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  • Making OR/M loosely coupled and abstracted away from other layers.

    - by Genuine
    Hi all. In an n-tier architecture, the best place to put an object-relational mapping (OR/M) code is in the data access layer. For example, database queries and updates can be delegated to a tool like NHibernate. Yet, I'd like to keep all references to NHibernate within the data access layer and abstract dependencies away from the layers below or above it. That way, I can swap or plug in another OR/M tool (e.g. Entity Framework) or some approach (e.g. plain vanilla stored procedure calls, mock objects) without causing compile-time errors or a major overhaul of the entire application. Testability is an added bonus. Could someone please suggest a wrapper (i.e. an interface or base class) or approach that would keep OR/M loosely coupled and contained in 1 layer? Or point me to resources that would help? Thanks.

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  • Custom OData operation / customize EF model to hide join table in many-to-many relationship

    - by AC
    I've got a data model that has two tables with a join table for a many to many relationship & creating an OData service to expose the data for CRUD ops in a Silverlight app. What I'd like to do is abstract the join table from the service. I'm not sure if the best way to do this would be in the model (using EF in .NET3.5SP1) or if I should do it with a custom service operation. If I do it in the EF model (not sure how I'd do this), then the OOTB WCF Data Service stuff would make it easy to say [..]/Courses(1)/Modules ... otherwise I'd have to create a custom operation to do this. Is it possible to do this in the EF model and if so, how does that work?

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  • C#: reflection alternative for switch on enum in order to select namespace/class

    - by Am
    Hi, I have an interface named IHarvester. There are 3 implementations of that interface, each under their own namespace: Google Yahoo Bing A HarvesterManager uses the given harvester. It knows the interface and all 3 implementations. I want some way of letting the class user say in which harvester it wants to use. And in the code select that implementation, without a switch-case implementation. Can reflection save my day? Here is the code bits: // repeat for each harvester namespace Harvester.Google { public abstract class Fetcher : BaseHarvester, IInfoHarvester {...} } public enum HarvestingSource { Google, Yahoo, Bing, } class HarvesterManager { public HarvestingSource PreferedSource {get;set;} public HarvestSomthing() { switch (PreferedSource) .... // awful... } } Thanks.

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  • Using enums or a set of classes when I know I have a finite set of different options?

    - by devoured elysium
    Let's say I have defined the following class: public abstract class Event { public DateTime Time { get; protected set; } protected Event(DateTime time) { Time = time; } } What would you prefer between this: public class AsleepEvent : Event { public AsleepEvent(DateTime time) : base(time) { } } public class AwakeEvent : Event { public AwakeEvent(DateTime time) : base(time) { } } and this: public enum StateEventType { NowAwake, NowAsleep } public class StateEvent : Event { protected StateEventType stateType; public MealEvent(DateTime time, StateEventType stateType) : base(time) { stateType = stateType; } } and why? I am generally more inclined to the first option, but I can't explain why. Is it totally the same or are any advantages in using one instead of the other? Maybe with the first method its easier to add more "states", altough in this case I am 100% sure I will only want two states: now awake, and now asleep (they signal the moments when one awakes and one falls asleep).

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  • C#: why Base class is allowed to implement an interface contract without inheriting from it?

    - by etarassov
    I've stumbled upon this "feature" of C# - the base class that implements interface methods does not have to derive from it. Example: public interface IContract { void Func(); } // Note that Base does **not** derive from IContract public abstract class Base { public void Func() { Console.WriteLine("Base.Func"); } } // Note that Derived does *not* provide implementation for IContract public class Derived : Base, IContract { } What happens is that Derived magically picks-up a public method Base.Func and decides that it will implement IContract.Func. What is the reason behind this magic? IMHO: this "quasi-implementation" feature is very-unintuitive and make code-inspection much harder. What do you think?

