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  • How to model has_many with polymorphism?

    - by Daniel Abrahamsson
    I've run into a situation that I am not quite sure how to model. Suppose I have a User class, and a user has many services. However, these services are quite different, for example a MailService and a BackupService, so single table inheritance won't do. Instead, I am thinking of using polymorphic associations together with an abstract base class: class User < ActiveRecord::Base has_many :services end class Service < ActiveRecord::Base validates_presence_of :user_id, :implementation_id, :implementation_type belongs_to :user belongs_to :implementation, :polymorphic = true delegate :common_service_method, :name, :to => :implementation end #Base class for service implementations class ServiceImplementation < ActiveRecord::Base validates_presence_of :user_id, :on => :create has_one :service, :as => :implementation has_one :user, :through => :service after_create :create_service_record #Tell Rails this class does not use a table. def self.abstract_class? true end #Default name implementation. def name self.class.name end protected #Sets up a service object def create_service_record service = Service.new(:user_id => user_id) service.implementation = self service.save! end end class MailService < ServiceImplementation #validations, etc... def common_service_method puts "MailService implementation of common service method" end end #Example usage MailService.create(..., :user_id => user.id) BackupService.create(...., :user_id => user.id) user.services.each do |s| puts "#{user.name} is using #{s.name}" end #Daniel is using MailService, Daniel is using BackupService So, is this the best solution? Or even a good one? How have you solved this kind of problem?

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  • How do I integrate GUI elements from different classes at runtime?

    - by thefourthdoctor
    I'm trying to "future-proof" an application that I'm writing by splitting out those elements that are likely to change over time. In my application I need to be able to adapt to changes in the output format (e.g. today I output to a CSV file, in the future I may need to output directly to a SQL Server database, or to a web service, etc.). I'm handling this by defining an abstract class ("OutputProvider") that I will subclass for each individual case. The one aspect of this that has me stumped is how to provide a configuration GUI that is specific to each concrete class. I have a settings dialog with a tab for output configuration. On that tab I intend to provide a drop-down to select the provider and a JPanel beneath it to hold the contents of the provider-specific GUI. How do I get the right GUI in that panel at runtime and have it behave correctly with respect to events? Also, a bonus would be if there was a way to do this such that in order to add support for new providers I could simply provide a new jar or class file to be dropped in a specific folder and the application could pick that up at startup. I'm using NetBeans and Swing.

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  • Fluent NHibernate Repository with subclasses

    - by reallyJim
    Having some difficulty understanding the best way to implement subclasses with a generic repository using Fluent NHibernate. I have a base class and two subclasses, say: public abstract class Person { public virtual int PersonId { get; set; } public virtual string FirstName { get; set; } public virtual string LastName { get; set; } } public class Student : Person { public virtual decimal GPA { get; set; } } public class Teacher : Person { public virtual decimal Salary { get; set; } } My Mappings are as follows: public class PersonMap : ClassMap { public PersonMap() { Table("Persons"); Id(x => x.PersonId).GeneratedBy.Identity(); Map(x => x.FirstName); Map(x => x.LastName); } } public class StudentMap : SubclassMap<Student> { public StudentMap() { Table("Students"); KeyColumn("PersonId"); Map(x => x.GPA); } } public class TeacherMap : SubclassMap<Teacher> { public TeacherMap() { Table("Teachers"); KeyColumn("PersonId"); Map(x => x.Salary); } } I use a generic repository to save/retreive/update the entities, and it works great--provided I'm working with Repository--where I already know that I'm working with students or working with teachers. The problem I run into is this: What happens when I have an ID, and need to determine the TYPE of person? If a user comes to my site as PersonId = 23, how do I go about figuring out which type of person it is?

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  • What would be the light way to render a JSP page without an App/Web Server

    - by kolrie
    First, some background: I will have to work on code for a JSP that will demand a lot of code fixing and testing. This JSP will receive a structure of given objects, and render it according to a couple of rules. What I would like to do, is to write a "Test Server" that would read some mock data out of a fixtures file, and mock those objects into a factory that would be used by the JSP in question. The target App Server is WebSphere and I would like to code, change, code in order to test appropriate HTML rendering. I have done something similar on the past, but the JSP part was just calling a method on a rendering object, so I created an Ad Hoc HTTP server that would read the fixture files, parse it and render HTML. All I had to do was run it inside RAD, change the HTML code and hit F5. So question pretty much goes down to: Is there any stand alone library or lightweight server (I thought of Jetty) that would take a JSP, and given the correct contexts (Request, Response, Session, etc.) render the proper HTML?

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  • EF Many-to-many dbset.Include in DAL on GenericRepository

