linq eventually while still maintaining the functionality of my current code. Is converting the code to a Row based IEnumberable a good idea?

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  • Find class in table row

    - by meep
    Hello. Take a look at this table: <table cellpadding="0" cellspacing="0" class="order_form"> <tr> <th>Amount</th> <th>Desc</th> <th>Price</th> <th>Total</th> </tr> <tr> <td><input type="text" class="order_count" /></td> <td> <span class="order_desc">Middagstallerken</span> </td> <td> <span class="order_price">1,15</span> </td> <td> <span class="order_each_total"></span> </td> </tr> [...] </table> Upon entering amount I need to select the class "order_price" and multiply it with the value of the input "order_count" and place it in "order_each_count". I have millions of these rows so I need to find the next class in the row. I have tried using some function like this but without result: <script type="text/javascript"> $(document).ready(function(){ $('.order_count').keyup(function() { var each_price = $(this).prevUntil("tr").find("span.order_price").text(); }); }); </script> I hope someone have a good solution :-)

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  • Best way to create a collection of a class

    - by smartins
    I'm trying to create some classes that allow me to retrieve and manipulate a set of backups my application will create and manage. I've come up with the following code (not tested yet), but I'm not sure if it's the best way of accomplishing this or if there's any easier/better way. I'm using Delphi 2010. I have a class that holds the backup details (TBackupItem), then I need to have a class that will hold a collection of TBackupItem and finally I'll have a class that manages the reading and writing of backups and also exposes a property that accesses the collection of TBackupItem. type TBackupItem = class private FBackupProgram: string; FBackupProgramVersion: string; // There are more variables and properties but for the sake of simplicity I've listed only two public property BackupProgram: string read FBackupProgram write FBackupProgram; property BackupProgramVersion: string read FBackupProgramVersion write FBackupProgramVersion; end; TBackupsList = class(???) private // This class will hold a list of TBackupItem. What should I use to accomplish this? end; TBackupsManager = class(TObject) private FBackups: TBackupsList; public property Backups: TBackupsList read FBackups write FBackups; end; Do you guys have any comments and/or examples on the best way of accomplishing this? Thanks!

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  • Extending the CI_DB_active_record class in codeigniter 2.0

    - by ctrane
    I am writing my first program with Codeigniter, and have run into a problem. I will start with a focused description of the problem and can broaden it if I need to: I need to write a multi-dimensional array to the DB and want to use the insert_batch function from the CI_DB_active_record class to do so. The problem is that I need to write empty values as NULL for some fields while other fields need to be empty strings. The current function wraps all values with single quotes, and I cannot find a way to write null values to the database for specified fields. I would also like to increase the number of records per batch. I see how to extend models, libraries, etc., but is there a way to extend the CI_DB_active_record class without modifying core classes? The minimal amount of core class modification to make this work that I have found is modifying the following lines in the DB.php file (changing the require_once file to the new file that extends the CI_DB_active_record class and changing the CI_DB_active_record class name to the new class name): require_once(BASEPATH.'database/DB_active_rec'.EXT); if ( ! class_exists('CI_DB')) { eval('class CI_DB extends CI_DB_active_record { }'); } Can I do better?

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  • IOC Container Handling State Params in Non-Default Constructor