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  • What is the initiating actor for the usecase shown here

    - by Illep
    I am new to drawing use case and writing use case descriptions. I have an Actor called User , an abstract usecase called Work Type and another use case called Manager. The usecase Manager has a generalized relationship with the Work Type use case. I'm now writing the use case description for Manager use case. And what is the initiating Actor for this use case. Is it the Actor User ? or doesn't it have an initiating Actor ? Note: I only want to know the initiating Actor for the use case Manager

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  • Getting error in integrating Contacts APIs in Android 1.6 and 2.0

    - by dhaiwat
    Hi All, I have seen the BusinessCard example provide in Android examples. I am using ContactAccessor abstract class to seperate out the SDK versions. My code is running fine for 2.0 onwards, but when I am trying to build the code in Adnroid 1.6 I am getting the following errors: Build.VERSION_CODES.ECLAIR is not resolved. Getting errors in the whole class in which I have used Contacts APIs from 2.0 (say in class ContactAccessorSdk5.java). How to resolve these issues? I want to run my App on both the versions. Please help me. Regards, Dhaiwat Bhavsar.

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  • C# to Java Conversion: What is a [DefaultProperty("value")]?

    - by Shiftbit
    I do not understand how the DefaultProperty Metadata tag work or what it signifies. I've read the MSDN and went through the sample but I find it confusing. DefaultPropertyAttribute Class I've read a few blogs and they seem to refer to the indexers. I'm not sure why you would want metadata for your properties? I am coming from a Java background, perhaps a Java analogy would help. [DefaultProperty("Value")] public abstract class FOO<T> : ANY, IBAR<T> { public FOO() { } public FOO(T value) { this.Value = value; } public virtual T Value { get; set; } }

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  • .NET Forms Abstraction for WPF, Silverlight, Winforms, WebForms, etc...

    - by tyndall
    Anyone know of a project(s) that seek to abstract form definitions on level higher than WPF, Silverlight, Winforms, WebForms, etc... I'm working on a project where we are fixing up 16 somewhat simple WebForms. But we may convert (and probably will convert to WPF or Silverlight 3 to 4 months from now. I'd rather define these forms once and be done with it. I'm willing to write a small DSL to help define forms, subforms, validation, links, and popups. I'm only looking to solve this for 80% or 90% of the forms. Four are very complicated and I'm willing to hand code these. I guess I'm looking for something like what XUL had hoped to be.

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

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

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  • Magento: Why do controller action predispatch events not fire if the controller is rewritten?

    - by mattalexx
    Why do controller action predispatch events not fire if the controller is rewritten? Here is a snippet of store/app/code/core/Mage/Core/Controller/Varien/Action.php: abstract class Mage_Core_Controller_Varien_Action { // [...] public function preDispatch() { // [...] if ($this->_rewrite()) { return; // [What is the purpose if this?] } // [...] // [This is where my event needs to be firing, but this code never gets // executed because the controller is rewritten] Mage::dispatchEvent( 'controller_action_predispatch_'.$this->getFullActionName(), array('controller_action'=>$this) ); } // [...] } I don't know where to start fixing this problem. Anyone out there ever dealt with this before?

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  • Connect two daemons in python

    - by Simon
    What is the best way to connect two daemons in Python? I have daemon A and B. I'd like to receive data generated by B in A's module (maybe bidirectional). Both daemons support plugins, so I'd like to shut communication in plugins. What's the best and cross-platform way to do that? I know few mechanisms from low-level solutions - shared memory (C/C++), linux pipe, sockets (TCP/UDP), etc. and few high-level - queue (JMS, Rabbit), RPC. Both daemons should run on the same host, but obviously better approach is to abstract from connection type. What are typical solutions/libraries in python? I'm looking for an elegant and lightweight solution. I don't need external server, just two processes talking with each other. What should I use in python to do that?

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  • How can one describe a rock-paper-scissors relationship between 3 items?

    - by Madara Uchiha
    Let's say I have the following structure: abstract class Hand {} class Rock extends Hand {} class Paper extends Hand {} class Scissors extends Hand {} The goal is to make a function (or a method) Hand::compareHands(Hand $hand1, Hand $hand2), which would return the winning hand in a rock-paper-scissors match. That would be very easy with a bunch of ifs, but the point is to have a more robust structure, that's relying on polymorphism rather than on procedural code. P.S. this is done in actual production code, if someone is asking. This isn't some sort of challenge or homework. (It's not really rock-paper-scissors, but you get the point).