    - by Bryant
    I can't get the QueryObjectGraph to add INCLUDE child tables if my life depended on it...what am I missing? Stuck for third day on something that should be simple :-/ DAL: public abstract class RepositoryBase<T> where T : class { private MyLPL2Context dataContext; private readonly IDbSet<T> dbset; protected RepositoryBase(IDatabaseFactory databaseFactory) { DatabaseFactory = databaseFactory; dbset = DataContext.Set<T>(); DataContext.Configuration.LazyLoadingEnabled = true; } protected IDatabaseFactory DatabaseFactory { get; private set; } protected MyLPL2Context DataContext { get { return dataContext ?? (dataContext = DatabaseFactory.Get()); } } public IQueryable<T> QueryObjectGraph(Expression<Func<T, bool>> filter, params string[] children) { foreach (var child in children) { dbset.Include(child); } return dbset.Where(filter); } ... DAL repositories public interface IBreed_TranslatedSqlRepository : ISqlRepository<Breed_Translated> { } public class Breed_TranslatedSqlRepository : RepositoryBase<Breed_Translated>, IBreed_TranslatedSqlRepository { public Breed_TranslatedSqlRepository(IDatabaseFactory databaseFactory) : base(databaseFactory) {} } BLL Repo: public IQueryable<Breed_Translated> QueryObjectGraph(Expression<Func<Breed_Translated, bool>> filter, params string[] children) { return _r.QueryObjectGraph(filter, children); } Controller: var breeds1 = _breedTranslatedRepository .QueryObjectGraph(b => b.Culture == culture, new string[] { "AnimalType_Breed" }) .ToList(); I can't get to Breed.AnimalType_Breed.AnimalTypeId ..I can drill as far as Breed.AnimalType_Breed then the intelisense expects an expression? Cues if any, DB Tables: bold is many-to-many Breed, Breed_Translated, AnimalType_Breed, AnimalType, ...

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  • .Net lambda expression-- where did this parameter come from?

    - by larryq
    I'm a lambda newbie, so if I'm missing vital information in my description please tell me. I'll keep the example as simple as possible. I'm going over someone else's code and they have one class inheriting from another. Here's the derived class first, along with the lambda expression I'm having trouble understanding: class SampleViewModel : ViewModelBase { private ICustomerStorage storage = ModelFactory<ICustomerStorage>.Create(); public ICustomer CurrentCustomer { get { return (ICustomer)GetValue(CurrentCustomerProperty); } set { SetValue(CurrentCustomerProperty, value); } } private int quantitySaved; public int QuantitySaved { get { return quantitySaved; } set { if (quantitySaved != value) { quantitySaved = value; NotifyPropertyChanged(p => QuantitySaved); //where does 'p' come from? } } } public static readonly DependencyProperty CurrentCustomerProperty; static SampleViewModel() { CurrentCustomerProperty = DependencyProperty.Register("CurrentCustomer", typeof(ICustomer), typeof(SampleViewModel), new UIPropertyMetadata(ModelFactory<ICustomer>.Create())); } //more method definitions follow.. Note the call to NotifyPropertyChanged(p => QuantitySaved) bit above. I don't understand where the "p" is coming from. Here's the base class: public abstract class ViewModelBase : DependencyObject, INotifyPropertyChanged, IXtremeMvvmViewModel { public event PropertyChangedEventHandler PropertyChanged; protected virtual void NotifyPropertyChanged<T>(Expression<Func<ViewModelBase, T>> property) { MvvmHelper.NotifyPropertyChanged(property, PropertyChanged); } } There's a lot in there that's not germane to the question I'm sure, but I wanted to err on the side of inclusiveness. The problem is, I don't understand where the 'p' parameter is coming from, and how the compiler knows to (evidently?) fill in a type value of ViewModelBase from thin air? For fun I changed the code from 'p' to 'this', since SampleViewModel inherits from ViewModelBase, but I was met with a series of compiler errors, the first one of which statedInvalid expression term '=>' This confused me a bit since I thought that would work. Can anyone explain what's happening here?

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  • How do i add a new object with suds?

    - by Jerome
    I'm trying to use suds but have so far been unsuccessful at figuring this out. Hopefully it's something simple that i'm missing. Any help would be highly appreciated. This is supposed to be the raw soap message that i need to achieve: <soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:api="http://api.service.apimember.soapservice.com/"> <soapenv:Header/> <soapenv:Body> <api:insertOrUpdateMemberByObj> <token>t67GFCygjhkjyUy8y9hkjhlkjhuii</token> <member> <dynContent> <entry> <key>FIRSTNAME</key> <value>hhhhbbbbb</value> </entry> </dynContent> <email>[email protected]</email> </member> </api:insertOrUpdateMemberByObj> </soapenv:Body> </soapenv:Envelope> So i use suds to create the member object: member = client.factory.create('member') produces: (apiMember){ attributes = (attributes){ entry[] = <empty> } } How exactly do i append an 'entry'? I try this: member.attributes.entry.append({'key':'FIRSTNAME','value':'test'}) and that produces this: (apiMember){ attributes = (attributes){ entry[] = { value = "test" key = "FIRSTNAME" }, } } However, what i actually need is: (apiMember){ attributes = (attributes){ entry[] = (entry) { value = "test" key = "FIRSTNAME" }, } } How do i achieve this?

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  • DRYing out implementation of ICloneable in several classes

    - by Sarah Vessels
    I have several different classes that I want to be cloneable: GenericRow, GenericRows, ParticularRow, and ParticularRows. There is the following class hierarchy: GenericRow is the parent of ParticularRow, and GenericRows is the parent of ParticularRows. Each class implements ICloneable because I want to be able to create deep copies of instances of each. I find myself writing the exact same code for Clone() in each class: object ICloneable.Clone() { object clone; using (var stream = new MemoryStream()) { var formatter = new BinaryFormatter(); // Serialize this object formatter.Serialize(stream, this); stream.Position = 0; // Deserialize to another object clone = formatter.Deserialize(stream); } return clone; } I then provide a convenience wrapper method, for example in GenericRows: public GenericRows Clone() { return (GenericRows)((ICloneable)this).Clone(); } I am fine with the convenience wrapper methods looking about the same in each class because it's very little code and it does differ from class to class by return type, cast, etc. However, ICloneable.Clone() is identical in all four classes. Can I abstract this somehow so it is only defined in one place? My concern was that if I made some utility class/object extension method, it would not correctly make a deep copy of the particular instance I want copied. Is this a good idea anyway?