    - by Mystagogue
    For the purpose of this discussion, there are two kinds of parameters an object constructor might take: state dependency or service dependency. Supplying a service dependency with an IOC container is easy: DI takes over. But in contrast, state dependencies are usually only known to the client. That is, the object requestor. It turns out that having a client supply the state params through an IOC Container is quite painful. I will show several different ways to do this, all of which have big problems, and ask the community if there is another option I'm missing. Let's begin: Before I added an IOC container to my project code, I started with a class like this: class Foobar { //parameters are state dependencies, not service dependencies public Foobar(string alpha, int omega){...}; //...other stuff } I decide to add a Logger service depdendency to the Foobar class, which perhaps I'll provide through DI: class Foobar { public Foobar(string alpha, int omega, ILogger log){...}; //...other stuff } But then I'm also told I need to make class Foobar itself "swappable." That is, I'm required to service-locate a Foobar instance. I add a new interface into the mix: class Foobar : IFoobar { public Foobar(string alpha, int omega, ILogger log){...}; //...other stuff } When I make the service locator call, it will DI the ILogger service dependency for me. Unfortunately the same is not true of the state dependencies Alpha and Omega. Some containers offer a syntax to address this: //Unity 2.0 pseudo-ish code: myContainer.Resolve<IFoobar>( new parameterOverride[] { {"alpha", "one"}, {"omega",2} } ); I like the feature, but I don't like that it is untyped and not evident to the developer what parameters must be passed (via intellisense, etc). So I look at another solution: //This is a "boiler plate" heavy approach! class Foobar : IFoobar { public Foobar (string alpha, int omega){...}; //...stuff } class FoobarFactory : IFoobarFactory { public IFoobar IFoobarFactory.Create(string alpha, int omega){ return new Foobar(alpha, omega); } } //fetch it... myContainer.Resolve<IFoobarFactory>().Create("one", 2); The above solves the type-safety and intellisense problem, but it (1) forced class Foobar to fetch an ILogger through a service locator rather than DI and (2) it requires me to make a bunch of boiler-plate (XXXFactory, IXXXFactory) for all varieties of Foobar implementations I might use. Should I decide to go with a pure service locator approach, it may not be a problem. But I still can't stand all the boiler-plate needed to make this work. So then I try this: //code named "concrete creator" class Foobar : IFoobar { public Foobar(string alpha, int omega, ILogger log){...}; static IFoobar Create(string alpha, int omega){ //unity 2.0 pseudo-ish code. Assume a common //service locator, or singleton holds the container... return Container.Resolve<IFoobar>( new parameterOverride[] {{"alpha", alpha},{"omega", omega} } ); } //Get my instance: Foobar.Create("alpha",2); I actually don't mind that I'm using the concrete "Foobar" class to create an IFoobar. It represents a base concept that I don't expect to change in my code. I also don't mind the lack of type-safety in the static "Create", because it is now encapsulated. My intellisense is working too! Any concrete instance made this way will ignore the supplied state params if they don't apply (a Unity 2.0 behavior). Perhaps a different concrete implementation "FooFoobar" might have a formal arg name mismatch, but I'm still pretty happy with it. But the big problem with this approach is that it only works effectively with Unity 2.0 (a mismatched parameter in Structure Map will throw an exception). So it is good only if I stay with Unity. The problem is, I'm beginning to like Structure Map a lot more. So now I go onto yet another option: class Foobar : IFoobar, IFoobarInit { public Foobar(ILogger log){...}; public IFoobar IFoobarInit.Initialize(string alpha, int omega){ this.alpha = alpha; this.omega = omega; return this; } } //now create it... IFoobar foo = myContainer.resolve<IFoobarInit>().Initialize("one", 2) Now with this I've got a somewhat nice compromise with the other approaches: (1) My arguments are type-safe / intellisense aware (2) I have a choice of fetching the ILogger via DI (shown above) or service locator, (3) there is no need to make one or more seperate concrete FoobarFactory classes (contrast with the verbose "boiler-plate" example code earlier), and (4) it reasonably upholds the principle "make interfaces easy to use correctly, and hard to use incorrectly." At least it arguably is no worse than the alternatives previously discussed. One acceptance barrier yet remains: I also want to apply "design by contract." Every sample I presented was intentionally favoring constructor injection (for state dependencies) because I want to preserve "invariant" support as most commonly practiced. Namely, the invariant is established when the constructor completes. In the sample above, the invarient is not established when object construction completes. As long as I'm doing home-grown "design by contract" I could just tell developers not to test the invariant until the Initialize(...) method is called. But more to the point, when .net 4.0 comes out I want to use its "code contract" support for design by contract. From what I read, it will not be compatible with this last approach. Curses! Of course it also occurs to me that my entire philosophy is off. Perhaps I'd be told that conjuring a Foobar : IFoobar via a service locator implies that it is a service - and services only have other service dependencies, they don't have state dependencies (such as the Alpha and Omega of these examples). I'm open to listening to such philosophical matters as well, but I'd also like to know what semi-authorative reference to read that would steer me down that thought path. So now I turn it to the community. What approach should I consider that I havn't yet? Must I really believe I've exhausted my options?