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  • designing multi module J2EE application

    - by user728947
    Might be my question is abstract or out of context, but i am asking here since i have little idea how this happens. I am wondering how big application/ platform break down there application in to multiple module and how they able to manage modules dependencies. For example in some E-commerce application they tend to break down it in various modules like pricing,promotions,shipping.import/export and many more. when we develop those application we hardly think about the underlying modules and how they have been designed to provides functionalists. Most of those module are not web-applications but are standalone module and not deployed in the web-app as jar files. can any one help me to understand how they break up things or is there any standard way to do this.any help/resources to get insight will really be helpful

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  • Why is the base class being called?

    - by oneBelizean
    I'm new to c# so bare with me. But here's my situation. interface Icontainer{ string name(); } abstract class fuzzyContainer : Icontainer{ string name(){ return "Fuzzy Container"; } } class specialContainer: fuzzyContainer{ string name(){ return base.name() + " Special Container"; } } Icontainer cont = new SpecialContainer(); cont.name(); // I expected "Fuzzy Container Special Container" as the output. When I run my code as described above the output is simply "Fuzzy Container". What am i missing here? Is there a better way to get the desired results?

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  • Receive messages for derived types in MVVMLight

    - by Hrvoje
    Shouldn't this test pass: [TestMethod] public void derived_message_subscription() { bool handled = false; Messenger.Default.Register<GenericMessage<baseClass>>(this, true, (msg) => handled = true); Messenger.Default.Send(new GenericMessage<testClass>(new testClass())); Assert.IsTrue(handled); } public abstract class baseClass { } public class testClass : baseClass { } I have to receive all messages for classes that inherits from one base class. MVVMLight has bool property receiveDerivedMessagesToo in Register method, but it seems to me that it isn't working.

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  • Rails architecture questions

    - by justinbach
    I'm building a Rails site that, among other things, allows users to build their own recipe repository. Recipes are entered either manually or via a link to another site (think epicurious, cooks.com, etc). I'm writing scripts that will scrape a recipe from these sites given a link from a user, and so far (legal issues notwithstanding) that part isn't giving me any trouble. However, I'm not sure where to put the code that I'm writing for these scraper scripts. My first thought was to put it in the recipes model, but it seems a bit too involved to go there; would a library or a helper be more appropriate? Also, as I mentioned, I'm building several different scrapers for different food websites. It seems to me that the elegant way to do this would be to define an interface (or abstract base class) that determines a set of methods for constructing a recipe object given a link, but I'm not sure what the best approach would be here, either. How might I build out these OO relationships, and where should the code go?

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  • System.ServiceModel.Channels.MessageHeader Error