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  • JPA 2.0 Provider Hibernate

    - by Rooh
    I have very strange problem we are using jpa 2.0 with hibernate annotations based Database generated through JPA DDL is true and MySQL as Database; i will provide some reference classes and then my porblem. @MappedSuperclass public abstract class Common implements serializable{ @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "id", updatable = false) private Long id; @ManyToOne @JoinColumn private Address address; //with all getter and setters //as well equal and hashCode } @Entity public class Parent extends Common{ private String name; @OneToMany(cascade = {CascadeType.MERGE,CascadeType.PERSIST}, mappedBy = "parent") private List<Child> child; //setters and rest of class } @Entity public class Child extends Common{ //some properties with getter/setters } @Entity public class Address implements Serializable{ @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "id", updatable = false) private Long id; private String street; //rest of class with get/setter } as in code you can see that parents and child classes extends Common class so both have address property and id , the problem occurs when change the address refference in parent class it reflect same change in all child objects in list and if change address refference in child class then on merge it will change address refference of parent as well i am not able to figure out is it is problem of jpa or hibernate

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  • Keeping updated with the latest technologies.

    - by Prashanth
    I am a software developer and I have been programming since the past six years. I simply love the mental challenge involved in trying to come up with solutions to hard problems, reading up programming literature, blogs by prominent developers and so on. I work on Microsoft platform and I have trouble keeping up with the pace at which various frameworks are rolled out. Remoting,WCF,ASP.NET,ASP.NET MVC, LINQ, WPF, WWF, OSLO, ADO.NET data services, DSL tools etc etc. Even understanding all these frameworks at an abstract level and see how they are all tied up with MS vision itself is a major hurdle. Now when you add other non microsoft technologies, programming languages etc to the equation, I wonder how do people manage? Given that there are only 24 hours in a day, how does one keep himself updated about so many technology changes that happen everyday? My question is , is it even worth doing that? The thing is, I am also interested in other fields such as literature, science. I try my best to at least gain a superficial understanding of what is happening in other fields of my interest and don't want to give up on that :)

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  • Spring, Need to use a a bean declared in a ApplicationContextFactory servlet, in a DispatcherServlet

    - by Ernest
    Hello, i have a web.xml with these 2 servlet: <servlet> <servlet-name>ApplicationContextFactory</servlet-name> <servlet-class>com.bamboo.common.factory.ApplicationContextFactory</servlet-class> <load-on-startup>1</load-on-startup> </servlet> AND <servlet> <servlet-name>dispatcher</servlet-name> <servlet-class> org.springframework.web.servlet.DispatcherServlet </servlet-class> <load-on-startup>1</load-on-startup> </servlet> I need to use these bean declared on the ApplicationContextFactory: <bean id="**catalogFacadeTarget**" class="com.bamboo.catW3.business.impl.CatalogFacadeImpl"> <property name="categoryDAO"><ref local="categoryDAOTarget"/></property> <property name="containerDAO"><ref local="containerDAOTarget"/></property> <property name="productDAO"><ref local="productDAOTarget"/></property> <property name="productOptionDAO"><ref local="productOptionDAOTarget"/></property> <property name="productStatusDAO"><ref local="productStatusDAOTarget"/></property> <property name="userDAO"><ref local="userDAOTarget"/></property> </bean> in the dispatcher-servlet like this: <bean name="welcome" class="com.bamboo.catW3.business.impl.Welcome"> <property name="successView"> <value>welcome</value> </property> <property name="catalogFacadeImpl"><ref local="**categoryDAOTarget**"/> </property> </bean> Is it posible some how? Thank you!

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  • dll's loaded through reflection

    - by Seattle Leonard
    Ok, I got a strange one here and I want to know if any of you have ever run accross anything like it. So I've got this web app that loads up a bunch of dll's through reflection. Basically it looks for Types that are derived from certain abstract types and adds them to the list of things it can make. Here's the weird part. While developing there is never a problem. When installing it, there is never a problem to start with. Then, at a seemingly random time, the application breaks while trying to find all the types. I've had 2 sites sitting side by side and one worked while the other did not, and they were configured exactly(and I mean exactly) the same. IISRESET's never helped, but this did: I simply moved all the dll's out of the bin directory then moved them back. That's right I just moved them out of the bin directory then put them right back where they came from and everything worked fine. Any ideas?

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  • NHibernate unintential lazy property loading