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  • How to improve the builder pattern?

    - by tangens
    Motivation Recently I searched for a way to initialize a complex object without passing a lot of parameter to the constructor. I tried it with the builder pattern, but I don't like the fact, that I'm not able to check at compile time if I really set all needed values. Traditional builder pattern When I use the builder pattern to create my Complex object, the creation is more "typesafe", because it's easier to see what an argument is used for: new ComplexBuilder() .setFirst( "first" ) .setSecond( "second" ) .setThird( "third" ) ... .build(); But now I have the problem, that I can easily miss an important parameter. I can check for it inside the build() method, but that is only at runtime. At compile time there is nothing that warns me, if I missed something. Enhanced builder pattern Now my idea was to create a builder, that "reminds" me if I missed a needed parameter. My first try looks like this: public class Complex { private String m_first; private String m_second; private String m_third; private Complex() {} public static class ComplexBuilder { private Complex m_complex; public ComplexBuilder() { m_complex = new Complex(); } public Builder2 setFirst( String first ) { m_complex.m_first = first; return new Builder2(); } public class Builder2 { private Builder2() {} Builder3 setSecond( String second ) { m_complex.m_second = second; return new Builder3(); } } public class Builder3 { private Builder3() {} Builder4 setThird( String third ) { m_complex.m_third = third; return new Builder4(); } } public class Builder4 { private Builder4() {} Complex build() { return m_complex; } } } } As you can see, each setter of the builder class returns a different internal builder class. Each internal builder class provides exactly one setter method and the last one provides only a build() method. Now the construction of an object again looks like this: new ComplexBuilder() .setFirst( "first" ) .setSecond( "second" ) .setThird( "third" ) .build(); ...but there is no way to forget a needed parameter. The compiler wouldn't accept it. Optional parameters If I had optional parameters, I would use the last internal builder class Builder4 to set them like a "traditional" builder does, returning itself. Questions Is this a well known pattern? Does it have a special name? Do you see any pitfalls? Do you have any ideas to improve the implementation - in the sense of fewer lines of code?

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  • DRY programming dilemma

    - by fayer
    the situation is like this: im creating a Logger class that can write to a file but the write_to_file() function is in a helper class as a static function. i could call that function but then the Log class would be dependent to the helper class. isn't dependency bad? but if i can let it use a helper function then what is the point of having helper functions? what should one prioritize here: using helper functions and have to include this helper class everywhere (but the other 99 methods wont be useful) or just copy and paste into the Log class (but then if i have done this 100 times and then make a change i have to change in 100 places). share your thoughts and experience!

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  • Make is more OOPey - good structure?

    - by Tom
    Hi, I just want advice on whether I could improve structure around a particular class which handles all disk access functions The structure of my program is that I have a class called Disk which gets data from flatfiles and databases on a, you guessed it, hard disk drive. I have functions like LoadTextFileToStringList, WriteStringToTextFile, DeleteLineInTextFile etc which are kind of "generic methods" In the same class I also have some more specific methods such as GetXFromDisk where X might be a particular field in a database table/query. Should I separate out the generic methods from the specialised. Should I make another class which inherits the generic methods. At the moment my class is static as there is no need to have an internal state of the class. I'm not really OOPing am I? Thanks Thomas

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  • Repeating fields in similar database tables