    - by user220511
    I'm trying to get the following to work on my machine but I get an error (Cannot create an instance of the abstract class or interface 'System.ServiceModel.Channels.MessageHeader') using System; using System.IO; using System.Reflection; namespace com.mycompanyname.business { /// /// Summary description for SessionCreateRQClient. /// class SessionCreateRQClient { /// /// The main entry point. /// [STAThread] static void Main(string[] args) { try { // Set user information, including security credentials and the IPCC. string username = "user"; string password = "password"; string ipcc = "IPCC"; string domain = "DEFAULT"; string temp = Environment.GetEnvironmentVariable("tmp"); // Get temp directory string PropsFileName = temp + "/session.properties"; // Define dir and file name DateTime dt = DateTime.UtcNow; string tstamp = dt.ToString("s") + "Z"; //Create the message header and provide the conversation ID. MessageHeader msgHeader = new MessageHeader(); msgHeader.ConversationId = "TestSession"; // Set the ConversationId From from = new From(); PartyId fromPartyId = new PartyId(); PartyId[] fromPartyIdArr = new PartyId[1]; fromPartyId.Value = "WebServiceClient"; fromPartyIdArr[0] = fromPartyId; from.PartyId = fromPartyIdArr; msgHeader.From = from; To to = new To(); PartyId toPartyId = new PartyId(); PartyId[] toPartyIdArr = new PartyId[1]; toPartyId.Value = "WebServiceSupplier"; toPartyIdArr[0] = toPartyId; to.PartyId = toPartyIdArr; msgHeader.To = to; //Add the value for eb:CPAId, which is the IPCC. //Add the value for the action code of this Web service, SessionCreateRQ. msgHeader.CPAId = ipcc; msgHeader.Action = "SessionCreateRQ"; Service service = new Service(); service.Value = "SessionCreate"; msgHeader.Service = service; MessageData msgData = new MessageData(); msgData.MessageId = "mid:[email protected]"; msgData.Timestamp = tstamp; msgHeader.MessageData = msgData; Security security = new Security(); SecurityUsernameToken securityUserToken = new SecurityUsernameToken(); securityUserToken.Username = username; securityUserToken.Password = password; securityUserToken.Organization = ipcc; securityUserToken.Domain = domain; security.UsernameToken = securityUserToken; SessionCreateRQ req = new SessionCreateRQ(); SessionCreateRQPOS pos = new SessionCreateRQPOS(); SessionCreateRQPOSSource source = new SessionCreateRQPOSSource(); source.PseudoCityCode = ipcc; pos.Source = source; req.POS = pos; SessionCreateRQService serviceObj = new SessionCreateRQService(); serviceObj.MessageHeaderValue = msgHeader; serviceObj.SecurityValue = security; SessionCreateRS resp = serviceObj.SessionCreateRQ(req); // Send the request if (resp.Errors != null && resp.Errors.Error != null) { Console.WriteLine("Error : " + resp.Errors.Error.ErrorInfo.Message); } else { msgHeader = serviceObj.MessageHeaderValue; security = serviceObj.SecurityValue; Console.WriteLine("**********************************************"); Console.WriteLine("Response of SessionCreateRQ service"); Console.WriteLine("BinarySecurityToken returned : " + security.BinarySecurityToken); Console.WriteLine("**********************************************"); string ConvIdLine = "convid="+msgHeader.ConversationId; // ConversationId to a string string TokenLine = "securitytoken="+security.BinarySecurityToken; // BinarySecurityToken to a string string ipccLine = "ipcc="+ipcc; // IPCC to a string File.Delete(PropsFileName); // Clean up TextWriter tw = new StreamWriter(PropsFileName); // Create & open the file tw.WriteLine(DateTime.Now); // Write the date for reference tw.WriteLine(TokenLine); // Write the BinarySecurityToken tw.WriteLine(ConvIdLine); // Write the ConversationId tw.WriteLine(ipccLine); // Write the IPCC tw.Close(); //Console.Read(); } } catch(Exception e) { Console.WriteLine("Exception Message : " + e.Message ); Console.WriteLine("Exception Stack Trace : " + e.StackTrace); Console.Read(); } } } } I have added the reference System.ServiceModel and the lines: using System.ServiceModel; using System.ServiceModel.Channels; but I continue to get that error when trying to compile -- "Cannot create an instance of the abstract class or interface 'System.ServiceModel.Channels.MessageHeader'" I am using Microsoft Visual Studio 2008 Version 9.0.21022.8 RTM Microsoft .NET Framework Version 3.5 SP1 Professional Edition Is there another reference I have to add? Or a dll to move over? I wonder was the code above written for Framework 2.0 only? Thanks for your help.

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  • How Does a Login system generally work with OOP?

    - by fakingfantastic
    Sorry if this is a badly formed question, but I'm trying to make my web applications (using PHP) more OO. *EDIT* I'm developing the Framework myself */EDIT* Everything is great so far, I've made a Front Controller system that taps into a MVC system. The FC figures out what page you want, loads the specific page Controller (*EDIT* which extends an abstract Controller Object */EDIT*), which gets anything it needs from Models, and then calls the appropriate View. Very basic. But now, I need to make an admin section (quasi-CMS). How does a login system fit into the grand scheme of things? Do you set controllers as needing a login? If so, how? What If you only want certain views of a controller requiring login? Thanks in advance.