    - by chiccodoro
    I introduced a mapping for a business object which has (among others) a property called "Name": public class Foo : BusinessObjectBase { ... public virtual string Name { get; set; } } For some reason, when I fetch "Foo" objects, NHibernate seems to apply lazy property loading (for simple properties, not associations): The following code piece generates n+1 SQL statements, whereof the first only fetches the ids, and the remaining n fetch the Name for each record: ISession session = ...IQuery query = session.CreateQuery(queryString); ITransaction tx = session.BeginTransaction(); List<Foo> result = new List<Foo>(); foreach (Foo foo in query.Enumerable()) { result.Add(foo); } tx.Commit(); session.Close(); produces: NHibernate: select foo0_.FOO_ID as col_0_0_ from V1_FOO foo0_ NHibernate: SELECT foo0_.FOO_ID as FOO1_2_0_, foo0_.NAME as NAME2_0_ FROM V1_FOO foo0_ WHERE foo0_.FOO_ID=:p0;:p0 = 81 NHibernate: SELECT foo0_.FOO_ID as FOO1_2_0_, foo0_.NAME as NAME2_0_ FROM V1_FOO foo0_ WHERE foo0_.FOO_ID=:p0;:p0 = 36470 NHibernate: SELECT foo0_.FOO_ID as FOO1_2_0_, foo0_.NAME as NAME2_0_ FROM V1_FOO foo0_ WHERE foo0_.FOO_ID=:p0;:p0 = 36473 Similarly, the following code leads to a LazyLoadingException after session is closed: ISession session = ... ITransaction tx = session.BeginTransaction(); Foo result = session.Load<Foo>(id); tx.Commit(); session.Close(); Console.WriteLine(result.Name); Following this post, "lazy properties ... is rarely an important feature to enable ... (and) in Hibernate 3, is disabled by default." So what am I doing wrong? I managed to work around the LazyLoadingException by doing a NHibernateUtil.Initialize(foo) but the even worse part are the n+1 sql statements which bring my application to its knees. This is how the mapping looks like: <class name="Foo" table="V1_FOO"> ... <property name="Name" column="NAME"/> </class> BTW: The abstract "BusinessObjectBase" base class encapsulates the ID property which serves as the internal identifier.

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  • adding an uncertain number of fields using javascript

    - by user306472
    I'm new to javascript and a novice programmer, so this might be a really easy question to answer. I would like to loop over the values of x number of fields and add them up to display the sum in a final field. I can perform this function if I explicitly call each field, but I want to abstract this so I can deal with a flexible number of fields. Here's example code I've come up with (that's not working for me). Where am I going wrong? <html> <head> <script type="text/javascript"> function startAdd(){ interval = setInterval("addfields()",1); } function addfields(){ a = document.addition.total.value; b = getElementByTagName("sum").value; for (i=0; i<=b.length; i++){ a+=i; } return a; } function stopAdd(){ clearInterval(interval); } </script> </head> <body> <form name="addition"> <input type="text" name="sum" onFocus="startAdd();" onBlur="stopAdd;"> + <input type="text" name="sum" onFocus="startAdd();" onBlur="stopAdd;"> = <input type="text" name ="total"> </form> </body> </html>

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  • How can you transform a set of numbers into mostly whole ones?

    - by Alice
    Small amount of background: I am working on a converter that bridges between a map maker (Tiled) that outputs in XML, and an engine (Angel2D) that inputs lua tables. Most of this is straight forward However, Tiled outputs in pixel offsets (integers of absolute values), while Angel2D inputs OpenGL units (floats of relative values); a conversion factor between these two is needed (for example, 32px = 1gu). Since OpenGL units are abstract, and the camera can zoom in or out if the objects are too small or big, the actual conversion factor isn't important; I could use a random number, and the user would merely have to zoom in or out. But it would be best if the conversion factor was selected such that most numbers outputted were small and whole (or fractions of small whole numbers), because that makes it easier to work with (and the whole point of the OpenGL units is that they are easy to work with). How would I find such a conversion factor reliably? My first attempt was to use the smallest number given; this resulted in no fractions below 1, but often lead to lots of decimal places where the factors didn't line up. Then I tried the mode of the sequence, which lead to the largest number of 1's possible, but often lead to very long floats for background images. My current approach gets the GCD of the whole sequence, which, when it works, works great, but can easily be thrown off course by a single bad apple. Note that while I could easily just pass the numbers I am given along, or pick some fixed factor, or use one of the conversions I specified above, I am looking for a method to reliably scale this list of integers to small, whole numbers or simple fractions, because this would most likely be unsurprising to the end user; this is not a one off conversion. The end users tend to use 1.0 as their "base" for manipulations (because it's simple and obvious), so it would make more sense for the sizes of entities to cluster around this.

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  • Auto increment with a Unit Of Work

    - by Derick
    Context I'm building a persistence layer to abstract different types of databases that I'll be needing. On the relational part I have mySQL, Oracle and PostgreSQL. Let's take the following simplified MySQL tables: CREATE TABLE Contact ( ID varchar(15), NAME varchar(30) ); CREATE TABLE Address ( ID varchar(15), CONTACT_ID varchar(15), NAME varchar(50) ); I use code to generate system specific alpha numeric unique ID's fitting 15 chars in this case. Thus, if I insert a Contact record with it's Addresses I have my generated Contact.ID and Address.CONTACT_IDs before committing. I've created a Unit of Work (amongst others) as per Martin Fowler's patterns to add transaction support. I'm using a key based Identity Map in the UoW to track the changed records in memory. It works like a charm for the scenario above, all pretty standard stuff so far. The question scenario comes in when I have a database that is not under my control and the ID fields are auto-increment (or in Oracle sequences). In this case I do not have the db generated Contact.ID beforehand, so when I create my Address I do not have a value for Address.CONTACT_ID. The transaction has not been started on the DB session since all is kept in the Identity Map in memory. Question: What is a good approach to address this? (Avoiding unnecessary db round trips) Some ideas: Retrieve the last ID: I can do a call to the database to retrieve the last Id like: SELECT Auto_increment FROM information_schema.tables WHERE table_name='Contact'; But this is MySQL specific and probably something similar can be done for the other databases. If do this then would need to do the 1st insert, get the ID and then update the children (Address.CONTACT_IDs) – all in the current transaction context.

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  • How to specialize a type parameterized argument to multiple different types for in Scala?