    - by user1738833
    I have been tasked with working on a database that I have never seen before and I'm looking at the DB structure. Some of the central and most heavily queried and joined tables look like virtual duplicates of each other. Here's a massively simplified representation of the situation, with business-sensitive information changed, listing hypothetical table names and fields: TopLevelGroup: PK_TLGroupId, DisplaysXOnBill, DisplaysYOnBill, IsInvoicedForJ, IsInvoicedForK SubGroup: PK_SubGroupId, FK_ParentTopLevelGroupId, DisplaysXOnBill, DisplaysYOnBill, IsInvoicedForJ, IsInvoicedForK SubSubGroup: PK_SubSUbGroupId, FK_ParentSubGroupId, DisplaysXOnBill, DisplaysYOnBill, IsInvoicedForJ, IsInvoicedForK I haven't listed the types of the fields as I don't think it's particularly important to the situation. In addition, it's worth saying that rather than four repeated fields as in the example above, I'm looking at 86 repeated fields. For the most part, those fields genuinely do represent "facts" about the primary table entity, so it's not automatically wrong for that reason. In addition, the "groups" represented here have a property inheritance relationship. If DisplaysXOnBill is NULL in the SubSubGroup, it takes the value of DisplaysXOnBillfrom it's parent, the SubGroup, and so-on up to the TopLevelGroup. Further, the requirements will never require that the model extends beyond three levels, so there is no need for flexibility in that area. Is there a design smell from several tables which describe very similar entities having almost identical fields? If so, what might be a better design of the example above? I'm using the phrase "design smell" to indicate a possible problem. Of course, in any given situation, a particular design might well be the best solution. I'm looking for a more general answer - wondering what might be wrong with this design and what might be the better design were that the case. Possibly related, but not primary questions: Is this database schema in a reasonably normal form (e.g. to 3NF), insofar as can be told from the information I've provided. I can't see a problem with the requirements of 2NF and 3NF, except in their inheriting the requirements of 1NF. Is 1NF satisfied though? Are repeating groups allowed in different tables? Is there a best-practice method for implementing the inheritance relationship in a database as I require? The method above feels clunky to me because any query on the SubSubGroup necessarily needs to join onto the SubGroup and the TopLevelGroup tables to collect inherited facts, which can make even trivial joins requiring facts from the SubSubGroup table rather long-winded. There are, of course, political considerations to making a relatively large change like this. For the purpose of this question, I'm happy to ignore that fact in the interests of keeping the answers ring-fenced to the technical problem.

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  • CSS: How the backgrounds can extend the border and overlap?

    - by AlexStack
    I'm designing a navigation bar as shown in image below (a) with the following code: <ul> <li class="unselected">Step 1</li> <li class="selected">Step 2</li> <li class="unselected">Step 3</li> <li class="unselected">Step 4</li> <li class="unselected">Step 5</li> </ul> I want to have one background image for unselected steps (d) and one for the selected step (c). For simplicity let's assume Step 1 and Step 5 use the same background as well. I want to adjust the button background in HTML only with a class name. The question is how can I achieve the result with CSS? I just want to know how background of two neighbor elements can overlap each other?

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  • Struct like objects in Java

    - by cdv
    Is it completely against the Java way to create struct like objects? class SomeData1 { public int x; public int y; } I can see a class with accessors and mutators being more Java like. class SomeData2 { int getX(); void setX(int x); int getY(); void setY(int y); private int x; private int y; } The class from the first example is notationally convenient. // a function in a class public int f(SomeData1 d) { return (3 * d.x) / d.y; } This is not as convenient. // a function in a class public int f(SomeData2 d) { return (3 * d.getX()) / d.getY(); }

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  • Group policy results failing with "Invalid class" error

    - by bshacklett
    When trying to run the Group Policy Results Wizard against a specific workstation, I'm getting the following error: The wizard was unable to generate the computer or user's data due to insufficient permissions. Details: Invalid class I'm guessing that the class being referred to is a WMI class, but I haven't gotten much farther. I've run sfc /scannow on the machine with no luck. I've also followed all of the recommendations in this article: http://windowsxp.mvps.org/repairwmi.htm. I cannot find anything useful in the event logs and I can't think of anywhere else I could look to find out what's really happening here. Any help would be appreciated.