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  • 'Static/Constant' business ojects

    - by UpTheCreek
    I don't quite know how to ask this question, so I'll phase it as an example: Imagine in an application you have a Country object. There are two properties of this object: Name, and a 'Bordering Countries' collection. More properties might be added later, but it will be the kind of information that would change very rarely (e.g. changes of country names/borders) Lets say this application needs to know about all of the countries in the world. Where would you store these object's state? How would you new them up? It seems silly to store all this state in the DB, since it won't change very often. One option might be to have an abstract 'country' base object, and have a class for each country inheriting from this with the details of each country. But this doesn't seem quite right to me. What is the proper way of dealing with these kinds of objects?

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  • NHibernate: discriminator without common base class?

    - by joniba
    Is it possible to map two classes to the same property without them sharing a common base class? For example, a situation like this: class Rule { public virtual int SequenceNumber { get; set; } public virtual ICondition Condition { get; set; } } interface ICondition { } class ExpressionCondition : ICondition { public virtual string Expression { get; set; } } class ThresholdCondition : ICondition { public virtual int Threshold { get; set; } } I also cannot add some empty abstract class that both conditions inherit from because the two ICondition implementations exist in different domains that are not allowed to reference each other. (Please no responses telling me that this situation should not occur in the first place - I'm aware of it and it doesn't help me.)

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  • Questions about my program and Polymorphism

    - by Strobe_
    Ok, so basically I'm creating a program which allows the user to select a shape (triangle, square, circle) and then it takes in a int and calculates the boundary length and area. I have no problem doing this and have a program that's working perfectly. (https://gist.github.com/anonymous/c63a03c129560a7b7434 4 classes) But now I have to implement this with polymorphism concepts and I'm honestly struggling as to how to do it. I have a basic idea of what I want to do when it comes to inheritance Main | Shapes / | \ triangle circle square But I don't understand how I'm supposed to override when all the methods within the triangle/square/circle classes are unique, there are no "abstract" methods as such that I could inherit from the "Shapes" class. If somebody could make look quickly at the code I linked and suggest a way to do this it would be much appreciated. Sorry if I was bad at explaining this. Thanks.

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  • JVM specification and Java compiler code useful for SCJP preparation ?

    - by BenoitParis
    I'm preparing the SCJP exam with the almost official study book ("SCJP Sun Certified Programmer for Java 6 Exam 310-065") I understand that Java programming is writting code that fulfills a certain high-level contract; So that Java can stay platform-independent. However, I have trouble understanding and remembering things when it comes to highly specific SCJP items (and they are numerous) The book stays high-level and does not provide examples of how one compiler would handle things. This is the same thing for runtime issues (JVM level): things are too much abstract for me. Rules often seems arbitrary and therefore, with no well defined purpose, are difficult to remember. Or maybe it's that sometimes I just don't get the underlying purpose. And here is the question: Would a JVM specification and/or some java compiler code help in preparing the SCJP? Have you had the need for such material or is the book sufficient enough? Also, please share the resources you used, apart from the book.

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  • Returning a static array without using a class field

    - by Bart Friederichs
    I have the following base and derived (partial, for sake of brevity) classes: class Base { public abstract int[] someArray { get; } } class Derived : Base { private readonly static int[] _someArray = new int[] { 1,2,3,4 }; public override int[] someArray { get { return _someArray; } } } What I would like now, is put the new int[] { 1,2,3,4 } in the return part of the getter. But, that would create a new array every time the getter is called. Is it possible to directly return some kind of object, which stays the same for all objects of class Derived ? Something along the lines of (I know this is invalid C#): get { return (int[]) { 1, 2, 3, 4 }; }

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  • Creating a computer with pencil and paper [closed]

    - by Justian Meyer
    This concept has been brought to my attention before, but many people might know it from this popular comic here, where he uses stones instead of points on a paper. This concept is so abstract to me. A full-functioning computer that can manage algorithms, input, output, etc. without electricity? Surely, it's difficult to visualize because my definition of a computer is not exactly what the word sounds like COMPUTE-ER. Can someone help me bring the concept to light - the understanding, how to make one, etc? It seems like it'd be an interesting read, although I think I wouldn't be able to make it do anything. Many thanks in advance for responses. I've tried searching Google, but all I got were ways to diagram code and chart ideas. -.Justian.

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