    - by jmount
    I need a back-check (please). In an article ( http://www.win-vector.com/blog/2010/06/automatic-differentiation-with-scala/ ) I just wrote I stated that it is my belief in Scala that you can not specify a function that takes an argument that is itself a function with an unbound type parameter. What I mean is you can write: def g(f:Array[Double]=>Double,Array[Double]):Double but you can not write something like: def g(f[Y]:Array[Y]=>Double,Array[Double]):Double because Y is not known. The intended use is that inside g() I will specialize fY to multiple different types at different times. You can write: def g[Y](f:Array[Y]=>Double,Array[Double]):Double but then f() is of a single type per call to g() (which is exactly what we do not want). However, you can get all of the equivalent functionality by using a trait extension instead insisting on passing around a function. What I advocated in my article was: 1) Creating a trait that imitates the structure of Scala's Function1 trait. Something like: abstract trait VectorFN { def apply[Y](x:Array[Y]):Y } 2) declaring def g(f:VectorFN,Double):Double (using the trait is the type). This works (people here on StackOverflow helped me find it, and I am happy with it)- but am I mis-representing Scala by missing an even better solution?

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  • How can I implement CRUD operations in a base class for an entity framework app?

    - by hminaya
    I'm working a simple EF/MVC app and I'm trying to implement some Repositories to handle my entities. I've set up a BaseObject Class and a IBaseRepository Interface to handle the most basic operations so I don't have to repeat myself each time: public abstract class BaseObject<T> { public XA.Model.Entities.XAEntities db; public BaseObject() { db = new Entities.XAEntities(); } public BaseObject(Entities.XAEntities cont) { db = cont; } public void Delete(T entity) { db.DeleteObject(entity); db.SaveChanges(); } public void Update(T entity) { db.AcceptAllChanges(); db.SaveChanges(); } } public interface IBaseRepository<T> { void Add(T entity); T GetById(int id); IQueryable<T> GetAll(); } But then I find myself having to implement 3 basic methods in every Repository ( Add, GetById & GetAll): public class AgencyRepository : Framework.BaseObject<Agency>, Framework.IBaseRepository<Agency> { public void Add(Agency entity) { db.Companies.AddObject(entity); db.SaveChanges(); } public Agency GetById(int id) { return db.Companies.OfType<Agency>().FirstOrDefault(x => x.Id == id); } public IQueryable<Agency> GetAll() { var agn = from a in db.Companies.OfType<Agency>() select a; return agn; } } How can I get these into my BaseObject Class so I won't run in conflict with DRY.

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  • What OOP pattern to use when only adding new methods, not data?

    - by Jonathon Reinhart
    Hello eveyone... In my app, I have deal with several different "parameters", which derive from IParameter interface, and also ParamBase abstract base class. I currently have two different parameter types, call them FooParameter and BarParameter, which both derive from ParamBase. Obviously, I can treat them both as IParameters when I need to deal with them generically, or detect their specific type when I need to handle their specific functionality. My question lies in specific FooParameters. I currently have a few specific ones with their own classes which derive from FooParameter, we'll call them FP12, FP13, FP14, etc. These all have certain characteristics, which make me treat them differently in the UI. (Most have names associated with the individual bits, or ranges of bits). Note that these specific, derived FP's have no additional data associated with them, only properties (which refer to the same data in different ways) or methods. Now, I'd like to keep all of these parameters in a Dictionary<String, IParameter> for easy generic access. The problem is, if I want to refer to a specific one with the special GUI functions, I can't write: FP12 fp12 = (FP12)paramList["FP12"] because you can't downcast to a derived type (rightfully so). But in my case, I didn't add any data, so the cast would theoretically work. What type of programming model should I be using instead? Thanks!

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  • Javascript CS-PRNG - 64-bit random

    - by Jack
    Hi, I need to generate a cryptographically secure 64-bit unsigned random integer in Javascript. The first problem is that Javascript only allows 64-bit signed integers, so 9223372036854775808 is the biggest supported integer without going into floating point use I think? To fix this I can use a big number library, no problem. My Method: var randNum = SHA256( randBigInt(128, 0) ) % 2^64; Where SHA256() is a secure hash function and randBigInt() is defined below as a non-crypto PRNG, im giving it a 128bit seed so brute force shouldn't be a problem. randBigInt(n,s) //return an n-bit random BigInt (n>=1). If s=1, then the most significant of those n bits is set to 1. Is this a secure method to generate a cryptographically secure 64-bit random int? And importantly does taking the 2^64 mod guarantee 100% I have a 64-bit number? An abstract example, say this number is prime (it isn't i know), I will use it in the Galois Field [2^p], where p must be 64bits so that every possible 1-63bit number is a field element. In this query, my random int must be larger than any 63-bit number. And Im not sure im correct in taking the 2^64 mod of a 256bit hash output. Thanks (hope that makes sense)

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  • Which is the better C# class design for dealing with read+write versus readonly

    - by DanM
    I'm contemplating two different class designs for handling a situation where some repositories are read-only while others are read-write. (I don't foresee any need to a write-only repository.) Class Design 1 -- provide all functionality in a base class, then expose applicable functionality publicly in sub classes public abstract class RepositoryBase { protected virtual void SelectBase() { // implementation... } protected virtual void InsertBase() { // implementation... } protected virtual void UpdateBase() { // implementation... } protected virtual void DeleteBase() { // implementation... } } public class ReadOnlyRepository : RepositoryBase { public void Select() { SelectBase(); } } public class ReadWriteRepository : RepositoryBase { public void Select() { SelectBase(); } public void Insert() { InsertBase(); } public void Update() { UpdateBase(); } public void Delete() { DeleteBase(); } } Class Design 2 - read-write class inherits from read-only class public class ReadOnlyRepository { public void Select() { // implementation... } } public class ReadWriteRepository : ReadOnlyRepository { public void Insert() { // implementation... } public void Update() { // implementation... } public void Delete() { // implementation... } } Is one of these designs clearly stronger than the other? If so, which one and why? P.S. If this sounds like a homework question, it's not, but feel free to use it as one if you want :)