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  • Why does an error appear every time I try to open the Ubuntu Software Center? [duplicate]

    - by askubuntu7639
    This question already has an answer here: How do I remove a broken software source? 3 answers There is a glitch on the Ubuntu Software Center and whenever I open it an error appears and it keeps loading and never opens. Why does this happen? I have installed Ubuntu 13.04 on a disk and partitioned it. Please help me and ask for excess information if you need it. If you know of any duplicates please show me them!! This is the output of a question someone asked me. SystemError: E:Type '<!DOCTYPE' is not known on line 1 in source list /etc/apt/sources.list.d/medibuntu.list This next output is the output of cat /etc/apt/sources.list.d/medibuntu.list </div> <div style="float:left;"> <div class="textwidget"><script type="text/javascript"><!-- google_ad_client = "ca-pub-2917661377128354"; /* 160X600 Sidebar UX */ google_ad_slot = "9908287444"; google_ad_width = 160; google_ad_height = 600; //-- Recent Comments <article> <div style="float:left; display:block; margin:0 10px 10px 0; border:1px solid #CCCCCC; padding:3px; width:35px; height:35px;"><img alt='' src='http://0.gravatar.com/avatar/ae5f4503d5f167f1cf62d3e36e8242b6?s=35&amp;d=&amp;r=G' class='avatar avatar-35 photo' height='35' width='35' /></div> <div style="float:left;"> <h4 class="author">Richard Syme</h4> <p class="meta"> <time datetime="2013-09-24" pubdate>September 24, 2013</time> | <a class="permalink" href="http://www.unixmen.com/how-to-customize-you-vlc-hot-keys/#comment-13732">#</a> </p> </div> <div class="content" style="float:left;"><p>I dont have a clear button under the hotkeys. All i want to do is get rid of all hotkeys.</p> </article> <article> <div style="float:left; display:block; margin:0 10px 10px 0; border:1px solid #CCCCCC; padding:3px; width:35px; height:35px;"><img alt='' src='http://1.gravatar.com/avatar/ffabde94437e996a506e31e981bcf8fc?s=35&amp;d=&amp;r=G' class='avatar avatar-35 photo' height='35' width='35' /></div> <div style="float:left;"> <h4 class="author">Abin Thomas Mathew</h4> <p class="meta"> <time datetime="2013-09-24" pubdate>September 24, 2013</time> | <a class="permalink" href="http://www.unixmen.com/install-lamp-server-in-centos-6-4-rhel-6-4/#comment-13727">#</a> </p> </div> <div class="content" style="float:left;"><p>Simple and easy to follow tutorial to install and start of phpMyAdmin. Thank you</p> </article> <article> <div style="float:left; display:block; margin:0 10px 10px 0; border:1px solid #CCCCCC; padding:3px; width:35px; height:35px;"><img alt='' src='http://0.gravatar.com/avatar/499ccc1154e9b8569b87413434220b91?s=35&amp;d=&amp;r=G' class='avatar avatar-35 photo' height='35' width='35' /></div> <div style="float:left;"> <h4 class="author">SK</h4> <p class="meta"> <time datetime="2013-09-24" pubdate>September 24, 2013</time> | <a class="permalink" href="http://www.unixmen.com/munich-giving-ubuntu-linux-cds-citizens/#comment-13725">#</a> </p> </div> <div class="content" style="float:left;"><p>I have Bosslinux and i used it for a while. Now i swiched to Ubuntu 13.04.</p> </article> <article> <div style="float:left; display:block; margin:0 10px 10px 0; border:1px solid #CCCCCC; padding:3px; width:35px; height:35px;"><img alt='' src='http://1.gravatar.com/avatar/3dc2f7140bdd857dcdfe815a6e29aa6b?s=35&amp;d=&amp;r=G' class='avatar avatar-35 photo' height='35' width='35' /></div> <div style="float:left;"> <h4 class="author">Anon</h4> <p class="meta"> <time datetime="2013-09-24" pubdate>September 24, 2013</time> | <a class="permalink" href="http://www.unixmen.com/linus-torvalds-talks-backdoor-linuxcon/#comment-13724">#</a> </p> </div> <div class="content" style="float:left;"><p>Do you know how much extra bloat is in Ubuntu these days? How the hell does anyone really know?