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  • Applying the Decorator Pattern to Forms

    - by devoured elysium
    I am trying to apply the Decorator Design Pattern to the following situation: I have 3 different kind of forms: Green, Yellow, Red. Now, each of those forms can have different set of attributes. They can have a minimize box disabled, a maximized box disabled and they can be always on top. I tried to model this the following way: Form <---------------------------------------FormDecorator /\ /\ |---------|-----------| |----------------------|-----------------| GreenForm YellowForm RedForm MinimizeButtonDisabled MaximizedButtonDisabled AlwaysOnTop Here is my GreenForm code: public class GreenForm : Form { public GreenForm() { this.BackColor = Color.GreenYellow; } public override sealed Color BackColor { get { return base.BackColor; } set { base.BackColor = value; } } } FormDecorator: public abstract class FormDecorator : Form { private Form _decoratorForm; protected FormDecorator(Form decoratorForm) { this._decoratorForm = decoratorForm; } } and finally NoMaximizeDecorator: public class NoMaximizeDecorator : FormDecorator { public NoMaximizeDecorator(Form decoratorForm) : base(decoratorForm) { this.MaximizeBox = false; } } So here is the running code: static void Main() { Application.EnableVisualStyles(); Application.SetCompatibleTextRenderingDefault(false); Application.Run(CreateForm()); } static Form CreateForm() { Form form = new GreenForm(); form = new NoMaximizeDecorator(form); form = new NoMinimizeDecorator(form); return form; } The problem is that I get a form that isn't green and that still allows me to maximize it. It is only taking in consideration the NoMinimizeDecorator form. I do comprehend why this happens but I'm having trouble understanding how to make this work with this Pattern. I know probably there are better ways of achieving what I want. I made this example as an attempt to apply the Decorator Pattern to something. Maybe this wasn't the best pattern I could have used(if one, at all) to this kind of scenario. Is there any other pattern more suitable than the Decorator to accomplish this? Am I doing something wrong when trying to implement the Decorator Pattern? Thanks

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  • TabHost disappears after locking the phone and reopening it:

    - by Emil Adz
    I have a weird issue with my TabHost in my FragmentActivity that contains a ViewPager. The problem is that when I close my phone (press the power button) while I use my application, and then I turn back the phone and my application gets reopened, at this point my TabHost is missing. So the closing of my phone is causes the TabHost to disappear. My guess would be that I need to save my tabHost state in the saveInstanceState object, and restore it in onResume I only have no idea how it's done. here is my code for the FragmentActivity: public class TabsViewPagerFragmentActivity extends FragmentActivity implements ViewPager.OnPageChangeListener, TabHost.OnTabChangeListener { static final String TAG = TabsViewPagerFragmentActivity.class.getSimpleName(); private TabHost mTabHost; private ViewPager mViewPager; private HashMap<String, TabInfo> mapTabInfo; public ViewPagerAdapter mPagerAdapter; private TextView tvReportName, tvTabTitle; private Button bBackToParameters; private Dialog progressDialog; private SGRaportManagerAppObj application; private int numberOfTabs = 0; private Display display; public static final int POPUP_MARGIN = 6; LeftSideMenu leftSideMenu; public void NotifyTabActivityViewPagerAdapter() { mPagerAdapter.notifyDataSetChanged(); } public ViewPagerAdapter getTabActivityViewPagerAdapter() { return mPagerAdapter; } public ViewPager getTabActivityViewPager() { return mViewPager; } public void setCurrentTabTitle (String title) { tvTabTitle.setText(title); Log.d(TAG, "set tab title from activity: "+title); } /** * Maintains extrinsic info of a tab's construct */ private class TabInfo { private String tag; private Class<?> clss; private Bundle args; private Fragment fragment; TabInfo(String tag, Class<?> clazz, Bundle args) { this.tag = tag; this.clss = clazz; this.args = args; } } /** * A simple factory that returns dummy views to the Tabhost */ class TabFactory implements TabContentFactory { private final Context mContext; /** * @param context */ public TabFactory(Context context) { mContext = context; } /** (non-Javadoc) * @see android.widget.TabHost.TabContentFactory#createTabContent(java.lang.String) */ public View createTabContent(String tag) { View v = new View(mContext); v.setMinimumWidth(0); v.setMinimumHeight(0); return v; } } /** (non-Javadoc) * @see android.support.v4.app.FragmentActivity#onCreate(android.os.Bundle) */ public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); application = SGRaportManagerAppObj.getInstance(); display = ((WindowManager)getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay(); // Inflate the layout setContentView(R.layout.tabs_screen_activity_layout); tvTabTitle = (TextView) findViewById(R.id.tvTabName); tvReportName = (TextView)findViewById(R.id.tvReportName); tvReportName.setText(application.currentReport.getName()+ " - "); bBackToParameters = (Button) findViewById(R.id.bBackToParameters); leftSideMenu = (LeftSideMenu) findViewById(R.id.leftSideMenu); applyOnClickListenerToLeftSideMenu(); findViewById(R.id.showLeftMenuButton).setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { Display d = ((WindowManager)getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay(); int width = d.getWidth(); View panel = findViewById(R.id.leftSideMenu); View appPanel = findViewById(R.id.appLayout); if (panel.getVisibility() == View.GONE){ appPanel.setLayoutParams(new LinearLayout.LayoutParams(width, LayoutParams.FILL_PARENT)); panel.setVisibility(View.VISIBLE); applyOnClickListenerToLeftSideMenu(); }else{ ToggleButton button = (ToggleButton) findViewById(R.id.showLeftMenuButton); button.setChecked(false); panel.setVisibility(View.GONE); } } }); // Initialise the TabHost progressDialog = DialogUtils.createProgressDialog(this, this.getString(R.string.populating_view_pager)); progressDialog.show(); if (SGRaportManagerAppObj.getInstance().parametersRepository.getParametersRepository().size() == 0) { bBackToParameters.setText(R.string.back_to_report_list); } this.initialiseTabHost(savedInstanceState); if (savedInstanceState != null) { mTabHost.setCurrentTabByTag(savedInstanceState.getString("tab")); //set the tab as per the saved state } // Intialise ViewPager this.intialiseViewPager(); progressDialog.dismiss(); } /** (non-Javadoc) * @see android.support.v4.app.FragmentActivity#onSaveInstanceState(android.os.Bundle) */ protected void onSaveInstanceState(Bundle outState) { outState.putString("tab", mTabHost.getCurrentTabTag()); //save the tab selected super.onSaveInstanceState(outState); } /** * Initialise ViewPager */ public void intialiseViewPager() { List<Fragment> fragments = new Vector<Fragment>(); // TabInfo tabInfo = null; if (application.getCurrentDataSource().equals(DataSource.SSRS)) { numberOfTabs = application.currentReport.getTabsList().size(); } else if (application.getCurrentDataSource().equals(DataSource.SGRDL)) { numberOfTabs = application.currentReport.getODTabsList().size(); Log.d(TAG, "CURRENT REPORT FROM VIEW PAGER: "+ application.currentReport.toString()); } Log.d(TAG,"Current Tabs number from TabsViewPager activity: " +numberOfTabs); if (application.getCurrentDataSource().equals(DataSource.SSRS)) { for (int i = 0; i < numberOfTabs; i++) { Tab tempTab = application.currentReport.getTabsList().get(i); if (tempTab.getTabTemplateId() == 7) { GridFragment gridFragment = new GridFragment(tempTab); fragments.add(gridFragment); } else if (tempTab.getTabTemplateId() == 8) { NewChartFragment chartFragment = new NewChartFragment(tempTab, this); fragments.add(chartFragment); } } } else if (application.getCurrentDataSource().equals(DataSource.SGRDL)) { for (int i = 0; i < numberOfTabs; i++) { ODTab tempTab = application.currentReport.getODTabsList().get(i); if (tempTab.getTabType().equals(ODGrid.XML_GRID_ELEMENT)) { GridFragment gridFragment = GridFragment.newInstance(tempTab.getTabId()); fragments.add(gridFragment); } else if (tempTab.getTabType().equals(ODChart.XML_CHART_ELEMENT)) { NewChartFragment chartFragment = NewChartFragment.newInstance(tempTab.getTabId()); fragments.add(chartFragment); } } } Log.d(TAG, "Current report fragments set to adapter: "+fragments.toString()); /* if (this.mPagerAdapter == null) { this.mPagerAdapter = new ViewPagerAdapter(super.getSupportFragmentManager(), fragments); } else { this.mPagerAdapter.removeAllFragments(); this.mPagerAdapter.addFragmentsListToAdapter(fragments); } */ this.mPagerAdapter = new ViewPagerAdapter(super.getSupportFragmentManager(), fragments); this.mViewPager = (ViewPager)super.findViewById(R.id.pager); // this.mViewPager.setAdapter(null); this.mViewPager.setAdapter(this.mPagerAdapter); this.mViewPager.setOffscreenPageLimit(0); this.mViewPager.setOnPageChangeListener(this); Log.d(TAG, "Adapter initialized!"); } /** * Initialise the Tab Host */ public void initialiseTabHost(Bundle args) { mTabHost = (TabHost)findViewById(android.R.id.tabhost); /* //new edit if (mTabHost.getChildCount() > 0) { mTabHost.removeAllViews(); } */ mTabHost.setup(); TabInfo tabInfo = null; mapTabInfo = new HashMap<String, TabsViewPagerFragmentActivity.TabInfo>(); if (args != null) {} else { if (application.getCurrentDataSource().equals(DataSource.SSRS)) { int numberOfTabs = application.currentReport.getTabsList().size(); for (int i = 0; i < numberOfTabs; i++) { Tab tempTab = application.currentReport.getTabsList().get(i); if (tempTab.getTabTemplateId() == 7) { //GridFragment gridFragment = new GridFragment(tempTab); TabsViewPagerFragmentActivity.AddTab(this, this.mTabHost, this.mTabHost.newTabSpec("Tab "+String.valueOf(i)).setIndicator("Tab "+String.valueOf(i)), ( tabInfo = new TabInfo("Tab "+String.valueOf(i), GridFragment.class, args))); this.mapTabInfo.put(tabInfo.tag, tabInfo); } else if (tempTab.getTabTemplateId() == 8) { TabsViewPagerFragmentActivity.AddTab(this, this.mTabHost, this.mTabHost.newTabSpec("Tab "+String.valueOf(i)).setIndicator("Tab "+String.valueOf(i)), ( tabInfo = new TabInfo("Tab "+String.valueOf(i), NewChartFragment.class, args))); this.mapTabInfo.put(tabInfo.tag, tabInfo); } } } else if (application.getCurrentDataSource().equals(DataSource.SGRDL)) { int numberOfTabs = application.currentReport.getODTabsList().size(); for (int i = 0; i < numberOfTabs; i++) { ODTab tempTab = application.currentReport.getODTabsList().get(i); // Log.d(TAG,"Crashed Tab type: "+ tempTab.getTabType()); if (tempTab.getTabType().equals(ODGrid.XML_GRID_ELEMENT)) { //GridFragment gridFragment = new GridFragment(tempTab); TabsViewPagerFragmentActivity.AddTab(this, this.mTabHost, this.mTabHost.newTabSpec("Tab "+String.valueOf(i)).setIndicator("Tab "+String.valueOf(i)), ( tabInfo = new TabInfo("Tab "+String.valueOf(i), GridFragment.class, args))); this.mapTabInfo.put(tabInfo.tag, tabInfo); } else if (tempTab.getTabType().equals(ODChart.XML_CHART_ELEMENT)) { TabsViewPagerFragmentActivity.AddTab(this, this.mTabHost, this.mTabHost.newTabSpec("Tab "+String.valueOf(i)).setIndicator("Tab "+String.valueOf(i)), ( tabInfo = new TabInfo("Tab "+String.valueOf(i), NewChartFragment.class, args))); this.mapTabInfo.put(tabInfo.tag, tabInfo); } } } } // Default to first tab //this.onTabChanged("Tab1"); // mTabHost.setOnTabChangedListener(this); } /** * Add Tab content to the Tabhost * @param activity * @param tabHost * @param tabSpec * @param clss * @param args */ private static void AddTab(TabsViewPagerFragmentActivity activity, TabHost tabHost, TabHost.TabSpec tabSpec, TabInfo tabInfo) { // Attach a Tab view factory to the spec ImageView indicator = new ImageView(activity.getBaseContext()); indicator.setPadding(10, 10, 10, 10); indicator.setImageResource(R.drawable.tab_select_icon_selector); LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT); lp.setMargins(10, 10, 10, 10); indicator.setLayoutParams(lp); tabSpec.setIndicator(indicator); tabSpec.setContent(activity.new TabFactory(activity)); tabHost.addTab(tabSpec); } /** (non-Javadoc) * @see android.widget.TabHost.OnTabChangeListener#onTabChanged(java.lang.String) */ public void onTabChanged(String tag) { //TabInfo newTab = this.mapTabInfo.get(tag); int pos = this.mTabHost.getCurrentTab(); this.mViewPager.setCurrentItem(pos); } /* (non-Javadoc) * @see android.support.v4.view.ViewPager.OnPageChangeListener#onPageScrolled(int, float, int) */ @Override public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { // TODO Auto-generated method stub } /* (non-Javadoc) * @see android.support.v4.view.ViewPager.OnPageChangeListener#onPageSelected(int) */ @Override public void onPageSelected(int position) { // TODO Auto-generated method stub this.mTabHost.setCurrentTab(position); } /* (non-Javadoc) * @see android.support.v4.view.ViewPager.OnPageChangeListener#onPageScrollStateChanged(int) */ @Override public void onPageScrollStateChanged(int state) { // TODO Auto-generated method stub } How would one save the state of the TabHost and restore it in onResume? Any help would be very appreciated.

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  • Should a developer be a coauthor to a paper presented about the application they developed?

    - by ved
    In our organization, project teams come up with a need and funding and developers are given a basic scope and are allowed to develop the solution. There is a certain degree of implementation freedom given to the developers. They drive the solution to pilot and live deployment from its inception. If the solution is presented in a conference as a technical paper/white paper what is the protocol for the list of authors: because for the most part I see the project manager's and the dev team manager's names as authors but no mention of the actual developer. Is this correct? A lot of us developers feel pretty bummed to never see our names as the coauthors. Appreciate any pointers. Answers to the FOLLOW UP questions (1) in what field of study is the paper, and what are the standards of authorship for that field? The paper is for Flood Plain Management - there is nothing on the abstract guidelines, I have called the contact person listed for comment - waiting to hear. 2) was the paper literally about the software application as your question implies, or were the software issues incidental to the topic of the paper? The paper specifically deals with a GIS Application that is used in Coastal Engineering, yes the software is not incidental, but the meat of the paper and mentioned in the Title. 2

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  • iPhone: Calling dealloc on parentViewController causes an exception

    - by arielcamus
    Hi, I'm dealing with viewDidUnload and dealloc methods and I've founded a problem when calling [super dealloc]; in parent view controller. I have a lot of view controllers with custom code which I have putted outside on a parent view controller. So, when defining my view controllers I set a reference to the super class: @interface LoginViewController : AbstractViewController Then, at the dealloc method I call the AbstractViewController dealloc method: //(Login View Controller code) - (void)dealloc { [user release]; [passwd release]; [super dealloc]; } [super dealloc] execute the following code: //(Abstract View Controller code) - (void)dealloc { [dbUtils release]; [loadingView release]; [super dealloc]; } If I simulate a memory warning on iPhone Simulator, the following exception is thrown: 2010-03-03 11:27:45.805 MyApp[71563:40b] Received simulated memory warning. 2010-03-03 11:27:45.808 MyApp[71563:40b] *** -[LoginViewController isViewLoaded]: message sent to deallocated instance 0x13b51b0 kill quit However, if I comment the [super dealloc] line in AbstractViewController the exception is not thrown and my app still running. Thank you for your help once again!

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