</p> </article> <article> <div style="float:left; display:block; margin:0 10px 10px 0; border:1px solid #CCCCCC; padding:3px; width:35px; height:35px;"><img alt='' src='http://1.gravatar.com/avatar/9dd28d1cf5efe754fa58b53c1e6de401?s=35&amp;d=&amp;r=G' class='avatar avatar-35 photo' height='35' width='35' /></div> <div style="float:left;"> <h4 class="author"><a href="http://ambitiousgeeks.blogspot.com/" onclick="javascript:_gaq.push(['_trackEvent','outbound-commentauthor','http://ambitiousgeeks.blogspot.com']);" rel='external nofollow' class='url'>Ambition</a></h4> <p class="meta"> <time datetime="2013-09-24" pubdate>September 24, 2013</time> | <a class="permalink" href="http://www.unixmen.com/linus-torvalds-talks-backdoor-linuxcon/#comment-13723">#</a> </p> </div> <div class="content" style="float:left;"><p>True :)</p> </article> </div> <div style="float:left;"> &nbsp;<script type="text/javascript"> window.___gcfg = {lang: 'en-US'}; (function() {var po = document.createElement("script"); po.type = "text/javascript"; po.async = true;po.src = "https://apis.google.com/js/plusone.js"; var s = document.getElementsByTagName("script")[0]; s.parentNode.insertBefore(po, s); })(); <div class="execphpwidget"></div> </div> <div class="module2"> <div class="recentPost"> <h3 class="module-title2">Favorite Links</h3> <ul class='xoxo blogroll'> http://www.iticy.com']);"Cheap Hosting http://www.tuxmachines.org']);"TuxMachines.org http://www.ubuntugeek.com']);"UbuntuGeek.com http://www.stelinuxhost.com']);"Webdesign & SEO </ul> <img src="http://180016988.r.cdn77.net/wp-content/themes/unimax/images/bigLine.jpg" alt="" /> </div> </div> <div align="center" style="min-height:610px;"> <div class="execphpwidget"></div> <div class="textwidget"><a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en_US" onclick="javascript:_gaq.push(['_trackEvent','outbound-widget','http://creativecommons.org']);"><img alt="Creative Commons License" style="border-width:0" src="http://i.creativecommons.org/l/by-nc-nd/3.0/88x31.png" /></a><br />This work by <a xmlns:cc="http://creativecommons.org/ns#" href="unixmen.com" property="cc:attributionName" rel="cc:attributionURL">unixmen.com</a> is licensed under a <a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en_US" >Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License</a>.</div> </div> </div> <!-- #primary .widget-area --> </div> Unixmen Archive Select Month September 2013 August 2013 July 2013 June 2013 May 2013 April 2013 March 2013 February 2013 January 2013 December 2012 November 2012 October 2012 September 2012 August 2012 July 2012 June 2012 May 2012 April 2012 March 2012 February 2012 January 2012 December 2011 November 2011 October 2011 September 2011 August 2011 July 2011 June 2011 May 2011 April 2011 March 2011 February 2011 January 2011 December 2010 November 2010 October 2010 September 2010 August 2010 July 2010 June 2010 May 2010 April 2010 March 2010 February 2010 January 2010 December 2009 November 2009 October 2009 September 2009 August 2009 July 2009 June 2009 May 2009 April 2009 March 2009 February 2009 January 2009 December 2008 Tags Cloudandroid apache browser Centos chrome command line Debian eyecandy Fedora firefox games gaming gnome google karmic koala kde libreoffice Linux linux distribution LinuxMint lucid lynx maverick meerkat mysql news oneiric ocelot openoffice opensource opensuse oracle ppa Precise Pangolin release RHEL security server software themes tools ubuntu unix upgrade virtualbox vlc windows wine Unixmen Twitts Firefox 16, a treat for developers http://t.co/cnd27CzT Ubuntu 12.10 ‘Quantal Quetzal’: Beta 2 Sneak Peek http://t.co/hd4LwDOy Top 5 security Myths about Linux; and their realities http://t.co/zO1LgHST About Us Advertising Sitemap Privacy Contact Us Hire Us Copyright © 2008-2013 Unixmen.com . Maintained by Unixmen . /* */ jQuery(document).on('ready post-load', easy_fancybox_handler ); http://www.w3-edge.com/wordpress-plugins/ Page Caching using apc Database Caching 3/186 queries in 0.035 seconds using apc Content Delivery Network via 180016988.r.cdn77.net Served from: www.unixmen.com @ 2013-09-25 01:38:14 by W3 Total Cache

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  • Php template caching design

    - by Thomas
    Hello to all, I want to include caching in my app design. Caching templates for starters. The design I have used so far is very modular. I have created an ORM implementation for all my tables and each table is represented by the corresponding class. All the requests are handled by one controller which routes them to the appropriate webmethod functions. I am using a template class for handling UI parts. What I have in mind for caching includes the implementation of a separate Cache class for handling caching with the flexibility to either store in files, apc or memcache. Right now I am testing with file caching. Some thoughts Should I include the logic of checking for cached versions in the Template class or in the webmethods which handle the incoming requests and which eventually call the Template class. In the first case, things are pretty simple as I will not have to change anything more than pass the template class an extra argument (whether to load from cache or not). In the second case however, I am thinking of checking for a cached version immediately in the webmethod and if found return it. This will save all the processing done until the logic reaches the template (first case senario). Both senarios however, rely on an accurate mechanism of invalidating caches, which brings as to Invalidating caches As I see it (and you can add your input freely) a template cached file, becomes invalidate if: a. the expiration set, is reached. b. the template file itself is updated (ie by the developer when adding a new line) c. the webmethod that handles the request changes (ie the developer adds/deletes something in the code) d. content coming from the db and ending in the template file is modified I am thinking of storing a json encoded array inside the cached file. The first value will be the expiration timestamp of the cache. The second value will be the modification time of the php file with the code handling the request (to cope with option c above) The third will be the content itself The validation process I am considering, according to the above senarios, is: a. If the expiration of the cached file (stored in the array) is reached, delete the cache file b. if the cached file's mod time is smaller than the template's skeleton file mod time, delete the cached file c. if the mod time of the php file is greated than the one stored in the cache, delete the cached file. d. This is tricky. In the ORM implementation I ahve added event handlers (which fire when adding, updating, deleting objects). I could delete the cache file every time an object thatprovides content to the template, is modified. The problem is how to keep track which cached files correpond to each schema object. Take this example, a user has his shortprofile page and a full profile page (2 templates) These templates can be cached. Now, every time the user modifies his profile, the event handler would need to know which templates or cached files correspond to the User, so that these files can be deleted. I could store them in the db but I am looking for a beter approach

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  • C#/WPF - RoutedEvent in WPF class that isn't a UIElement

    - by Andreas
    I have a class that needs to notify that something significant has occured. The class is in a WPF-project, even though this specific class, is lookless (and doesn't inherit from UIElement, neither directly or indirectly). Normally, I just register a RoutedEvent to get this functionality but as this class neither has AddHandler nor RemoveHandler, I can't get it to work. Anyone knows of another way of get the RoutedEvent behaviour?

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